JP3374408B2 - Sound equipment - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention converts an input signal into a head related transfer function (HRTF).
The present invention relates to an acoustic device which is converted to binaural by using the.

[0002]

2. Description of the Related Art An acoustic device has been proposed in which an input signal is converted using a head acoustic transfer function to convert it into a binaural structure. That is, in this device, an acoustic signal for measurement (impulse sound) is emitted from a position (direction and distance) at which desired sound image localization is desired, and the head acoustic transfer function at that time is measured. The partial acoustic transfer function is stored. Then, the stored head acoustic transfer function is used to convert the input signal to perform binaural conversion.

However, in such an apparatus, when a large number of positions are desired for sound image localization, the head acoustic transfer function is measured at each of the positions, and the measured head acoustic transfer function is stored. Must. For this reason, the number of measurement steps is increased, and an extremely large memory capacity is required for storage. This application is made in view of such a point.

[0004]

The problem to be solved is that when there are many positions where sound image localization is desired,
This means that the number of measurement steps will increase and the memory capacity for storage will also need to be extremely large.

[0005]

A first means according to the present invention comprises a memory 1 storing a plurality of head acoustic transfer functions in association with an incident angle from a sound source, and at least two of the above-mentioned memories stored in the memory. The head-related acoustic transfer function is read, and each is converted into the frequency domain and decomposed into level characteristics and phase characteristics, and the obtained level characteristics and phase characteristics are interpolated by interpolation to obtain level characteristics corresponding to arbitrary angles. The phase characteristic is obtained, and the head acoustic transfer function is calculated from the obtained level characteristic and phase characteristic.
R) and conversion means (circuits 4L, 4R) for converting an input signal (signal source 5) into a binaural reproduction signal based on the head acoustic transfer function calculated by the calculation means. It is an audio device.

A second means according to the present invention comprises a memory 1 storing a plurality of head acoustic transfer functions measured in association with incident angles from a sound source, and at least two incident angles stored in the memory. The head-related acoustic transfer functions measured in association with each other are read out, converted into the frequency domain, decomposed into level characteristics and phase characteristics, and the obtained level characteristics and phase characteristics are interpolated by interpolation to obtain an arbitrary angle. And a phase characteristic corresponding to the above, and calculating means (arithmetic circuits 3L, 3R) for calculating a head acoustic transfer function from the obtained level characteristic and phase characteristic; An acoustic device comprising: a conversion unit (circuits 4L, 4R) for converting an input signal (signal source 5) into a binaural reproduction signal based on a head acoustic transfer function.

[0007]

According to this, by simply measuring and storing head acoustic transfer functions corresponding to a plurality of angles, binauralization of an arbitrary angle can be performed by calculation. The memory capacity can be reduced.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In FIG. 1, reference numeral 1 is a memory which stores left (L) and right (R) head acoustic transfer functions measured at a plurality of angles. Reference numeral 2 is a control circuit. A signal from the control circuit 2 is supplied to the memory 1 to read a head acoustic transfer function at a predetermined angle sandwiching an arbitrary angle for which sound image localization is desired. The head acoustic transfer functions read from the memory 1 are registered in the registers 21L, 22L,
And written in the registers 21R and 22R.

These registers 21L, 22L, and
The signals from the registers 21R and 22R are interpolated and
It is supplied to the interpolation calculation circuits 3L and 3R. Further, a signal for controlling the interpolation / interpolation ratio from the control circuit 2 is supplied to the arithmetic circuit
It is supplied to L and 3R, and interpolation / interpolation calculation is performed according to this ratio. Then, the head acoustic transfer function calculated by this calculation is supplied to the conversion circuits 4L, 4R, the signal from the input signal source 5 is converted, and the converted signals are supplied to the left and right headphones 6L, 6R.

That is, in this apparatus, for example, the head acoustic transfer function by the impulse sound source from the position A as shown in FIG. 2A and the head by the impulse sound source from the position B as shown in FIG. The partial acoustic transfer function is measured and stored in the memory 1. Then, interpolation / interpolation calculation is performed from these stored head acoustic transfer functions,
A head acoustic transfer function corresponding to the impulse sound source from the position C as shown in (c) is calculated, and binaural conversion corresponding to the sound source at the position C is performed using the calculated head acoustic transfer function. Be seen.

In the calculation of the interpolation / interpolation of the head acoustic transfer function, the above-mentioned measured / stored head acoustic transfer functions are each transformed into a frequency domain by orthogonal transformation, and further decomposed into levels and phases. Then, the interpolation / interpolation calculation is performed respectively. For example, as shown in FIG. 3, the level value of each head acoustic transfer function (h1 and h2) is proportionally divided. The same applies to the phase.

That is, for example, A and B in FIG. 4 are measurements of head-related acoustic transfer functions at 0 and 20 degrees. Therefore, if you perform 1: 1 interpolation / interpolation calculation for these,
The calculated head acoustic transfer function is as shown in A of FIG. 5, which is very close to B of the figure in which the head acoustic transfer function of 10 degrees is measured.

6A and 6B are 0 degree and 2 degrees, respectively.
Interpolation / interpolation calculations are performed on the head acoustic transfer function of 0 degrees at 1: 3 and 3: 1, which correspond to the head acoustic transfer functions of 5 degrees and 15 degrees.

Thus, according to the above-described device, only by measuring and storing head acoustic transfer functions corresponding to a plurality of angles, it is possible to perform binaural conversion of any angle by calculation (circuits 3L, 3R). The number of measurement steps and the capacity of the memory 1 for storage can be reduced.

When the interpolation processing is performed, there arises a problem of correspondence between which and where. In the above embodiment, the same frequency is used for simplicity. However, in the head acoustic transfer function, there is also a phenomenon in which the level peak and the dip shift in the frequency axis direction according to the change in the incident angle from the sound source. Therefore, strictly speaking, it is necessary to consider this frequency shift in association.

Also, the interpolation / interpolation calculation uses the linear interpolation method for simplicity in the above embodiment. It can be said that this is sufficient when the head acoustic transfer functions used for interpolation are very close to each other. However, when the head acoustic transfer functions used for interpolation are not very close to each other, it is more preferable to use the non-linear interpolation method according to the change of the head acoustic transfer functions.

Further, in the above apparatus, binauralization was performed using the interpolated / interpolated head acoustic transfer function and the measured head acoustic transfer function of A and B in FIG. I couldn't find a difference.
Further, comparative listening was performed at 20 to 90 degrees, but similar results were obtained, and the effectiveness of this method is confirmed. However, if the measurement has an angular interval of 30 degrees or more, the sound image is localized but the resolution is lacking. In that case, the countermeasures by improving the corresponding points and the interpolation method described above are effective.

[0018]

According to the present invention, by simply measuring and storing the head acoustic transfer functions corresponding to a plurality of angles, it is possible to perform binaural conversion of an arbitrary angle by calculation.
It has become possible to reduce the number of measurement steps and the memory capacity for storage.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an example of an audio device according to the present invention.

FIG. 2 is a diagram for explaining the explanation.

FIG. 3 is a diagram for explaining calculation of interpolation / interpolation.

FIG. 4 is a diagram showing an example of a head acoustic transfer function.

FIG. 5 is a diagram showing an example of an interpolated / interpolated head acoustic transfer function and a measured head acoustic transfer function.

FIG. 6 is a diagram illustrating another example of the interpolated / interpolated head acoustic transfer function.

[Explanation of symbols]

1 memory 2 control circuit 21L, 22L, 21R, 22R registers 3L, 3R interpolation / interpolation arithmetic circuit 4L, 4R conversion circuit 5 Input signal source 6L, 6R headphones

─────────────────────────────────────────────────── ─── Continuation of the front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) H04S 1/00

Claims (2)

(57) [Claims] 1. A memory in which a plurality of head acoustic transfer functions are stored in association with an incident angle from a sound source, and at least two head acoustic transfer functions stored in the memory are read out and converted into frequency domains. To obtain a level characteristic and a phase characteristic, and interpolate each obtained level characteristic and phase characteristic by interpolation to obtain a level characteristic and a phase characteristic corresponding to an arbitrary angle. And a conversion unit for converting an input signal into a binaural reproduction signal based on the head acoustic transfer function calculated by the calculation unit. Sound device. 2. A memory in which a plurality of head acoustic transfer functions measured in association with incident angles from a sound source are stored, and a head measured in association with at least two incident angles stored in the memory. Read out the acoustic transfer function,
Each is converted into a frequency domain and decomposed into level characteristics and phase characteristics. Interpolation is performed for each of the obtained level characteristics and phase characteristics to obtain a level characteristic and a phase characteristic corresponding to an arbitrary angle. Calculating means for calculating a head acoustic transfer function from the obtained level characteristic and phase characteristic; and converting means for converting an input signal into a binaural reproduction signal based on the head acoustic transfer function calculated by the calculating means. An acoustic device comprising: