JPH0832117B2 - Sound quality evaluation device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a sound quality evaluation apparatus used for evaluation of audio equipment.

Conventional technology In recent years, with the advent of CDs, ATs, etc., the dynamic range has expanded,
The sound quality is improved by reducing the distortion rate and flattening the frequency characteristic, and the small signal reproduction technology has been developed. At the same time, it has been important to evaluate the high-quality sound reproduced by the technique. Conventionally, as a method for evaluating the sound quality of various audio equipment such as a speaker, an auto Wigner distribution (JAE ES 31 Vol. 4 (1983)
(Year) (JAES, VOL.31, No.4 (1983)). ).

An example of conventional evaluation of a speaker will be shown. The result of adding the impulse response of the speaker at the listening point and adding the output of the Auto Wigner distribution calculated using it at an arbitrary time is illustrated every time.
(Hereinafter, referred to as cumulative power distribution) FIG. 6 is an evaluation result based on the cumulative power distribution of the speaker. The X-axis shows frequency, the Y-axis shows time, and the Z-axis shows power. It can be seen what kind of frequency component signal remains in the time direction. In addition, the sound quality evaluation result in the trial listening experiment can be explained from the physical characteristics.

Problems to be Solved by the Invention In the physical evaluation based on the above cumulative power distribution, a signal can be analyzed in frequency and time, which can be linked to evaluation by hearing. However, even if the signal can be analyzed, the directionality of the signal is not known, so that there is a problem that it is difficult to analyze the signal source that is considered to affect the sound quality as a difference in hearing.

In view of the above problems, the present invention provides a sound quality evaluation apparatus that analyzes a three-dimensional component of a transient response characteristic of power of an input signal and three-dimensionally displays each component.

Means for Solving the Problems In order to solve the above-mentioned problems, microphones are provided with acoustic signals at two points separated by a constant distance in each of a total of three directions, that is, a straight line direction connecting a listening point and a signal source and directions orthogonal to each other. The input means obtained by using the two signals input from the input means in each direction, and the magnitude represented by the function of time and frequency from the two signals is cross-Wigner analysis calculation (JAES 31 Vol. 4 (1983) Year) (JAES, VO
Published in L.31, No.4 (1983). ), An analysis and operation means for performing an operation of integrating the result in the time direction, and a display means for displaying the result three-dimensionally in time, frequency and size for each direction.

The present invention can analyze and display the transient response characteristics of the power for each three-dimensional component from each of the two acoustic signals with the above-described configuration, and based on the result, the difference in the sound quality of the acoustic device is set as a physical value. It is possible to capture and analyze the direction of the signal source.

Example An acoustic evaluation apparatus according to an example of the present invention will be described below with reference to the drawings.

FIG. 1 shows a block diagram of a sound quality evaluation apparatus of the present invention.

1 is an input unit, 1a is a microphone, 1b is an A / D converter, 2
Is an analysis calculation unit, 2a is a cross-Wigner distribution calculation unit, 2b
Is an integration calculation unit, 3 is a display unit, and 4 is a vector display unit.

FIG. 2 shows the position of the microphone 1a of the input section 1 of the sound quality evaluation apparatus of the present invention on the XY plane. FIG. 3 shows the position of the microphone 1a of the input section 1 of the sound quality evaluation apparatus of the present invention on the YZ plane.

10 is the same as that used in the conventional example, and 11
Is a listening point, 12a and 12b are positions of microphones for capturing an impulse response which is an input for analyzing the X component of the signal at the listening point 11, 13a and 13b are positions of microphones for analyzing the Y component, 14a and 14b are microphone positions for analyzing the Z component.

An embodiment of the sound quality evaluation apparatus configured as above will be described.

Two points at the same distance on both sides of the listening point 11 on the three axes of the axis (Y axis) connecting the speaker 10 and the listening point 11 with the microphone 1a and the axes (X and Z axes) orthogonal to the axis ((12a, 12b),
The impulse responses in (13a, 13b) and (14a, 14b)) are captured by the input unit 1 and converted into digital signals by the A / D converter 1b. Next, in the analysis / calculation unit 2, the positions (12a, 12b), (13a, 13b), (14a, 14a,
Analytical calculation is performed by inputting the three sets of impulse responses in 14b). The cross-Wigner distribution calculation unit 2a calculates the cross-Wigner distribution from the impulse responses of the two points 12a and 12b on the X-axis, and the result is calculated by the integration calculation unit 2b as follows. Time t1 to t2 when the cross-Wigner distribution is calculated
Between the times t1 + n × Δt and t2 at any interval Δt, the X component of the cumulative power at the time t1 + n × Δt is calculated for all frequencies and times to calculate the X component of the cumulative power distribution. obtain. Similarly, the Y component of the cumulative power distribution is obtained from the impulse responses at the 13a and 13b2 points on the Y axis, and the Z component of the cumulative power distribution is obtained from the impulse responses at the 14a and 14b2 points on the Z axis.
Find the components as a function of time and frequency. Analysis calculation unit 2
Output on the display unit 3 in the X-axis direction,
Time is plotted in the Y-axis direction, and the logarithm of power is plotted in the Z-axis direction for display. 4 (a), (b) and (c) show the display results by the display unit 3 of the sound quality evaluation apparatus. In the sixth method, the direction component of the signal that could not be analyzed can be obtained as a function of time and frequency, and it becomes possible to objectively evaluate the sound quality difference for each direction component. Further, the vector display unit 4 adds up the calculation results of the analysis calculation unit 2 on the X, Y, and Z axes, respectively, and displays them as a vector indicating the signal source direction at the listening point 11. FIG. 5 shows a display result of the vector display unit 4. As a result, the direction component of the signal can be more finely and visually compared with the result of the display unit 3 and the signal source can be analyzed as a point, so that the audio device can be improved more appropriately.

Although the three-dimensional display is used as the display means, the size may be displayed in a two-dimensional contour map, and the display in which the correspondence with the time, frequency and size axes can be easily evaluated may be selected. . Further, as the vector display means, the direction of the signal at the listening point may be displayed two-dimensionally, or may be displayed centering on the signal source.

As described above, according to the present invention, in order to search the cause of the difference in the sound quality, the signals input with the respective direction components of the transient response characteristics of the power expressing the difference in the sound quality in the sense of hearing by the analysis calculation unit and the display unit. In addition, a sound quality evaluation device that enables analysis and display for each time and frequency is realized.

[Brief description of drawings]

FIG. 1 is a block diagram of a sound quality evaluation apparatus according to an embodiment of the present invention, and FIG. 2 is an explanatory view showing a position of a microphone of an input section of an acoustic evaluation apparatus according to an embodiment of the present invention on an XY plane. FIG. 4 is an explanatory view showing the position of the microphone of the input section of the sound quality evaluation apparatus of one embodiment of the present invention on the YZ plane, FIG. 4 is an explanatory view showing the output result of the sound quality evaluation apparatus display section of the speaker, and FIG. Is an explanatory diagram showing an output result of a speaker sound quality evaluation device vector display unit, and FIG. 6 is an explanatory diagram showing a cumulative power distribution of a speaker of a conventional example. 1 ... input section, 2 ... analysis calculation section, 3 ... display section, 4 ...
… Vector display, 10 …… speaker, 11 …… listening point.

Claims (2)

[Claims] 1. An input for obtaining an acoustic signal using a microphone at two places separated by a constant distance in each of three directions, a straight direction connecting a signal source and a listening point and two directions orthogonal to each other. Means and a cross-Wigner distribution calculation for obtaining a magnitude represented by a function of time and frequency from two signals input from the input means for each direction, and a cross-Wigner distribution calculation result for each frequency with a certain time as a base point. An analysis calculation means for performing integration calculation for performing integration while increasing or decreasing the time width ΔT, and a result of the analysis calculation means is divided into three values of time, frequency and size for each direction.
A sound quality evaluation apparatus comprising: a display unit for displaying a dimension. 2. The sound quality evaluation according to claim 1, further comprising vector display means for vector-adding the outputs of the analysis operation means in the two or three directions and displaying the direction vector of the signal for each time and frequency at the listening point or the signal source. apparatus.