Sony Patent | Information processing apparatus, information processing method, and acoustic system

Patent: Information processing apparatus, information processing method, and acoustic system

Drawings: Click to check drawins

Publication Number: 20210345057

Publication Date: 20211104

Applicant: Sony

Abstract

Provided is an information processing apparatus that carries out a process of deriving a head related transfer function. The information processing apparatus includes a detection unit that detects a position of a head of a user, a storage unit that stores a head related transfer function of the user, a determination unit that determines a position of a sound source for measuring the head related transfer function of the user based on the position of the head detected by the detection unit and information stored in the storage unit, a control unit that controls the sound source to output measurement signal sound from the position determined by the determination unit, and a calculation unit that calculates the head related transfer function of the user based on collected sound data obtained by collecting, at the position of the head, the measurement signal sound output from the sound source.

Claims

1. An information processing apparatus comprising: a detection unit that detects a position of a head of a user; a storage unit that stores a head related transfer function of the user; a determination unit that determines a position of a sound source for measuring the head related transfer function of the user based on the position of the head detected by the detection unit and information stored in the storage unit; and a control unit that controls the sound source to output measurement signal sound from the position determined by the determination unit.

2. The information processing apparatus according to claim 1, further comprising: a specification unit that specifies the user.

3. The information processing apparatus according to claim 1, wherein the determination unit determines a position of a sound source for measuring the head related transfer function of the user next without overlapping the position where the head related transfer function is already measured.

4. The information processing apparatus according to claim 1, wherein the control unit selects one of a plurality of sound sources arranged at different positions based on the position determined by the determination unit and causes the sound source to output measurement signal sound.

5. The information processing apparatus according to claim 1, wherein the control unit causes the sound source moved based on the position determined by the determination unit to output measurement signal sound.

6. The information processing apparatus according to claim 1, further comprising: a calculation unit that calculates the head related transfer function of the user based on collected sound data obtained by collecting, at the position of the head, the measurement signal sound output from the sound source.

7. The information processing apparatus according to claim 6, further comprising: a first determination unit that determines whether or not there is an abnormality in the collected sound data.

8. The information processing apparatus according to claim 7, wherein the first determination unit performs the determination by handling, as no-signal, the collected sound data in a time domain in which a measurement signal is not measured due to a metric space delay between the position of the head and the position of the sound source.

9. The information processing apparatus according to claim 6, further comprising: a second determination unit that determines whether or not there is an abnormality in the head related transfer function calculated by the calculation unit.

10. The information processing apparatus according to claim 6, wherein the calculation unit uses collected sound data of measurement signal sound output from the sound source near the position determined by the determination unit to interpolate the head related transfer function at the position determined by the determination unit.

11. The information processing apparatus according to claim 1, wherein the determination unit sequentially determines the position of the sound source for measuring the head related transfer function of the user next so as to evenly measure the head related transfer function throughout an area to be measured.

12. The information processing apparatus according to claim 1, wherein the determination unit sequentially determines the position of the sound source for measuring the head related transfer function of the user next based on a priority set in the area to be measured.

13. The information processing apparatus according to any one of claim 1, further comprising: an information presentation unit that presents information prompting the user to make an action of changing the position of the head when there is no sound source that generates the measurement signal sound at the position of the sound source determined by the determination unit.

14. The information processing apparatus according to claim 13, further comprising: a display, wherein the information presentation unit presents the information to be viewed by the user at a predetermined position of the display, and causes the sound source that is at a position determined by the determination unit for the head after the change in the position, to generate measurement signal sound when the user faces the information.

15. The information processing apparatus according to claim 13, comprising: a plurality of sound sources, wherein the control unit controls a sound source that is arranged at a position determined by the determination unit for the head after the change in the position, to output measurement signal sound.

16. The information processing apparatus according to claim 13, comprising: a plurality of sound sources, wherein the control unit determines a first sound source among the plurality of sound sources that outputs measurement signal sound, the information presentation unit determines a second sound source among the plurality of sound sources that presents acoustic information prompting the user to make an action, and when the user faces the acoustic information, the first sound source is in a positional relation corresponding to the position determined by the determination unit with respect to the position of the head.

17. The information processing apparatus according to claim 1, wherein the measurement signal sound includes a time-stretch pulse in which power is inversely proportional to frequency.

18. The information processing apparatus according to claim 1, wherein the measurement signal sound includes a time-stretch pulse in which amplitude at each frequency is adjusted according to a frequency spectrum of stationary noise of a measurement environment.

19. An information processing method comprising: a detection step of detecting a position of a head of a user; a determination step of determining a position of a sound source for measuring a head related transfer function of the user based on the position of the head detected in the detection step and information stored in a storage unit that stores the head related transfer function of the user; and a control step of controlling the sound source to output measurement signal sound from the position determined in the determination step.

20. An acoustic system comprising: a control apparatus including a detection unit that detects a position of a head of a user, a storage unit that stores a head related transfer function of the user, a determination unit that determines a position of a sound source for measuring the head related transfer function of the user based on the position of the head detected by the detection unit and information stored in the storage unit, a control unit that controls the sound source to output measurement signal sound from the position determined by the determination unit, and a calculation unit that calculates the head related transfer function of the user based on collected sound data obtained by collecting, at the position of the head, the measurement signal sound output from the sound source; and a terminal apparatus including a sound collection unit that is mounted on the user and used and that collects, at the position of the head, the measurement signal sound output from the sound source, and a transmission unit that transmits data collected by the sound collection unit to the control apparatus.

Description

TECHNICAL FIELD

[0001] A technique disclosed in the present specification mainly relates to an information processing apparatus, an information processing method, and an acoustic system that process acoustic information.

BACKGROUND ART

[0002] In an acoustic field, there is a known technique for using a head related transfer function (HRTF) of a user to increase reproducibility of stereophonic sound. The HRTF largely depends on the shapes of the head and the auricles of the user, and it is desirable that the user be the subject in measuring the head related transfer function.

[0003] However, in a conventional measurement method of the head related transfer function, special equipment provided with a large number of speakers is necessary, and opportunities for the measurement of the user are limited. It is difficult to use the head related transfer functions directly measured from the user to reproduce the stereophonic sound. Therefore, a method is often used, in which a dummy head microphone simulating the head including the ears is used to measure and set head related transfer functions of an average user, and the stereophonic sound for individual users is reproduced.

[0004] For example, a head related transfer function selection apparatus is proposed that selects the head related transfer function suitable for the user from a database including a plurality of head related transfer functions (see PTL 1). However, the head related transfer function selection apparatus uses the head related transfer function considered to be close to the user among the head related transfer functions with average characteristics registered in the database. Therefore, compared to the case of using the head related transfer function obtained by directly measuring the user, it cannot be denied that the sense of realism is reduced in reproducing the stereophonic sound.

[0005] In addition, an apparatus is proposed that measures head related transfer functions simulating propagation characteristics of sound propagating from each direction to the ears (see PTL 2). However, the apparatus uses a large speaker traverse (movement apparatus) to measure head related transfer functions at equal intervals, and large-scale equipment is necessary. Therefore, it is considered that the measurement burden of the user as a subject is large.

[0006] On the other hand, a control apparatus is proposed that acquires a positional relation between the head or the ear of the user and the sound source from an image captured by a smartphone held by the user and that causes the smartphone to generate sound to simply measure the head related transfer function (see PTL 3). However, there is a demand for a head related transfer function measurement technique that increases the measurement accuracy without imposing a measurement burden on the user as much as possible.

CITATION LIST

Patent Literature

[0007] [PTL 1]

[0008] Japanese Patent Laid-Open No. 2014-99797 [0009] [PTL 2]

[0010] Japanese Patent Laid-Open No. 2007-251248 [0011] [PTL 3]

[0012] Japanese Patent Laid-Open No. 2017-16062

SUMMARY

Technical Problem

[0013] An object of the technique disclosed in the present specification is to provide an information processing apparatus, an information processing method, and an acoustic system that carry out a process for deriving a head related transfer function.

Solution to Problem

[0014] The technique disclosed in the present specification has been made in view of the problem, and a first aspect of the technique provides an information processing apparatus including a detection unit that detects a position of a head of a user, a storage unit that stores a head related transfer function of the user, a determination unit that determines a position of a sound source for measuring the head related transfer function of the user based on the position of the head detected by the detection unit and information stored in the storage unit, and a control unit that controls the sound source to output measurement signal sound from the position determined by the determination unit. In addition, the information processing apparatus further includes a calculation unit that calculates the head related transfer function of the user based on collected sound data obtained by collecting, at the position of the head, the measurement signal sound output from the sound source.

[0015] The determination unit determines a position of a sound source for measuring the head related transfer function of the user next without overlapping the position where the head related transfer function is already measured, thereby allowing to efficiently measure the head related transfer function.

[0016] In addition, a second aspect of the technique disclosed in the present specification provides an information processing method including a detection step of detecting a position of a head of a user, a determination step of determining a position of a sound source for measuring a head related transfer function of the user based on the position of the head detected in the detection step and information stored in a storage unit that stores the head related transfer function of the user, and a control step of controlling the sound source to output measurement signal sound from the position determined in the determination step.

[0017] In addition, a third aspect of the technique disclosed in the present specification provides an acoustic system including a control apparatus and a terminal apparatus. The control apparatus includes a detection unit that detects a position of a head of a user, a storage unit that stores a head related transfer function of the user, a determination unit that determines a position of a sound source for measuring the head related transfer function of the user based on the position of the head detected by the detection unit and information stored in the storage unit, a control unit that controls the sound source to output measurement signal sound from the position determined by the determination unit, and a calculation unit that calculates the head related transfer function of the user based on collected sound data obtained by collecting, at the position of the head, the measurement signal sound output from the sound source. The terminal apparatus includes a sound collection unit that is mounted on the user and used and that collects, at the position of the head, the measurement signal sound output from the sound source, and a transmission unit that transmits data collected by the sound collection unit to the control apparatus.

[0018] The “system” mentioned here denotes a logical set of a plurality of apparatuses (or functional modules that realize specific functions), and whether or not the apparatuses or the functional modules are in a single housing does not particularly matter.

Advantageous Effect of Invention

[0019] The technique disclosed in the present specification can provide the information processing apparatus, the information processing method, and the acoustic system that carry out the process for deriving the head related transfer function.

[0020] Note that the advantageous effects described in the present specification are illustrative only, and the advantageous effects of the present invention are not limited to these. In addition, the present invention may also attain additional advantageous effects other than the advantageous effects described above.

[0021] Other objects, features, and advantages of the technique disclosed in the present specification will become apparent from more detailed description based on the embodiment described later and the attached drawings.

BRIEF DESCRIPTION OF DRAWINGS

[0022] FIG. 1 is a diagram illustrating an external configuration example of an HRTF measurement system 100.

[0023] FIG. 2 is a diagram schematically illustrating a function boat configuration example of the HRFT measurement system 100.

[0024] FIG. 3 is a diagram illustrating a basic process sequence example executed between a control box 2 and a terminal apparatus 1 in measuring an HRTF.

[0025] FIG. 4 is a diagram illustrating an example of a sound source position of a head horizontal plane of HRTF data.

[0026] FIG. 5 is a diagram illustrating an example of the sound source position of the head horizontal plane of the HRTF data.

[0027] FIG. 6 is a diagram illustrating an example of arranging 49 measurement points on a spherical surface at a radius of 75 cm from a head of a user.

[0028] FIG. 7 is a diagram illustrating a state in which the user goes through gates 5, 6, 7, 8, … on foot (state of measuring the HRTFs all around the user).

[0029] FIG. 8 is a diagram illustrating the state in which the user goes through the gates 5, 6, 7, 8, … on foot (state of measuring the HRTFs all around the user).

[0030] FIG. 9 is a diagram illustrating an example of providing the HRTF measurement system 100 in a living room.

[0031] FIG. 10 is a diagram illustrating a configuration example of an HRTF measurement system 1000.

[0032] FIG. 11 is a diagram illustrating a state in which a pet robot or a drone moves around the user (state of measuring the HRTFs all around the user).

[0033] FIG. 12 is a diagram illustrating an external configuration example of the terminal apparatus 1.

[0034] FIG. 13 is a diagram illustrating a state in which the terminal apparatus 1 illustrated in FIG. 12 is mounted on the left ear of a person (dummy head).

[0035] FIG. 14 is a diagram illustrating an example of data collected by a sound collection unit 109.

[0036] FIG. 15 is a diagram illustrating an example of a data structure of a table storing information of each measurement point.

[0037] FIG. 16A is a diagram for describing an HRTF measurement signal.

[0038] FIG. 16B is a diagram for describing an HRTF measurement signal.

[0039] FIG. 16C is a diagram for describing an HRTF measurement signal.

[0040] FIG. 16D is a diagram for describing an HRTF measurement signal.

[0041] FIG. 17 is a diagram illustrating a configuration example of an acoustic output system 1700 that uses position-based HRTFs.

[0042] FIG. 18 is a diagram illustrating a configuration example of an HRTF measurement system 1800.

[0043] FIG. 19 is a diagram illustrating an implementation example of the HRTF measurement system 1800.

[0044] FIG. 20 is a diagram illustrating general spherical coordinates.

[0045] FIG. 21 is a diagram illustrating a state in which an origin of the spherical coordinates is set on the head of a subject of the HRTF.

[0046] FIG. 22 is a diagram illustrating a state in which sound sources for HRTF measurement are installed at positions represented by the spherical coordinates.

[0047] FIG. 23 is a diagram illustrating an operation example of making the user change the posture in the HRTF measurement system 1800.

[0048] FIG. 24 is a diagram illustrating the operation example of making the user change the posture in the HRTF measurement system 1800.

DESCRIPTION OF EMBODIMENT

[0049] Hereinafter, an embodiment of the technique disclosed in the present specification will be described in detail with reference to the drawings.

[0050] First, “position,” “angle,” and “distance” in an HRTF measurement system disclosed in the present specification will be described. In the embodiment described below, a position of a measurement point for measuring an HRTF of a user will be expressed by general spherical coordinates. As illustrated in FIG. 20, the position in the spherical coordinates can be expressed by (.PHI., .theta., r). FIG. 21 illustrates a state in which an origin of the spherical coordinates is set on the head of a subject of the HRTF. In FIG. 21, .PHI. is defined as a horizontal direction angle (Azimuth), and .theta. is defined as an elevation direction angle (Elevation). As for .PHI., the front side of the head (FRONT) is zero degrees, and the back side (BACK) is 180 degrees. Therefore, the side surface of the left ear is 90 degrees, and the side surface of the right ear is 270 degrees. As for .theta., the top of the head (TOP) is 90 degrees, and a plane connecting the front side and the back side of the head (reference plane) is zero degrees. By the way, a downward direction from the reference plane is a negative angle. In addition, r is defined as a distance between the head of the subject and a sound source to be localized. FIG. 22 illustrates a state in which sound sources for HRTF measurement are installed at positions represented by the spherical coordinates.

[0051] In the measurement using the speaker traverse (movement apparatus) disclosed in PTL 2, the distance r from the measurement sound source to the head is fixed, and .PHI. and .theta. are changed for the measurement. When the distance r is fixed, the measurement is performed for a plurality of positions (.PHI., .theta., r), and the HRTF at an optional position (.PHI.’, .theta.’, r) that is not a measurement point can be calculated by interpolation using a technique such as spline interpolation.

[0052] The present embodiment allows measurement at a position different from the position where the position (.PHI., .theta., r) is set as a measurement point. Such a system is useful in a case of measuring the HRTF in a situation in which the position is not fixed, such as when the subject moves or changes the posture in the HRTF measurement system. In a case where the position of the measurement of the head of the user is (.PHI.’, .theta.’, r’), and the position of the set measurement point is (.PHI., .theta., r), an approximate value of the HRTF is measured. In this case, interpolation calculation using a generally well-known technique can be performed to obtain the HRTF at the position (.PHI., .theta., r) of the measurement point from the HRTF of the measurement point approximated by the position (.PHI.’, .theta.’, r’) and from the values of a plurality of measurement points measured at more accurate positions in the surroundings. In addition, an absolute value of a position error d=( .PHI., .theta., r)-(.PHI.’, .theta.’, r’) allowed for the position that can be approximated may be set within a certain range (|d|<=D), and the HRTF measurement system may be set to allow the approximate measurement within the range. In such a way, the measurement in the allowed range can be performed.

[0053] Note that the “position” in the present specification has three meanings including “position” of the measurement point described above, “position” where the user as a subject exists, and “position” of a sound source or the like for measurement or for drawing attention of the subject. It should be noted that the meaning of “position” is properly used as necessary in the HRTF measurement system described below.

[0054] FIG. 1 illustrates an external configuration example of an HRTF measurement system 100 in which the technique disclosed in the present specification is applied. In addition, FIG. 2 schematically illustrates a functional configuration example of the HRFT measurement system 100.

[0055] With reference to FIG. 1, a terminal apparatus 1 including a sound collection unit 109 is mounted on the head of the user. The structure of the terminal apparatus 1 will be described later. A structure for attaching an open-ear sound collection unit 109 to the ear of the user is provided as illustrated in FIG. 13, and the physical and mental burden of the user wearing the terminal apparatus 1 on the head is significantly small. A control box 2 and a user specification apparatus 3 are provided near the user. However, the control box 2 and the user specification apparatus 3 may not be individual housings, and constituent components of the control box 2 and the user specification apparatus 3 may be housed in a single housing. Furthermore, functional blocks inside of the control box 2 and the user specification apparatus 3 may be arranged in separate housings.

[0056] In addition, a plurality of gates 5, 6, 7, 8, … , each including an arch-shaped frame, is installed in a traveling direction of the user indicated by reference number 4. A plurality of speakers included in an acoustic signal generation unit 106 (described later) is installed at different places on the gate 5 in the front. In addition, a user position posture detection unit 103 (described later) is installed on the second gate 6 from the front. The acoustic signal generation unit 106 and the user position posture detection unit 103 may be alternately installed on the third and following gates 7, 8, … .

[0057] The user may not go straight in the traveling direction 4 in a constant posture. The user may meander or may be crouched, and the relative position and the posture with respect to the acoustic signal generation unit 106 may vary.

[0058] With reference to FIG. 2, the HRTF measurement system 100 includes a storage unit 101, a user specification unit 102, the user position posture detection unit 103, a sound source position determination unit 104, a sound source position changing unit 105, the acoustic signal generation unit 106, a calculation unit 107, and a communication unit 108. In addition, the HRTF measurement system 100 includes the sound collection unit 109, a communication unit 110, and a storage unit 111 on the side of the user as a measurement target of the HRTF.

[0059] The storage unit 101, the user position posture detection unit 103, the sound source position determination unit 104, the sound source position changing unit 105, the acoustic signal generation unit 106, the calculation unit 107, and the communication unit 108 are housed in the control box 2. In addition, the user specification unit 102 is housed in the user specification apparatus 3, and the user specification apparatus 3 is externally connected to the control box 2. In addition, the sound collection unit 109, the communication unit 110, and the storage unit 111 are housed in the terminal apparatus 1 mounted on the head of the user as a measurement target of the HRTF. Furthermore, the communication unit 108 on the control box 2 side and the communication unit 110 on the terminal apparatus 1 side are connected to each other through, for example, wireless communication.

[0060] In a case where the terminal apparatus 1 and the control box 2 communicate through a radio wave, each of the communication unit 108 and the communication unit 110 is equipped with an antenna (not illustrated). However, optical communication, such as infrared rays, can be used between the terminal apparatus 1 and the control box 2 in an environment with a little influence of interference. In addition, although the terminal apparatus 1 is basically battery-driven, the terminal apparatus 1 may be driven by a commercial power supply.

[0061] The user specification unit 102 includes a device that uniquely determines the current measurement target of HRTF. The user specification unit 102 includes, for example, an apparatus that can read (or identify) an ID card with IC, a magnetic card, a piece of paper on which a one-dimensional or two-dimensional barcode is printed, a smartphone in which an application for specifying the user is executed, a watch-type device including a wireless tag, a bracelet-type device, and the like. In addition, the user specification unit 102 may be a device that specifies the user by reasoning biometric information, such as fingerprint impression and vein authentication. In addition, the user specification unit 102 may specify the user based on a recognition result of a two-dimensional image or three-dimensional data of the user acquired by a camera or a 3D scanner. The user is managed by a user identifier (ID) registered in advance. In this case, the user as a temporary user may perform the first measurement of the HRFT, and a specific user ID and the measured HRTF may be associated after the measurement.

[0062] A process for measuring the HRTF of each user specified by the user specification unit 102 is executed in the control box 2.

[0063] HRTF measurement data of each user specified by the user specification unit 102, data necessary for the HRTF measurement process, and the like are stored in the storage unit 101. A mapping table or the like of users and data management storage areas of the users can be prepared to manage the data. Note that in the following description, one piece of data will be described for each user. Ideally, it is desirable to collect the HRTF data of each of the left ear and the right ear for each user. To do so, the HRTF data of each user is sorted into data for left ear and data for right ear and managed in the storage unit 101.

[0064] For each user, the HRTFs need to be measured at a plurality of measurement points in the spherical coordinates. In other words, the measurement points of HRTFs exist all around the user, and a set of HRTFs measured at all the measurement points is the HRTF data of the user. In the HRTF measurement system 100 according to the present embodiment, the user position posture detection unit 103 uses a camera, a distance sensor, or the like to measure the position and the posture of the head of the user (direction of head (may be direction of face or part of face (such as nose, eyes, and mouth), which similarly applies hereinafter)), and the sound source position determination unit 104 uses the measurement result to determine whether or not there is a sound source at a position where the HRTF needs to be measured for the user next (that is, whether or not the measurement is possible at the position that requires the measurement of the HRTF). To efficiently measure the HRTF data of the user at a plurality of measurement points in a short time, the sound source position determination unit 104 needs to extract the position of the sound source for measuring the HRTF next from position information of unmeasured measurement points to sequentially determine the sound source at the position for measuring the HRTF at the extracted measurement point so that the HRTF at an already measured position is not repeatedly measured. However, the measurement points for which quality determination of measurement data described later or quality determination of calculated HRTF has failed may be recorded as “unmeasured” or “remeasurement,” and the measurement of the HRTF may be repeated later for the measurement points.

[0065] More specifically, there is also reflected sound and reverberation unique to each acoustic environment, and it is preferable to acquire the HRTF data of each user for each acoustic environment. In the present embodiment, it is assumed that the HRTF data of each user is managed in association with the acoustic environment information in the storage unit 101. In addition, the terminal apparatus 1 or the control box 2 may be equipped with a sensor for sensing the acoustic environment during the HRTF measurement, or the user may instruct and input the acoustic environment at the time of the measurement of the HRTF through a UI (User Interface). As an example of acquiring and managing the HRTF data of each user for each acoustic environment, it is sufficient if the HRTF data is stored and managed for each combination of the environment information identifier of the acoustic environment information and the user identifier (ID) of the user information in FIG. 2.

[0066] The user position posture detection unit 103 measures at which coordinates in the HRTF measurement system 100 the position of the head of the user specified by the user specification unit 102 exists and in which direction the user is facing (that is, posture information of user) in the spherical coordinates around the coordinates in a case where the head of the user is placed at the coordinate position. The user position posture detection unit 103 includes, for example, one or more cameras, one of a TOF (Time Of Flight) sensor, a laser measurement device (such as LiDAR), an ultrasonic sensor, or the like, or a combination of a plurality of sensors. Therefore, the HRTF measurement system 100 can measure the distance r from each speaker included in the acoustic signal generation unit 106 to the head of the user. In the example illustrated in FIG. 1, a stereophonic sensor for user position posture detection is provided on the second gate 6 from the front in the traveling direction 4 of the user (described above). Note that although not illustrated, the user position posture detection unit 103 can also use a skeleton model analysis unit using an image recognition technique to recognize the direction of the head or use an inference unit using an artificial intelligence technique (technique such as deep neural network) to predict the action of the user to thereby provide, as part of the posture information, information indicating whether or not the position of the head is stable in a certain time period. In such a way, the measurement of the HRTF can be more stable.

[0067] The acoustic signal generation unit 106 includes one or more speakers and provides sound sources that generate signal sound for HRTF measurement. In addition, the sound sources can also be used as sound sources that generate signal sound as information viewed by the user (or information prompting the user to view) as described later. In the example illustrated in FIG. 1, a plurality of speakers included in the acoustic signal generation unit 106 is installed at different places on the gate 5 in the front in the traveling direction 4 of the user (described above).

[0068] The sound source position determination unit 104 selects a position (.PHI., .theta., r) of the HRTF to be measured next for the user as the current measurement target of HRTF (or the user currently specified by the user specification unit 102) from the relative position of the position and posture information of the head of the user obtained by the user position posture detection unit 103 and the acoustic signal generation unit 106 and sequentially determines the sound source (speaker) at the position for measuring the TRTF of the selected position. It is preferable in terms of the efficiency of processing that each sound source hold an identifier (ID), and the sound source be controlled based on the ID after the sound source is determined based on the position. Furthermore, in the case where the stability information of the posture is provided as posture information as described above, the sound source position may be determined when the posture is stable. In such a way, the measurement of the HRTF can be more stable.

[0069] The sound source position changing unit 105 controls the acoustic signal generation unit 106 to generate signal sound for HRTF measurement from the position of the sound source determined by the sound source position determination unit 104. In the present embodiment, the acoustic signal generation unit 106 includes a plurality of speakers arranged at different positions as illustrated in FIG. 1. The sound source position changing unit 105 designates the ID of the sound source and controls the output switch of each speaker to generate the signal sound for HRTF measurement from the speaker as a sound source at the position determined by the sound source position determination unit 104. Alternatively, in a case where there is no speaker as a sound source at the strict position corresponding to the position (.PHI., .theta., r) determined by the sound source position determination unit 104, signal sound for HRTF measurement may be generated from a speaker at (.PHI.’, .theta.’, r’) near the position. Furthermore, the calculation unit 107 in a later stage may interpolate the HRTF at a desirable position based on data obtained by collecting signal sound output from two or more positions near the desirable position. Furthermore, in a case where there is a measurement point not finished with the measurement of the HRTF due to stationary environmental noise of the surroundings or sudden noise, the interpolation may also be performed based on HRTF data at a surrounding measurement point normally finished with the measurement. In the case where there is no speaker as a sound source at the strict position, the fact that the measurement is approximate measurement and the approximated position can be recorded in an HRTF measurement data table stored for each user, and the table can be used for the interpolation calculation. In addition, “approximate measurement” can be recorded in the HRTF data measured at the approximated position, and the HRTF can be remeasured later. Furthermore, in the case of the approximate measurement, information, such as measured approximate position and measurement accuracy, can be recorded together, and the HRTF measurement system 100 can later use the information in determining the necessity of remeasurement.

[0070] The sound collection unit 109 includes a microphone that converts a sound wave into an electrical signal. The sound collection unit 109 is housed in the terminal apparatus 1 mounted on the head of the user as a measurement target of the HRTF and collects signal sound for HRTF measurement emitted from the acoustic signal generation unit 106. Note that quality determination may be performed to determine whether or not there is an abnormality in the acoustic signal collected by the sound collection unit 109. Furthermore, the data measured by the sound collection unit 109 is temporarily stored in the storage unit 111 and transmitted from the terminal apparatus 1 to the control box 2 side through the communication unit 110.

[0071] The data measured by the sound collection unit 109 is time axis waveform information obtained by collecting the HRTF measurement signal emitted from the sound source at the position determined by the sound source position determination unit 104. On the control box 2 side, once the data measured by the sound collection unit 109 is received through the communication unit 108, the data is stored in the storage unit 101. Furthermore, the calculation unit 107 calculates the HRTF at the position of the sound source from the time axis waveform information measured for each position of the sound source and causes the storage unit 101 to store the HRTF. When the calculation unit 107 calculates the HRTF, quality determination is performed to determine whether or not the data measured by the sound collection unit 109 is correctly measured (or the quality determination may be performed in causing the storage unit 101 to store the HRTF). In addition, quality determination of the HRTF calculated by the calculation unit 107 is also performed. Note that the calculation unit 107 may calculate the HRTF in parallel with the sound collection of the HRTF measurement signal or may calculate the HRTF when some amount of unprocessed collected sound data is accumulated in the storage unit 101 or at optional timing. Although not illustrated, in a case where the terminal apparatus 1 further includes a position detection sensor such as a GPS (Global Positioning System), communication between the communication unit 110 of the terminal apparatus 1 and the communication unit 108 of the control box 2 can be used to transmit the information of the position detection sensor to the control box 2 to allow the control box 2 to use the information to measure the distance to the position of the head of the user. In such a way, there is an advantageous effect that the information of distance to the head of the user can be obtained even in a case where there is no distance measurement apparatus fixed to the HRTF measurement system 100.

[0072] Note that the process and the data management in at least part of the functional modules in the control box 2 illustrated in FIG. 2 may be carried out on a cloud. Here, the “cloud” in the present specification generally denotes cloud computing. The cloud provides a computing service through a network such as the Internet. In a case where computing is performed at a position closer to the information processing apparatus that receives the service in the network, the computing is also called edge computing, fog computing, or the like. There is also a case in which the cloud in the present specification is understood to denote a network environment or a network system for cloud computing (resources for computing (including processor, memory, wireless or wired network connection equipment, and the like)). Furthermore, there is also a case in which the cloud is understood to denote a service or a provider provided in a form of a cloud.

[0073] FIG. 3 illustrates a basic process sequence example executed between the control box 2 and the terminal apparatus 1 when the HRTF measurement system 100 according to the present embodiment measures the HRTF.

[0074] The control box 2 side waits until the user specification unit 102 of the user specification apparatus 3 specifies the user (No in SEQ301). Here, it is assumed that the user is wearing the terminal apparatus 1 on the head.

[0075] Furthermore, once the user specification unit 102 specifies the user (Yes in SEQ301), the control box 2 transmits a connection request to the terminal apparatus 1 (SEQ302) and waits until a connection finish notification is received from the terminal apparatus 1 (No in SEQ303).

[0076] On other hand, the terminal apparatus 1 side waits until the connection request is received from the control box 2 (No in SEQ351). Furthermore, once the terminal apparatus 1 receives the connection request from the control box 2 (Yes in SEQ351), the terminal apparatus 1 executes a process of connecting to the control box 2 and then returns a connection finish notification to the control box 2 (SEQ352). Subsequently, the terminal apparatus 1 prepares the sound collection of the HRTF measurement signal to be executed by the sound collection unit 109 (SEQ353) and waits for a notification of output timing of the HRTF measurement signal from the control box 2 side (No in SEQ354).

[0077] Once the connection finish is received from the terminal apparatus 1 (Yes in SEQ303), the control box 2 notifies the terminal apparatus 1 of the output timing of the HRTF measurement signal (SEQ304). Furthermore, the control box 2 waits for a defined time (SEQ305) and outputs the HRTF measurement signal from the acoustic signal generation unit 106 (SEQ306). Specifically, the HRTF measurement signal is output from the sound source (speaker) corresponding to the sound source position changed by the sound source position changing unit 105 according to the determination by the sound source position determination unit 104. Subsequently, the control box 2 waits to receive the sound collection finish notification and the measurement data from the terminal apparatus 1 side (No in SEQ307).

[0078] In response to the notification of the output timing of the HRTF measurement signal from the control box 2 (Yes in SEQ354), the terminal apparatus 1 starts the sound collection process of the HRTF measurement signal (SEQ355). Furthermore, once the terminal apparatus 1 collects the HRTF measurement signal for a defined time (Yes in SEQ356), the terminal apparatus 1 transmits the sound collection finish notification and the measurement data to the control box 2 (SEQ357).

[0079] Once the control box 2 receives the sound collection finish notification and the measurement data from the terminal apparatus 1 side (Yes in SEQ307), the control box 2 checks whether or not the acquisition of the measurement data necessary and sufficient for calculating the HRTF of the user specified in SEQ351 is finished (SEQ308). Here, the control box 2 also performs the quality determination to determine whether or not there is an abnormality in the acoustic signal collected by the sound collection unit 109 on the terminal apparatus 1 side.

[0080] In a case where the acquisition of the measurement data necessary and sufficient for calculating the HRTF is not finished yet (No in SEQ308), the control box 2 transmits a measurement continuation notification to the terminal apparatus (SEQ309) and returns to SEQ304 to repeatedly carry out the notification of the output timing of the HRTF measurement signal and the transmission process of the HRTF measurement signal.

[0081] Furthermore, once the acquisition of the measurement data necessary and sufficient for calculating the HRTF is finished (Yes in SEQ308), the control box 2 transmits a measurement finish notification to the terminal apparatus 1 (SEQ310) and finishes the process for the HRTF measurement.

[0082] In a case where the measurement continuation notification is received from the control box 2 (No in SEQ358) after the transmission of the sound collection finish notification and the measurement data (SEQ357), the terminal apparatus 1 returns to SEQ354 to wait for the notification of the output timing of the HRTF measurement signal from the control box 2 side and repeatedly carries out the sound collection process of the HRTF measurement signal and the transmission of the sound collection finish notification and the measurement data to the control box 2.

[0083] Furthermore, in a case where the measurement finish notification is received from the control box 2 (Yes in SEQ358), the terminal apparatus 1 finishes the process for the HRTF measurement.

[0084] FIGS. 4 and 5 illustrate an example of the sound source position of a head horizontal plane (that is, .theta.=zero degrees in spherical coordinates) of the HRTF data to be measured. In the example illustrated in FIGS. 4 and 5, the measurement point is arranged every 30 degrees on a circumference with a radius of 150 cm in the spherical coordinates around the head of the user in the head horizontal plane of the user, and the measurement point is arranged every 15 degrees on a circumference with a radium of 250 cm around the head of the user. Furthermore, in FIGS. 4 and 5, dotted lines illustrate an example of the transfer function from the sound source position at the distance of 150 cm in the direction of an angle of 30 degrees to the right from the front of the user to the left and right ears of the user. In other words, the positions of the measurement points are defined by (0, .PHI.1+.DELTA..PHI.1, 250 cm), where .PHI.1=zero degrees and .DELTA..PHI.1=15 degrees, and (0, .PHI.2+.DELTA..PHI.2, 150 cm), where .PHI.2=zero degrees and .DELTA..PHI.2=30 degrees, in the spherical coordinates.

[0085] Basically, the sound source position can be set at the position of the measurement point of the HRTF, and the HRTF of the measurement point can be obtained based on the collected sound data of the HRTF measurement signal output from the sound source position. The required number and density (spatial distribution) of measurement points vary depending on the usage or the like of the HRTF. In addition, the number of sound source positions, that is, measurement points, varies according to the required accuracy of HRTF data. FIG. 6 illustrates an example of arranging 49 measurement points on a spherical surface at a radius of 75 cm from the head of the user.

[0086] The HRTFs of two or more measurement points cannot be measured at the same time exactly, and therefore, the HRTFs need to be sequentially measured for each measurement point. According to the configuration of the HRTF measurement system 100 illustrated in FIG. 1, in a period in which the user provided with the terminal apparatus 1 on the head goes through the gates 5, 6, 7, 8, … on foot, the sound source position determination unit 104 sequentially determines the position of the sound source for measuring the HRTF next without overlapping the sound source position at the position where the HRTF is already measured, and the sound source position changing unit 105 causes one of the plurality of speakers arranged on the gates 5, … to generate the signal sound for HRTF measurement to set the position of the sound source determined by the sound source position determination unit 104 as the next sound source position.

[0087] In the terminal apparatus 1, the sound collection unit 109 collects the sound of the HRTF measurement signal and transmits the collected sound data to the control box 2 through the communication unit 110. The calculation unit 107 calculates the HRTF at the corresponding measurement point based on the received collected sound data and causes the storage unit 101 to store the HRTF.

[0088] FIGS. 7 and 8 illustrate a state in which the user goes through the gates 5, 6, 7, 8, … on foot. While the user walks in the direction indicated by the arrow 4, the relative position between the head of the user and each of the plurality of speakers arranged on the gate 5 changes every moment. Therefore, even if there are measurement points of HRTF all around the user, it is expected that one of the plurality of speakers arranged on the gates 5, … matches the position of the measurement point of the HRTF at some time while the user walks in the direction indicated by the arrow 4.

[0089] For the current position and posture of the head of the user, the sound source position determination unit 104 determines, each time, the sound source position not overlapping the already measured measurement points. Furthermore, the sound source position changing unit 105 selects the speaker matching the sound source position sequentially determined according to the movement of the user and causes the speaker to output the HRTF measurement signal. In such a way, the sound collection at the measurement point and the measurement of the HRTF are carried out.

[0090] Therefore, the HRTF can be efficiently measured at the measurement points all around the user while the user goes through the gates 5, 6, 7, 8, … on foot. Note that in the case where the speaker is not arranged at the sound source position strictly matching the position of the measurement point, the HRTF at the desirable position may be interpolated based on the data obtained by collecting the signal sound output from two or more positions near the position of the measurement point. Furthermore, in the case where there is a measurement point not finished with the measurement of the HRTF due to stationary environmental noise of the surroundings or sudden noise, the interpolation may also be performed based on the HRTF data of the surrounding measurement point normally finished with the measurement.

[0091] It is preferable that the sound source position determination unit 104 uniformly select the measurement points from the entire circumference to, for example, completely measure the head related transfer functions all around the user. Alternatively, the priority of the HRTF measurement may be set in advance for each measurement point, and the sound source position determination unit 104 may determine the next measurement point with a higher priority among the measurement points not overlapping the already measured measurement points. Even in a case where, for example, the HRTFs of all of the measurement points cannot be acquired while the user passes through the gates 5, 6, 7, 8, … just once, the HRTFs of the measurement points with higher priorities can be acquired early with a small number of passes.

[0092] By the way, the resolution of the sound source position of a human is high in the direction of the median plane (median sagittal plane), followed by the downward direction. On the other hand, the resolution is relatively low in the left and right directions. The reason that the resolution is high in the median plane direction is also based on the fact that how the sound from the sound source in the median plane direction is heard varies between the left ear and the right ear due to the difference between the shapes of the left and right auricles of humans. Therefore, a high priority may be allocated to a measurement point close to the median plane direction.

[0093] The HRTF measurement system 100 with the functional configuration illustrated in FIG. 2 measures the HRTFs of a large number of measurement points of the user according to the process sequence as illustrated in FIG. 3. However, equipment including large-scale structures, such as the plurality of gates 5, 6, 7, 8, … as illustrated in FIG. 1, is not always necessary for the measurement.

[0094] For example, as illustrated in FIG. 9, a plurality of speakers as the acoustic signal generation unit 106 can be arranged at various locations in a living room of a general household (places indicated by gray polygons in FIG. 9 are positions where the speakers are arranged), and the HRTF measurement signals can be sequentially output from the speakers. In such a way, the HRTF measurement system 100 with the functional configuration illustrated in FIG. 2 can be used to measure the HRTF at each position of the user. Although three people, parents and a son of the parents, present in the living room illustrated in FIG. 9, the user specification unit 102 specifies one of the three people as the measurement target of the HRTF.

[0095] The user position posture detection unit 103 measures at which coordinates in the HRTF measurement system 100 the position of the head of the user specified by the user specification unit 102 exists and in which direction the user is facing (that is, posture information of user) in the spherical coordinates around the coordinates. The position measurement allows the HRTF measurement system 100 to measure the distance r from each speaker to the head of the user. The sound source position determination unit 104 determines the position (.PHI., .theta., r) of the sound source for measuring the HRTF next, from the relative position between the position and posture information of the head of the user obtained by the user position posture detection unit 103 and each speaker. In this case, the sound source position determination unit 104 may determine the next measurement point without overlapping the already measured measurement points and may determine the next measurement point with a higher priority. Furthermore, the sound source position changing unit 105 causes one of the speakers to output the HRTF measurement signal to generate the signal sound for HRTF measurement from the position of the sound source determined by the sound source position determination unit 104. The subsequent sound collection process of the HRTF measurement signal and the calculation process of the HRTF based on the collected sound data are carried out according to the process sequence illustrated in FIG. 3 as in the case of using the equipment illustrated in FIG. 1.

[0096] Although the user (one of the three people, the parents and the son) as a measurement target of the HRTF sits on the sofa in FIG. 9, the user may not remain stationary, and the user is expected to move around in the living room soon. The user position posture detection unit 103 measures, every moment, the position and the posture of the head of the user moving around in the living room. The sound source position determination unit 104 determines, each time, the sound source position not overlapping the already measured measurement points, for the current position and posture of the head of the user. Furthermore, the sound source position changing unit 105 selects the speaker matching (or approximate to) the sound source position sequentially determined according to the movement of the user and causes the speaker to output the HRTF measurement signal to carry out the sound collection at the measurement point and the measurement of the HRTF.

[0097] Therefore, in the example illustrated in FIG. 9, the sound collection of the HRTF measurement signal and the measurement of the HRTF are steadily carried out in the background at all of the measurement points while the user lives an everyday life in the living room, and the HRTF data of the user can be acquired. In a case where a plurality of users presents in the living room, the HRTF data can be acquired for each user. In addition, the HRTF measurements of the users can also be performed in parallel in time division. The equipment as illustrated in FIG. 1 is not necessary for the HRTF measurement, and the user does not have to perform a special operation for the HRTF measurement, such as passing under the gates 5, 6, 7, 8, … . In addition, a large-scale apparatus such as a speaker traverse (movement apparatus) (see PTL 2) is not necessary. There is no physical and mental burden for the user, and the measurement of the HRTF can be advanced without the user noticing the measurement.

[0098] FIG. 10 illustrates a configuration example of an HRTF measurement system 1000 according to a modification of the system configuration illustrated in FIG. 2. Here, the same constituent elements as in the HRTF measurement system 100 illustrated in FIG. 2 are provided with the same reference numbers, and the detailed description will not be repeated.

[0099] In the HRTF measurement system 100 illustrated in FIG. 2, the acoustic signal generation unit 106 includes a plurality of speakers arranged at different positions, and the sound source position changing unit 105 is configured to select one of the speakers at the position determined by the sound source position determination unit 104 and cause the speaker to output the HRTF measurement signal. On the other hand, in the HRTF measurement system 1000 illustrated in FIG. 10, a sound source position movement apparatus 1001 is configured to move the acoustic signal generation unit 106 including a speaker and the like to the measurement point to generate the signal sound for HRTF measurement from the position of the sound source determined by the sound source position determination unit 104.

[0100] The user position posture detection unit 103 measures, every moment, the position and the posture of the head of the user as a measurement target. The sound source position determination unit 104 determines, each time, the sound source position not overlapping the already measured measurement points as the next measurement point, for the current position and posture of the head of the user. Furthermore, the sound source position movement apparatus 1001 causes the acoustic signal generation unit 106 to move to the measurement point determined by the sound source position determination unit 104.

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