JP2007251831A - Sound image localizing apparatus, and sound image localizing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sound image localizing apparatus and a sound image localizing method wherein a regulation amount of a volume control and a localizing position of a sound image are linearly changed. <P>SOLUTION: The sound image localizing apparatus includes: an angle detection section 23 for detecting an angle of the sound image to be localized between a front speaker and a surround speaker; and an output level arithmetic section 25 for calculating a rate of a sound volume distributed on the basis of the localizing angle of the sound image. The output level arithmetic section 25 calculates an output level by taking into account a correction parameter acquired from a parameter acquisition section 24. The correction parameter is expressed in a consecutive curve so that a distribution rate to the front speaker is decreased when the sound image is localized at an angle in front from a side of a listener and the distribution rate to the front speaker is increased when the sound image is localized at an angle at the back from the side of the listener. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a sound image localization apparatus and a sound image localization method that determine a localization position of a sound image by distributing sound volumes output from two speakers, a front speaker and a surround speaker.

  In a digital audio apparatus that reproduces an N channel (N> 5) input signal using a 5 channel (including 5.1 channel) surround signal, when an input signal of a channel different from the angle of the output channel is given, It is necessary to localize the sound image at an angle corresponding to the input signal by adjusting the output signal from the playback speaker

  For example, in a multi-channel input signal, an original sound from a speaker (such as left and right horizontal speakers and a back center speaker) that does not exist in 5 channels controls output from 5 channel speakers arranged on both sides thereof. This creates a situation as if sound is being output from that part.

As such a sound image localization method, as shown in Patent Document 1 or the like, a method called intensity stereo for phantom localization of a sound source by a level difference between left and right speakers, or a preceding sound effect called a Haas effect is used. In order to achieve this, a method for adding a delay between the outputs of the left and right speakers is known. Such sound image localization is used not only for the left and right stereo speakers but also for sound image localization in the front-rear direction in a surround system represented by 4 channels or 5.1 channels.
JP 2002-345097 A

  FIG. 7 shows an example of the case where the sound source is phantom localized by the level difference between the left and right speakers L and R, and the output from the left and right speakers (for example, the power sum) is always constant. The sound image is localized at an arbitrary position between the left and right speakers by increasing or decreasing the outputs of the left and right speakers.

  However, when the sound image is localized by adjusting the outputs of the left and right speakers L, R arranged in front of the listener as shown in FIG. 7, conventionally, the localization angle of the sound image and the left and right speakers L, R, The level difference between R was almost linearly proportional (or a curve curved in one direction as shown in FIG. 7). That is, the closer the angle of the localized sound image is to one speaker, the larger the output from that speaker, and the distribution rate of the output from one speaker is linear or unidirectional as the angle of the localized sound image approaches the other speaker It was enlarged along the curved curve.

  Certainly, in this method, since the left and right ears of the listener facing the front face the two speakers in front, the distribution ratio of the speaker output is directly proportional to the localization position of the sound image and is excellent in the sense of localization of the sound image. There is an advantage.

  However, when such a method is applied to speakers in the front-rear direction of 5 channels as shown in FIG. 8, for example, between the left front speaker and the left surround speaker, and between the right front speaker and the right surround speaker. Since the position of the listener's ear is not directly facing the front speaker and the surround speaker, there arises a problem that the sound image cannot be localized at the intended angle.

  For example, when the front speaker L or R is disposed 30 ° ahead of the listener and the surround speaker SL or SR is disposed 120 ° rearward of the listener and the same sound volume level is output from both speakers, it is normally 75. Although the sound image should be localized in the vicinity of °, the listener has the impression that the sound image is localized in the vicinity of 45 to 50 °.

  Therefore, when the volume of the two speakers is adjusted using a rotary or slide volume, the position of the sound image does not change linearly in proportion to the volume, and the sound image is localized at a desired position. It becomes difficult to let you.

  The present invention has been proposed in order to solve the above-mentioned problems of the prior art, and its purpose is to correct the volume level output from the front speakers and the surround speakers according to the auditory characteristics of the listener. Accordingly, it is an object to provide a sound image localization apparatus and a sound image localization method in which the localization position of a sound image changes linearly in proportion to the volume of two speakers and the localization operation can be easily performed.

  In order to achieve the above object, the present invention provides a sound image localization apparatus that determines a localization position of a sound image by allocating sound volumes output from two speakers, a front speaker and a surround speaker. Compared to the angle detector that detects the angle of the sound image to be localized between and the distribution ratio to the front speakers that is linearly proportional to the angle between the front speakers and the surround speakers, When the sound image is localized at the front angle, the distribution ratio to the front speaker is small, and when the sound image is localized at a rear angle from the side of the listener, the distribution ratio to the front speaker is large. The linear distribution ratio at an intermediate angle between the speaker and the listener's side and an intermediate angle between the listener's side and the surround speaker. A parameter acquisition unit that acquires a correction parameter represented by a continuous curve with a large separation from the distribution rate to the front speaker; and a front speaker based on the localization angle of the sound image detected by the angle detection unit; And an output level calculation unit that performs calculation processing in consideration of the correction parameters acquired from the parameter acquisition unit when calculating the volume ratio to be distributed to the surround speakers.

  Further, the parameter output unit is configured such that the amount of separation between the distribution rate to the front speaker that is linearly proportional to the angle and the distribution rate to the front speaker in front of the listener is to the front speaker that is linearly proportional to the angle. The volume of the front speaker and the surround speaker is set to be larger than the amount of separation between the distribution rate and the distribution rate to the front speakers behind the listener, and at each sound image localization angle arranged between the two speakers. It is also an aspect of the present invention that the sum is determined based on the energy distribution indicated by the sine-square curve.

  Furthermore, a sound image localization method for determining the proportion of the volume distributed to the front speaker and the surround speaker using the correction parameter as described above is also an aspect of the present invention.

  That is, as shown in FIG. 2, according to the experiment of the present inventor conducted for a plurality of subjects (Subject 1-5), the distribution ratio to the front speakers and the localization position of the sound image are not linearly proportional, Compared with the distribution rate P to the front speakers that is linearly proportional to the angle between the front speakers and the surround speakers, the distribution rate to the front speakers is higher when the sound image is localized forward than the side of the listener. If the sound image is smaller and the sound image is localized behind the listener's side, the distribution ratio to the front speakers increases, the angle between the front speaker and the listener's side, and the listener's side and surround speakers. It has been found that the intermediate curve is represented by a continuous curve Q that maximizes the difference between the linear distribution ratio and the distribution ratio to the front speakers.

  Further, the amount of separation L1 between the distribution rate P to the front speakers that is linearly proportional to the angle and the distribution rate Q to the front speakers in front of the listener is the distribution rate P to the front speakers that is linearly proportional to the angle. It was also confirmed that the distance L2 was set larger than the distance L2 from the distribution rate Q to the front speakers behind the listener.

  Therefore, in the sound image localization apparatus and the sound image localization method of the present invention having the above-described configuration, by determining the volume ratio between the front speaker and the surround speaker based on the distribution ratio indicated by the curve Q as described above. The volume adjustment amount and the localization position of the sound image change linearly.

  According to the present invention, by using the correction parameters as described above, the volume adjustment amount and the sound image localization position change linearly, and the sound image localization position can be intuitively grasped. Becomes easier.

(1) First Embodiment FIG. 1 shows a first embodiment of the present invention, in which an audio signal from the sound source 10 is output to a plurality of speakers (a 5.1 channel speaker group as an example). In this case, a localization angle of a sound image is input from an input device 11 such as a keyboard, an encoder, another computer or a control panel, and the input localization angle is detected by the angle detection unit 12 and is approached according to the detected angle. The sound image is localized by adjusting the volume from the two speakers.

  That is, as the sound source 10, an 8-channel or other multi-channel sound source that cannot be directly output from a 5-channel speaker is used, or a sound source of 5 channels or less, and its localization position is set to each of the 5-channel speakers. Use a sound source that needs to be localized during

  The input device 11 and the angle detection unit 12 connected to the input device input to which angle of each speaker of 5 channels (which position between the speakers) the sound signal from the sound source 10 is input, and The input angle is detected and output to the next parameter acquisition unit 13.

  The parameter acquisition unit 13 corresponds to the sound image position to be localized based on the angle detected as described above and the parameter determination curve Q as shown in FIG. 2 prepared in advance. Get the parameter.

  The output level calculator 14 calculates the output levels of the front speaker L and the surround speaker SL on the left side of the listener and the front speaker R and the surround speaker SR on the right side of the listener in accordance with the parameters obtained as described above. . For example, when the detection angle is 90 °, 0.33 corresponding to 90 ° on the horizontal axis in FIG. 2, 0.32 when the angle is 40 °, and 0.62 when the angle is 110 degrees. Obtains 0.17 as the distribution rate of the front speakers L.

  Then, the input signal L for the left front speaker from the sound source is based on the distribution ratio obtained as described above and the energy ratio of the front speaker and the surround speaker corresponding to each distribution ratio as shown in FIG. Thus, the level of the output signal L from the 5-channel front speaker is determined. That is, in the present embodiment, energy distribution is performed using the sine-square curve shown in FIG. 6 so that the sum of the outputs of the front speaker and the surround speaker is constant. The sound volume level output from each speaker is determined by obtaining the energy distribution to each speaker corresponding to the distribution ratio from the curve in FIG.

  On the other hand, as a result of determining the angle, the distribution ratio of the output signal SL from the surround speakers of the five channels is also obtained from the curve Q in FIG. 2 so that the sum of the outputs of the surround speakers and the front speakers is constant. Therefore, based on the obtained distribution ratio and the energy distribution shown in FIG. 6, the 5-channel surround speaker output signal SL can be obtained from the left surround speaker input signal SL from the sound source 10.

  Similarly, for the right front speaker R and surround speaker SR from the sound source 10, the parameters obtained from the graph of FIG. 2 are considered in accordance with the localization angle of the sound image obtained by the angle detection unit 12. The output level is calculated and output from the front speaker R and the surround speaker SR via the output unit 15.

  As described above, in the first embodiment, correction parameters having different values are acquired in accordance with the localization angle of the sound image, and the volume distribution ratio of the front speakers and the surround speakers is determined in consideration of the correction parameters. As a result, the volume of the front speaker is corrected in a smaller direction compared to the prior art, and sound image localization close to the result of the listening experiment by the listener is realized. In addition, compared to the conventional technique in which the volume distribution ratio is linearly changed, it is possible to evenly assign the operation amount such as the volume with respect to the localization angle of the sound image.

(2) Second Embodiment A second embodiment of the present invention will be specifically described with reference to the functional block diagram of FIG. 3 and the flowchart of FIG. Note that in the flowchart of FIG. 4 and the following description, only the left speakers of the 8-channel and 5-channel are shown, but the right speaker operates in the same manner. FIG. 5 is a plan view showing an example of an 8-channel and 5-channel speaker arrangement in the present embodiment.

  3, reference numeral 21 denotes a sound source input unit, which is configured to input an 8-channel sound source in this embodiment (step 01 in FIG. 4). Reference numeral 22 denotes a correlation determination unit that examines the correlation of sound sources from adjacent three channels input from the sound source input unit 21, and as an example, from each channel of the front speaker L, the horizontal speaker ML, and the surround speaker SL. Are subjected to Fast Fourier Transform (FFT) and the converted values are compared, whereby the correlation between the input signal L from the front speaker and the input signal ML from the horizontal speaker, and the input signal ML from the horizontal speaker The correlation of the input signal SL from the surround speaker is determined (step 02 in FIG. 4).

Reference numeral 23 denotes an angle detection unit which determines the localization position (angle) of the sound image as follows according to the presence or absence of correlation by the correlation determination unit 22 (FIG. 4). Step 03).
(1) Localization position (localization angle) of sound image when there is no correlation between input signals ML and MR from horizontal speakers and input signals L and R from front speakers or input signals SL and SR from surround speakers Is 90 ° (the position of the horizontal speaker ML).
(2) When there is a correlation between the input signal ML from the horizontal speaker and the input signal L from the front speaker or the input signal SL from the surround speaker, the input signal ML from the horizontal speaker and the input signal from the front speaker The localization position (angle) of the sound image is determined from the ratio of the average value of the amplitude to the input signal SL from the L or surround speaker.

  Reference numeral 24 denotes a parameter acquisition unit. The parameter acquisition unit 24 determines a sound image position to be localized based on the angle determined as described above and a parameter determination curve Q as shown in FIG. Is obtained (step 04 in FIG. 4).

  Reference numeral 25 denotes an output level calculation unit, which calculates the output levels of the front speaker L and the surround speaker SL according to the parameters obtained as described above. For example, when the angle is 90 °, 0.33 corresponding to 90 ° on the horizontal axis in FIG. 2, 0.32 when the angle is 40 °, and 0.62 when the angle is 110 degrees. 0.17 is acquired as the distribution rate of the front speakers L.

  Then, based on the distribution ratio obtained as described above and the energy ratio of the front speaker and the surround speaker corresponding to each distribution ratio as shown in FIG. 6 to the input signal L from the 8-channel front speaker, The level of the output signal L from the 5-channel front speaker is determined (step 05 in FIG. 4). That is, in the present embodiment, energy distribution is performed using the sine-square curve shown in FIG. 6 so that the sum of the outputs of the front speaker and the surround speaker is constant. The sound volume level output from each speaker is determined by obtaining the energy distribution to each speaker corresponding to the distribution ratio from the curve in FIG.

  On the other hand, as a result of determining the angle, the distribution ratio of the output signal SL from the surround speakers of the five channels is also obtained from the curve Q in FIG. 2 so that the sum of the outputs of the surround speakers and the front speakers is constant. Therefore, based on the obtained distribution ratio and the energy distribution of FIG. 6, the output signal SL of the 5-channel surround speaker can be obtained from the input signal SL of the 8-channel surround speaker (step 06 in FIG. 4). ).

  The output signals of the front speaker L and the surround speaker SL obtained by the output level calculation unit 25 as described above are output to the corresponding speakers of 5 channels in the output unit 26. For example, when the localization angle of the sound image is 40 °, in the conventional technique, the distribution rate is set to 0.89, and the outputs of the front speakers and the surround speakers corresponding to the distribution rate of 0.89 are obtained from FIG. In the present embodiment, the distribution rate is 0.62, and the outputs of the front speakers and the surround speakers corresponding to the distribution rate 0.62 are obtained from FIG. As a result, the volume of the front speaker is corrected in a smaller direction compared to the prior art, and a sound image localization close to the result of the listening experiment by the listener is realized.

  According to the present embodiment having the above-described configuration, correction parameters having different values are acquired in accordance with the localization angle of the sound image, and the volume distribution ratio of the front speakers and the surround speakers is taken into consideration with the correction parameters. Therefore, as compared with the prior art in which the volume distribution ratio is linearly changed, it is possible to evenly assign the operation amount such as the volume with respect to the localization angle of the sound image.

In particular, in this embodiment, the curve Q in FIG.
(1) The curve is asymmetric with respect to the center.
(2) The slope of the curve is flat near the center.
As a result, the localization of the sound image becomes more natural for the listener, and the movement of the sound image near the center is slowed down, making it easier to localize the sound image near the center. is there.

(3) Other Embodiments The present invention is not limited to the above-described embodiment. For example, the curve Q for determining the correction parameter is appropriately changed according to the arrangement angle between the front speaker and the surround speaker. Is possible. In that case, a new curve Q can be determined by conducting a listening experiment with a large number of listeners in accordance with the arrangement angle of the speakers. In addition, the amount of separation between the curve Q and the curve P is changed according to the environment such as the type of sound to be reproduced and the recording location, or the position of the intersection of the curves P and Q provided on the side of the listener is changed. It is also possible to do. Further, the original sound as a source is not limited to eight channels, and can be applied to all reproduction systems having two or more speakers.

  As described above, the present invention is also used for obtaining angle data input by an operator, or when the sound source data is not a multi-channel such as 8 channels but a single sound source is localized at a specific position. Is possible.

1 is a block diagram showing a first embodiment of the present invention. The graph which shows the curve which determines the parameter of the distribution rate used for this invention. The block diagram which shows the structure of 2nd Embodiment of this invention. The flowchart which shows operation | movement of 2nd Embodiment of FIG. The top view which shows the localization of the sound image between a front speaker and a surround speaker in a 5-channel surround system. The graph which shows energy distribution in case the sum of the volume of a front speaker and a surround speaker is made constant. The top view which shows the localization of the sound image between the left and right front speakers. The top view which shows the state which reproduces | regenerates the 8-channel original sound with a 5-channel surround system.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Sound source 11 ... Angle input part 12 ... Angle detection part 13 ... Parameter acquisition part 14 ... Output level calculation part 15 ... Output part 21 ... Sound source input part 22 ... Correlation determination part 23 ... Angle detection part 24 ... Parameter acquisition part 25 ... Output level calculation unit 26 ... output units L, R ... front speakers ML, MR ... horizontal speakers SL, SR ... surround speakers C ... center speakers BC ... rear center speakers

Claims (4)

In a sound image localization apparatus that determines a localization position of a sound image by allocating sound volumes output from two speakers, a front speaker and a surround speaker,
An angle detector for detecting the angle of the sound image to be localized between the front speaker and the surround speaker;
Compared to the distribution ratio to the front speaker that is linearly proportional to the angle between the front speaker and the surround speaker, the distribution ratio to the front speaker when the sound image is localized at an angle ahead of the listener's side. When the sound image is localized at a rear angle from the listener's side, the distribution ratio to the front speakers increases, and the angle between the front speaker and the listener's side and the listener's side A parameter acquisition unit that acquires a correction parameter represented by a continuous curve in which the amount of separation between the linear distribution rate and the distribution rate to the front speaker is large at an intermediate angle between the speaker and the surround speaker;
An output level for performing a calculation process in consideration of the correction parameter acquired from the parameter acquisition unit when calculating the ratio of the volume distributed to the front speaker and the surround speaker based on the localization angle of the sound image detected by the angle detection unit An arithmetic unit;
A sound image localization apparatus comprising:   The parameter output unit distributes the front speaker in which the amount of separation between the distribution rate to the front speaker that is linearly proportional to the angle and the distribution rate to the front speaker in front of the listener is linearly proportional to the angle. The sound image localization apparatus according to claim 1, wherein the sound image localization apparatus is set to be larger than a separation amount between the distribution ratio to the front speaker and the rear part of the listener.   The sum of the sound volume of the front speaker and the surround speaker is determined based on the energy distribution indicated by the sine-square curve at each sound image localization angle arranged between the two speakers. Item 3. The sound image localization apparatus according to Item 2. In a sound image localization method for determining a localization position of a sound image by allocating sound volumes output from two speakers so that a sum of sound volumes output from two speakers, a front speaker and a surround speaker, is constant.
Detecting an angle of a sound image to be localized between the front speaker and the surround speaker;
In adjusting the volume of the front speaker and the surround speaker based on the localization angle of the sound image detected by the step of detecting the angle, the ratio of the volume distributed to the front speaker and the surround speaker is taken into consideration in the correction parameter. And determining a step,
The step of determining a volume ratio to be distributed to the front speaker and the surround speaker in consideration of the correction parameter is compared with a distribution ratio to the front speaker that is linearly proportional to an angle between the front speaker and the surround speaker. Therefore, the distribution rate to the front speaker is small when the sound image is localized forward of the listener's side, and the distribution rate to the front speaker is determined when the sound image is localized behind the listener's side. In the intermediate angle between the front speaker and the listener's side and the intermediate angle between the listener's side and the surround speaker, the amount of separation between the linear distribution ratio and the distribution ratio to the front speaker is A sound image localization method characterized in that the sound image localization method is performed based on a parameter represented by a continuous curve that has increased.