JP2008160265A - Acoustic reproduction system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve problems that a mobile information terminal may be often used in a state held by a listener's hand and inclined back and force from the listener, differences in a distance between two speakers and the listener may be generated, a crosstalk canceling effect can not be obtained, a stereophonic sound field can not be provided, and since crosstalk cancel processing based on head transmission functions corresponding to the inclination of the mobile information terminal requires many head transmission function, a circuit scale may be increased. <P>SOLUTION: Two speakers in an acoustic reproduction system provided with a display screen for displaying an image and two speakers on the same surface and capable of changing an inclination and providing a stereophonic sound field to a listener by performing crosstalk cancel processing are arranged so that a straight line connecting the two speakers is made non-horizontal to the vertical direction of the display screen, a change in the positions of the two speakers corresponding to the inclination is detected by a means for detecting the inclination of an acoustic reproduction system housing, and a delay corresponding to the positional change is inserted into an output signal to the speakers. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention can be applied to a device such as a portable information terminal having a sound signal reproduction function, a desktop monitor, a liquid crystal monitor, etc., in which the display screen and two speakers are on the same surface and the tilt can be changed by the tilt function. The present invention relates to a sound reproduction system used.

  Conventionally, various methods for presenting a virtual three-dimensional sound field to a listener using two speakers have been considered. For example, in Japanese Patent Laid-Open No. 9-233600, a transfer characteristic (hereinafter referred to as a head-related transfer function) from a sound source position to be virtually localized to both ears of a listener is given to a sound source signal (hereinafter referred to as direction localization). And the crosstalk reproduced from the two speakers is prevented from reaching the listener's ears (hereinafter referred to as crosstalk cancellation processing), so that the sound source is at a desired position around the listener. The method of making the listener have an illusion as if there is a specific is shown.

  In recent years, it has become possible to enjoy contents distributed from the center and contents stored in advance in a memory card or the like in a three-dimensional sound field using such a method in portable information terminals such as mobile phones. ing.

  On the other hand, for example, in Japanese Patent Application Laid-Open No. 2005-295382, attention is paid to the fact that the localization position of a sound image can be changed in reproduction of an acoustic signal by two speakers, and two left and right arrangements with respect to the display unit are asymmetric. A method of operating a localization position of a sound image with respect to a video in a mobile phone equipped with a speaker is shown.

  Specifically, assuming that the portable information terminal is used in a portrait or landscape orientation, the display unit provided in the portable information terminal is rotated simultaneously with the relationship between the two speaker arrangements for the listener at that time. Thus, the direction localization processing is switched to localize the sound image of one or both speakers at a virtual position.

JP-A-9-233600 JP 2005-295382 A

  A sound reproduction system capable of providing a three-dimensional sound field by a conventional method is considered on the assumption that the positional relationship between the two speakers and the listener is fixed, and the head-related transfer function in that positional relationship is considered. Is used to cancel the crosstalk. When there are a plurality of positional relationships, it is necessary to prepare a head-related transfer function corresponding to each.

Further, this positional relationship is assumed to be invariant while the portable information terminal is being used in either the portrait orientation or the landscape orientation.
However, a portable information terminal characterized by a small size and light weight is often used while being held by a listener, or installed on a desk or the like, even when used in a specific orientation, In many cases, the listener is used in a state of being tilted in the front-rear direction. In such a case, if the two speakers are arranged asymmetrically as described above, a difference occurs in the positional relationship between the two speakers and the listener, that is, the distance. For this reason, the effect of canceling the crosstalk cannot be obtained, and there is a problem that a three-dimensional sound field cannot be presented to the listener.

  In addition, when considering crosstalk cancellation processing using a head-related transfer function uniquely obtained according to the inclination of the sound reproduction system housing, it is necessary to prepare a large number of head-related transfer functions in advance. is there. When the crosstalk cancellation processing is realized with a filter configuration, a huge memory is required to store all the filter coefficients, which increases the circuit scale.

  The present invention has been made to solve the above-described problems, and an object thereof is to provide an acoustic reproduction system that can present a highly effective three-dimensional sound field to a listener.

The sound reproduction system according to the present invention includes:
Sound reproduction that provides a display screen that displays an image and two speakers on the same plane, the display screen can be tilted, and a three-dimensional sound field is presented to the listener by applying crosstalk cancellation processing A system,
The two speakers are arranged so that the straight line connecting the two speakers is non-horizontal and non-vertical when the vertical direction of the display screen is vertical.
Means for detecting the attitude of the sound reproduction system housing and detecting the tilt of the housing;
Means for detecting a change in the position of the two speakers in accordance with the detected inclination;
Means are provided for inserting a delay into the output signal system to the speaker in accordance with the change in position.

  According to the sound reproduction system of the present invention, the difference in the sound source signal arrival time from the two speakers to the listener is caused by the inclination of the sound reproduction system housing, and the effect of canceling the crosstalk cannot be obtained according to the inclination. By inserting a delay into the output signal to the speaker, the head-related transfer function characteristics can be corrected, enabling precise crosstalk cancellation processing even when the sound reproduction system housing is tilted significantly. Thus, the listener can hear the sound image localized at the intended position.

  In the following, an embodiment of the sound reproduction system of the present invention will be described with reference to the drawings for a typical example of a portable information terminal. The present invention is not limited to the following portable information terminals. For example, the display screen and the speaker are on the same plane, such as a desktop monitor or a liquid crystal monitor, and the tilt is changed by the tilt function. It is possible to apply to an apparatus that can

Embodiment 1 FIG.
1 is a block diagram showing a configuration of a sound reproduction system for a portable information terminal according to Embodiment 1 of the present invention. In FIG. 1, 10 is a sound source unit, 100 is a sound image localization processing unit, and is composed of a direction localization unit 20 and a crosstalk cancellation unit 30. Reference numeral 40 denotes a playback unit, which includes two speakers.

  First, an outline of the operation will be described. The sound reproduction system of the portable information terminal according to the present embodiment has a single sound source signal or a plurality of sound source signals in the sound source unit 10, and inputs from the sound source unit 10 in the direction localization unit 20 constituting the sound image localization processing unit 100. Direction localization processing for localizing the sound image at a desired virtual position for each of the single or multiple sound source signals, and adding the plurality of sound source signals subjected to the direction localization processing to finally obtain two channels. Output as a stereo signal. Further, the crosstalk canceling unit 30 constituting the sound image localization processing unit 100 performs a filter process for canceling the crosstalk on the stereo signal obtained as a result of the direction localization processing. The output signal of the crosstalk canceling unit 30 is reproduced by two speakers constituting the reproducing unit 40, so that a three-dimensional sound field is reproduced for the listener.

  Next, details of the operation will be described. The sound source unit 10 has a single or a plurality of monaural sound sources, a general two-channel stereo sound source, or a so-called 5.1 channel surround sound source. These sound sources may be stored in a memory in advance, or may be downloadable by a music distribution service or the like. These sound sources are output to the sound image localization processing unit 100 as M channel (M> 0) sound source signals.

  The sound image localization processing unit 100 includes a direction localization unit 20 and a crosstalk cancellation unit 30. First, the direction localization unit 20 performs a direction localization process for localizing a sound image at a desired virtual position for each of the M channel sound source signals input from the sound source unit 10. The direction localization processing performed here is processing for making the listener feel a sound source in a specific direction and distance by adding characteristics such as signal level difference and time difference in both ears of the listener. There are many ways. An example is a binaural sound synthesis method.

  Binaural sounds are recorded as if there is a microphone near the human ear canal, and the sound at that location is recorded, and the recorded sound is played back with headphones at different locations. The sound recorded at this time is called binaural sound. Binaural sound is known to be characterized by the head-related transfer function from the sound source to both ears, and if the head-related transfer function from any direction and distance is obtained, the sound image can be localized at that position. Can do.

  The concept of the virtual position where the sound image is localized in the direction localization unit 20 is, for example, when the sound source signal stored in the sound source unit 10 is a stereo signal, compared to the actual interval between two speakers provided in the portable information terminal. Positions that provide a wide range of positions are defined as localization positions.

  Alternatively, when the sound source signal is a 5.1 channel surround signal, a general 5.1 channel speaker arrangement (left front, center, right front, left rear, right rear) is virtually localized. Position. Since the 0.1-channel signal is a low-frequency signal with a low localization feeling, the direction localization process can be omitted.

  The signals obtained as a result of the direction localization processing in this way are a signal group (L channel signal) that is considered to have reached the left ear from each virtual localization position, and a signal that is assumed to have reached the right ear. The signals are divided into groups (R channel signals) and subjected to addition processing for each signal group, and then output from the direction localization unit 20 as signals of two channels.

  Although the binaural sound synthesis method using the head-related transfer function has been described here, the direction localization processing in the present invention does not depend on a specific method, and other methods may be applied.

  By the way, it is assumed that the acoustic signal output from the direction localization processing unit 20 is a sound that is heard at the listener's ear, such as a binaural sound, as described above. For example, if playback is performed using headphones, it is possible to deliver two-channel acoustic signals directly to the listener's ears. However, when reproduction is performed by a speaker as in the sound reproduction system of the portable information terminal according to the present embodiment, it reaches from the left speaker to the listener's right ear and from the right speaker to the listener's left ear. So-called crosstalk occurs.

  FIG. 2 is a diagram illustrating a state in which an acoustic signal reproduced from a speaker arranged at the left front of the listener reaches both ears of the listener. A signal that is considered to have reached the listener's left ear is reproduced from the speaker. At this time, the signal SC that reaches the listener's right ear is crosstalk. The presence of this crosstalk is a factor that greatly impairs the sense of localization of the sound image, and it is necessary to cancel this. The signal SM reaching the listener's left ear is affected by the propagation characteristics from the speaker to the listener's left ear.

  The crosstalk canceling unit 30, which is another block constituting the sound image localization processing unit 100, generates a signal for canceling the above-described crosstalk and adds it to the output signal of the direction localization unit 20. Details of the crosstalk canceling unit 30 will be described later.

  The playback unit 40 includes two speakers for presenting the listener with a two-channel acoustic signal output from the sound image localization processing unit 100. In an actual apparatus, a D / A conversion unit, an amplifier, and the like are connected to the front stage of the speaker.

  FIG. 3 shows an example of the appearance of the portable information terminal according to this embodiment. The portable information terminal 200 includes a screen display unit 201, an antenna unit 202, and two speakers 4a and 4b. The screen display unit 201 has a rectangular shape, and is formed on the operation surface of the portable information terminal 200 such that each side of the screen display unit 201 is perpendicular or parallel to the vertical direction of the operation surface. In addition, an operation unit (not shown) is provided, but it is omitted because it is not related to the essence of the present invention.

  Here, the arrangement of the two speakers 4a and 4b will be mentioned. In the portable information terminal according to the present embodiment, the direction of the straight line connecting the two speakers is not perpendicular to the vertical direction of the image displayed on the screen display unit 201, and is not arranged in parallel. In FIG. 3A, the speaker 4 a that reproduces the L channel signal is arranged at the lower left part of the screen display unit 201, and the speaker 4 b that reproduces the R channel signal is arranged at the upper right part of the screen display unit 201. By arranging in this way, even when the portable information terminal 200 is rotated 90 degrees clockwise as shown in FIG. 3B, the two speakers are not arranged on the straight line in the vertical direction. No loss of function. Such an arrangement is called an asymmetric arrangement of speakers.

  The portable information terminal 200 is usually used by a listener holding it with one hand or both hands, or installed on a holder that also serves as a charger. In such a case, the two speakers 4a and 4b and the listener's both ears change from a reference position where there is a positional relationship.

  For example, FIG. 4 is a diagram illustrating a state in which the portable information terminal 200 is used with an inclination θ from the vertical direction, and is a viewpoint from the right side with respect to the portable information terminal 200. At this time, since the speakers are arranged asymmetrically, a difference of distance dL occurs between the listener and the two speakers 4a and 4b, and the speaker 4b that reproduces the R channel signal reproduces the L channel signal. It is farther than the speaker 4a. Hereinafter, for ease of explanation, it is assumed that the position of the speaker 4a is in the same position with respect to the listener depending on whether the speaker 4a is tilted or not. In addition, the case where there is no tilt, that is, the case where θ = 0 ° is considered as the reference position.

  Consider the head-related transfer function in the state as described above. FIG. 5 is a diagram showing a case where the portable information terminal 200 is used at the reference position. At this time, the two speakers 4a and 4b that are asymmetrically arranged on the portable information terminal 200 are located at almost equal distances from the listener. Here, hLL is a head-related transfer function from the speaker 4a located at the left front of the listener to the left ear of the listener, and hLR is a single head-related transmission from the speaker 4a to the right ear of the listener. Further, hRR is a head-related transfer function from the speaker 4b located at the right front of the listener to the listener's right ear, and hRL is a head-related transfer function from the speaker 4b to the listener's left ear.

  FIG. 6 is a plan view from the upper viewpoint showing a case where the portable information terminal 200 is used in a state tilted by the inclination θ. At this time, the two speakers 4a and 4b that are asymmetrically arranged on the portable information terminal 200 are located at positions different from the listener by a distance dL.

  Here, the head-related transfer function from the speaker 4a located at the left front of the listener to both ears of the listener is the same as when the positional relationship between the speaker 4a and both ears of the listener is the reference position. The head-related transfer function from the speaker 4a to the left ear is hLL, and the head-related transfer function from the speaker 4a to the right ear is hLR. On the other hand, the position of the speaker 4b located at the right front of the listener is changed by dL as compared with the reference position shown in FIG. Regarding the head-related transfer function at this time, hRR 'is the head-related transfer function from the speaker 4b to the listener's right ear, and hRL' is the head-related transfer function from the speaker 4b to the listener's left ear.

  Strictly speaking, when the portable information terminal 200 is tilted by the tilt θ, the direction (azimuth angle) of the speaker 4b as viewed from the listener also changes, and there is a variation in the distance associated therewith. However, this variation in distance is very small compared to the above-mentioned distance dL and can be ignored.

  The characteristics of the head-related transfer function are determined by the action of the transmission system in the space where the listener is present and the reflection system due to reflection, diffraction, and resonance by the listener's own head, face, auricle, shoulder, and the like. As a result of investigating the characteristics of the head related transfer functions hRR ′ and hRL ′ by experiment while changing the inclination θ of the portable information terminal 200 little by little, it has been found that the delay characteristics change most significantly. Yes. Therefore, in the crosstalk cancellation processing in the present embodiment, the head-related transfer functions hRR and hRL at the reference inclination are determined, and when the portable information terminal 200 is used at an inclination, the reference is determined according to the inclination θ. A delay was added based on the head related transfer functions hRR and hRL.

  FIG. 7 shows a circuit configuration of the crosstalk canceling unit 30 in the present embodiment. Reference numerals 1 a and 1 b denote input terminals for inputting two-channel acoustic signals from the direction localization unit 20. Here, it is assumed that 1a is an input terminal for an L channel signal and 1b is an input terminal for an R channel signal.

Reference numerals 2a, 2b, 2c and 2d denote filter units having different filter characteristics. The respective filter characteristics HLL, HLR, HRL, and RRR are as follows using the head-related transfer function as a reference.
HLL = hRR / (hLL · hRR−hLR · hRL) (Formula 1)
HLR = hLR / (hLL · hRR−hLR · hRL) (Formula 2)
HRL = hRL / (hLL · hRR−hLR · hRL) (Formula 3)
HRR = hLL / (hLL · hRR−hLR · hRL) (Formula 4)

  The signal adding unit 3a subtracts the output signal of the filter unit 2c from the output signal of the filter unit 2a. The signal adding unit 3b subtracts the output signal of the filter unit 2b from the output signal of the filter unit 2d.

  The inclination θ of the portable information terminal 200 is detected by the sensor 7 that is an inclination detecting means. This sensor 7 is used to detect a so-called posture angle, and is also called an inertial sensor, and includes a triaxial acceleration sensor, a triaxial geomagnetic sensor, a triaxial gyro, and the like.

  The distance correction unit 5 serving as the speaker position change detection means obtains the distance dL between the two speakers 4a and 4b according to the value of the inclination θ detected by the sensor 7, so that the time difference between the sound reaching the listener from the speakers is obtained. Is calculated. From this calculation result, an instruction signal for adjusting the time is output to the time adjusting units 6a and 6b as delay insertion means provided in the preceding stage of the speakers 4a and 4b.

  In the time adjustment units 6a and 6b, the sound source signals input from the signal addition units 3a and 3b are delayed in accordance with the instruction signal from the distance correction unit 5 and output to the speakers 4a and 4b of the playback unit 40 at the subsequent stage. Here, 9a and 9b are output terminals for outputting an acoustic signal to the reproducing unit 40.

A specific example of sound source signal delay processing will be described. When the inclination θ is 30 °, the distance dL that the speaker 4b fluctuates with respect to the reference position is
dL = 1/2 * L (Formula 5)
Here, L is the distance between the speakers in the vertical direction determined when the speakers are mounted on the main body.
The speaker 4b is located farther from the listener than the speaker 4a. At this time, a time difference dT corresponding to the distance dL occurs, and the sound that is simultaneously reproduced by the two speakers 4a and 4b is delayed in the time when the sound from the speaker 4b arrives. If the sound velocity is c [m / s], this time difference dT is
dT = dL / c (Formula 6)
It becomes.

FIG. 8 shows the distance L in the vertical direction when two speakers are mounted on the portable information terminal 200 in an asymmetric arrangement. If the linear distance between the two speakers is Lsp, and the angle formed by the vertical direction and the straight line connecting the two speakers is θsp, the distance L is L = Lsp * cos (θsp) (Equation 7)
Sought by. As can be seen from Equations 5 to 7, the time difference dT increases when the distance Lsp is large and the angle θsp is small. This is the case when speakers are arranged above and below the display screen, respectively.

  The distance correction unit 5 instructs the time adjustment unit 6a and the time adjustment unit 6b to insert a delay in consideration of the time difference dT obtained as described above and the positional relationship between the two speakers 4a and 4b. Output a signal. In the above case, since the time at which the sound from the speaker 4b arrives is delayed, an instruction signal is output so as to insert a delay corresponding to the time difference dT to the time adjustment unit 6a. At the same time, an instruction signal is output to the time adjustment unit 6b so that the delay to be inserted is zero.

  Further, the distance correction unit 52 shown in FIG. 13 configured so that the user can finely adjust the time difference dT obtained as described above may be used instead. When the user operates the user input unit 70, an offset for the time difference dT is given to the distance correction unit 52. The distance correction unit 52 outputs an instruction signal so as to insert a delay to the time adjustment units 6a and 6b after adding the given offset to the time difference dT.

  The crosstalk canceling unit 30 is not limited to the filter configuration as described above, and any other configuration can be used as long as it can cancel crosstalk that occurs during reproduction of an acoustic signal by two speakers. can do.

  In the above description, the case where the portable information terminal is used in the vertical direction is described. However, in the case where the portable information terminal is used in the horizontal direction, the distance between the left and right speakers as viewed from the listener is greatly different. The head-related transfer functions for both ears may be obtained and the filter characteristics HLL, HLR, HRL, and HRR may be switched.

  As described above, according to the sound reproduction system of the portable information terminal in the present embodiment, the inclination of the main body of the portable information terminal is detected, and the correction of the characteristics of the head-related transfer function from the two speakers to the listener's ears at that time Therefore, the listener can hear the sound image localized at the intended position without deteriorating the effect of canceling the crosstalk.

  In addition, since it is configured to correct the characteristics of the head related transfer function by inserting a delay with respect to the sound source signal according to the inclination of the portable information terminal, a head related transfer function assuming all inclinations is prepared. Therefore, the memory size for storing the filter coefficient does not increase, and the increase in circuit scale can be suppressed.

Embodiment 2. FIG.
FIG. 9 is a block diagram showing the configuration of the crosstalk cancellation unit 31 of the sound reproduction system of the portable information terminal according to the second embodiment of the present invention, which has a configuration different from that of the first embodiment. Note that the sound source unit 10, the direction localization unit 20, and the playback unit 40 shown in the first embodiment are not described in the configuration, function, and operation in the sound playback system of the portable information terminal according to the second embodiment. Omitted.

  The crosstalk cancellation unit 31 according to the present embodiment newly includes a determination unit 8 as a crosstalk cancellation calculation unit, and inputs information regarding the inclination of the portable information terminal from the sensor 7, and based on this, the filter unit 21a, Controls selection and switching of filter coefficients used in 21b, 21c, and 21d.

  For example, the inclination θ of the portable information terminal is divided into a plurality of sections, and a filter coefficient corresponding to an angle representing the inclination θ is prepared for each section. 10 and 11 are examples of a classification table showing the relationship between the inclination θ, the classification, and the representative angle. FIG. 10 shows a case where the range of 0 ° to 90 ° is equally divided into three sections with respect to the inclination θ. It is assumed that the filter coefficient used for the category 1 is obtained from the head-related transfer function when the inclination of the main body is 0 °. FIG. 11 shows a case where the range of 0 ≦ dL ≦ L is equally divided into three sections with respect to the distance dL. It is assumed that the filter coefficient used for the category 1 is obtained from the head-related transfer function when the inclination of the main body is 0 °.

  As for the classification table, the distance correction unit 51 and the determination unit 8 have the same classification table. The method for setting the classification is not limited to the above-described method, and the number of settings for the classification is not limited to three, and can be set to N (an integer where N> 0).

  The determination unit 8 determines a corresponding category from the category table according to the value of the inclination θ detected by the sensor 7. Furthermore, the information of this division is output to the filter units 21a, 21b, 21c, and 21d. Each filter unit selects a filter coefficient based on the classification information and executes a filter process. Since the configuration and operation of each filter unit are the same, here, the filter unit 21a will be described as a representative.

  FIG. 12 is a diagram showing the configuration of the filter unit 21a. When the classification is given by the determination unit 8, the filter unit 21a switches to filter processing using the corresponding filter coefficient using the classification information as an index. When the index is 1, HLL_1 is selected, and when the index is 2, HLL_2 is selected.

  Further, the information on the inclination θ from the sensor 7 in FIG. The distance correction unit 51 obtains the distance dL between the two speakers 4a and 4b according to the value of the inclination θ. At the same time, a distance difference in inclination representing the classification is obtained based on the classification table, and this difference is regarded as a substantial distance difference. Based on this substantial distance difference, the time difference for the sound to reach the listener from the speaker is calculated. From this calculation result, an instruction signal for adjusting the time is output to the time adjusting units 6a and 6b provided in the previous stage of the speakers 4a and 4b.

  The time adjustment units 6a and 6b delay the sound source signals input from the signal addition units 3a and 3b in accordance with the instruction signal from the distance correction unit 51 and output the delayed sound source signals to the speakers 4a and 4b of the playback unit 40 at the subsequent stage. Here, 9a and 9b are output terminals for outputting signals to the reproducing unit 40.

  A specific example is shown. When the inclination θ = 30 °, the distance dL between the two speakers with respect to the listener is as shown in (Equation 5). When this inclination θ = 30 °, for example, when FIG. And at the boundary of Category 2. When the detected inclination is present at the boundary, it is determined that the section 2 which is a section having a large inclination is selected. The classification information output from the determination unit 8 is 2. At this time, the filter unit 21a uses the filter coefficient HLL_2. Similarly, filter coefficients are selected in the filter units 21b, 21c, and 21d.

  The distance correction unit 51 obtains the distance dL and, at the same time, obtains a distance difference in the case of an inclination of 30 ° representing the category 2 based on the category table, and calculates a substantial distance difference dL ′. In the case of θ = 30 °, since it is the same as the representative inclination of 30 °, dL ′ is zero, and the time difference corresponding to this is zero. As a result, the instruction signal is output so that the delay to be inserted into the time adjustment units 6a and 6b is zero.

  On the other hand, when the inclination θ = 45 °, for example, when the classification table of FIG. The determination unit 8 outputs the classification information to all the filter units. In accordance with this information, the filter unit 21a uses the filter coefficient HLL_2. Similarly, filter coefficients are selected in the filter units 21b, 21c, and 21d.

The distance correction unit 51 obtains the distance dL between the two speakers with respect to the listener.
dL = 1 / √2 * L (Formula 8)
At the same time, the distance in the case of an inclination of 30 ° representing the category 2 with θ = 45 ° is obtained from the category table, and the substantial distance difference dL ′ is calculated. From (Expression 5) and (Expression 8), it is as follows.
dL ′ = (1 / √2−1 / 2) L (Formula 9)

  Then, in consideration of the time difference dT ′ corresponding to the substantial distance difference dL ′ and the positional relationship between the two speakers 4a and 4b, an instruction signal is inserted so as to insert a delay into each of the time adjustment units 6a and 6b. Is output. The method for obtaining the time difference dT ′ is the same as in the first embodiment. In the above case, since the time when the sound from the speaker 4b reaches the listener is delayed, an instruction signal is output so as to insert a delay corresponding to the time difference dT 'to the time adjustment unit 6a. At the same time, an instruction signal is output to the time adjustment unit 6b so that the delay to be inserted is zero. As described in the first embodiment, the distance correction unit 51 may be configured such that the user can adjust the time difference dT ′.

  In the above description, the case where the portable information terminal is used in the vertical direction is described. However, in the case where the portable information terminal is used in the horizontal direction, the distance between the left and right speakers as viewed from the listener is greatly different. The head-related transfer functions for both ears may be obtained and the filter characteristics HLL, HLR, HRL, and HRR may be switched.

  As described above, according to the sound reproduction system of the portable information terminal in the present embodiment, the plurality of filter coefficients are switched according to the inclination of the main body of the portable information terminal divided into the plurality of sections, and at the same time, the gradient for each stepwise section. The correction of the characteristics of the head-related transfer function based on the difference between the actual tilt and the actual tilt is performed by inserting a delay with respect to the sound source signal. Processing is possible, and the listener can hear a sound image localized at the intended position.

  In the above embodiment, the timing for determining the inclination θ is, for example, when the switch operated by the listener is turned on in order to enable three-dimensional sound reproduction, or the fluctuation of the inclination during the reproduction is within a specified range. The point of time within which the mobile information terminal falls within can be mentioned, but various determinations can be made according to the usage mode in which the portable information terminal according to the present invention is used.

Embodiment 3 FIG.
FIG. 14 is a diagram showing an asymmetric arrangement of two speakers in the sound reproduction system for a portable information terminal according to Embodiment 3 of the present invention. The two speakers 4a and 4b are arranged such that the angle θsp formed by the top-and-bottom direction of the screen display unit 201 and the linear direction connecting the two speakers 4a and 4b is 45 °.

  FIG. 14A shows a state in which the portable information terminal according to the present embodiment is used in the portrait orientation, and FIG. 14B shows a state in which the portable information terminal according to the present embodiment is used in the landscape orientation. . In both cases, the distance Lh between the left and right speakers is equal to the top-to-bottom direction of the screen display unit 201, and Lh = 1/2 * Lsp.

  When the two speakers are arranged in this way, the distance between the left and right speakers as seen by the listener does not change, so there is no need to obtain different head-related transfer functions in the vertical and horizontal directions, and the filter characteristics. There is no need to switch between HLL, HLR, HRL, and HRR between the portrait orientation and the landscape orientation.

  As described above, according to the sound reproduction system of the portable information terminal in the present embodiment, even when the portable information terminal is used in the portrait orientation or the landscape orientation, the distance between the left and right speakers viewed from the listener can be made the same. It is not necessary to apply different head-related transfer functions in the talk cancellation process, it is possible to avoid an increase in the memory size for storing the filter coefficients, and an increase in circuit scale can be suppressed.

  In each of the above embodiments, the case where the sound reproduction system of the present invention is applied to a portable information terminal has been described. However, as described above, the application is not limited to only a portable information terminal, such as a desktop monitor or a liquid crystal monitor. Similarly, it goes without saying that the present invention can be applied to a device in which the display screen and two speakers are on the same plane and the tilt can be changed by the tilt function.

  The sound reproduction system of the present invention can perform crosstalk cancellation processing precisely even when the housing of the apparatus is used at an angle, and there are many scenes where the case is used at an angle, for example, a mobile phone, acoustic communication with the outside It can be applied to portable information terminal devices such as portable game machines and devices such as a desktop monitor and a liquid crystal monitor, etc., and a device whose display screen and speaker are on the same plane and whose tilt can be changed by a tilt function. Is possible.

1 is a configuration block diagram of a sound reproduction system for a portable information terminal that is Embodiment 1 of the present invention. FIG. It is explanatory drawing of a mode that a reproduction | regeneration acoustic signal reaches | attains a listener's both ears from a speaker. 3 is an external view illustrating an example of a portable information terminal according to Embodiment 1. FIG. It is a right view of the state in which a portable information terminal is used with inclination. It is use condition explanatory drawing in a portable information terminal in a standard position. It is a top view of the state in which a portable information terminal is used with inclination. 3 is a circuit diagram of a crosstalk canceling unit in the first embodiment. FIG. It is explanatory drawing of the distance of the top-and-bottom direction between two speakers asymmetrically arranged in the portable information terminal. It is a circuit diagram of the crosstalk cancellation part in Embodiment 2 of this invention. It is explanatory drawing of the relationship between the inclination which divided | segmented the inclination of a portable information terminal equally, and a representative value. It is explanatory drawing of the relationship between the inclination and the representative value which equally divided the distance difference to a listener produced at the time of inclination of a portable information terminal. 6 is a block diagram illustrating a configuration of a filter unit according to Embodiment 2. FIG. It is a block diagram of the distance correction | amendment part comprised so that a user could adjust the amount of acoustic signal delays. It is asymmetric arrangement explanatory drawing of two speakers in the sound reproduction system of the portable information terminal by Embodiment 3 of this invention.

Explanation of symbols

  2a, 2b, 2c, 2d, 21a, 21b, 21c, 21d; filter unit, 3a, 3b; signal addition unit, 4a, 4b; speaker, 5, 51, 52; distance correction unit, 6a, 6b; time adjustment unit 7; Sensor; 8; Determination unit, 9a, 9b; Output terminal, 10; Sound source unit, 20; Direction localization unit, 30, 31; Crosstalk cancellation unit, 40; Playback unit, 70; User input unit, 100; Sound image localization processing unit 200; portable information terminal 201; screen display unit 202; antenna unit.

Claims (4)

Sound reproduction that provides a display screen that displays images and two speakers on the same plane, the display screen can be tilted, and a three-dimensional sound field is presented to the listener by applying crosstalk cancellation processing A system,
The two speakers are arranged so that the straight line connecting the two speakers is non-horizontal and non-vertical when the vertical direction of the display screen is vertical.
Means for detecting the attitude of the sound reproduction system housing and detecting the tilt of the housing;
Means for detecting a change in the position of the two speakers in accordance with the detected inclination;
A sound reproduction system comprising means for inserting a delay into an output signal system to a speaker in accordance with the change in position.   Crosstalk cancellation calculation means for selecting a head-related transfer function corresponding to the detected change in the position of the two speakers and performing a calculation for crosstalk cancellation is provided. The sound reproduction system according to claim 1, wherein the sound reproduction system is performed based on a transfer function.   3. The sound reproduction system according to claim 1, wherein the means for inserting a delay into the output signal system is configured such that a listener can adjust the delay amount.   The display screen is formed so that two sides are parallel to the top and bottom direction, and the two speakers extend outside the display screen, and a straight line connecting the two speakers and the two speakers extend horizontally and vertically with respect to the display screen. The sound reproduction system according to any one of claims 1 to 3, wherein an angle at which the line intersects is 45 degrees.

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