JP2007271485A - Tone evaluation support method and tone evaluation support apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide information suitable for evaluation of timbre, in a method and device for supporting the timbre evaluation for providing the information suitable for the evaluation of the timbre of sound, such as noise. <P>SOLUTION: A sound signal, obtained by collecting sounds, is divided into a plurality of signal components of different tones, amplitude moderation frequency and amplitude modulation width of each of the plurality of signal components is determined, and the amplitude modulation widths of the signal components are displayed at corresponding coordinate points, with respect to the axes of the frequency of the signal components and amplitude moderation frequency of the signal components. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a timbre evaluation support method and a timbre evaluation support apparatus that provide information suitable for evaluation of the timbre of a sound such as noise.

  Conventionally, a sound level meter is known as an apparatus for evaluating the magnitude of noise. This sound level meter performs auditory correction that gives a greater weight to signal components of frequencies that can be heard as loud sounds by human ears. The sound pressure of the signal is displayed in dB or the like. In the case of this general sound level meter, if it is a signal component of the same frequency, it has the same weight regardless of the temporal fluctuation amount of the sound pressure level of the signal component. However, since the auditory characteristics change depending on the temporal fluctuation speed of the sound pressure level of the signal component, not only the frequency of the signal component but also the fluctuation speed of the sound pressure level of the signal component is included in the signal component of each frequency. It has been proposed to obtain an evaluation value by weighting in consideration (see Patent Documents 1 and 2). The frequency range in which humans can recognize the pitch of sound is generally said to be around 40 Hz to 20 kHz, and furthermore, the sound pressure level of signal components that humans feel audibly different, that is, can be recognized as a difference in timbre. The fluctuation speed is widely distributed from a relatively low frequency component (for example, 1 Hz) to a high frequency component (for example, 200 Hz).

According to the proposals in Patent Documents 1 and 2, since the weighting is performed in consideration of not only the frequency of the signal component but also the fluctuation speed of the sound pressure level of the signal component, the evaluation value is more suitable for human hearing. Is required.
Japanese Patent Laid-Open No. 3-82922 JP-A-6-117912

  However, according to the above proposal, although an evaluation value suitable for human hearing is required, it is not sufficient to pursue the cause of the evaluation. For example, it is unclear whether it is effective to suppress the sound pressure level itself or to suppress fluctuations in the sound pressure level in order to lower the evaluation value (lower the noise level).

  In view of the above circumstances, an object of the present invention is to provide a timbre evaluation support method and a timbre evaluation support apparatus that present information suitable for evaluation of a timbre of sound such as noise.

To achieve the above object, the timbre evaluation support method of the present invention comprises:
A sound collecting step for collecting a sound to be evaluated to obtain a sound signal;
A pitch separation step for separating the sound signal obtained in the sound collection step into a plurality of signal components having different pitches;
A modulation detection step for obtaining the amplitude modulation frequency and amplitude modulation width of the signal component for each of the plurality of signal components obtained in the pitch separation step;
A display step of taking the frequency of the signal component on one axis, taking the amplitude modulation frequency of the signal component on the other axis, and displaying the amplitude modulation width of the signal component at the corresponding coordinate point.

  According to the timbre evaluation support method of the present invention, the amplitude of the signal component and the amplitude modulation frequency of the signal component are used as axes, and the amplitude modulation width of the signal component is displayed at the corresponding coordinate point. It can be seen at a glance whether it fluctuates with frequency, and it is extremely effective in analyzing the sound to be evaluated.

  Here, in the timbre evaluation support method of the present invention, the timbre evaluation support method further includes an audibility correction step for correcting an audibility of the sound signal obtained in the sound collection step, and the pitch separation step is obtained in the sound collection step. It is preferable to separate the sound signal that has been subjected to auditory correction in the auditory correction step into a plurality of signal components having different pitches.

  By placing the auditory sensation correction step, a display for performing analysis suitable for human audibility is performed.

  In the timbre evaluation support method according to the present invention, it is preferable that the display step is a step of displaying the amplitude modulation width of the signal component in shades or colors according to the amplitude modulation width.

  By displaying the amplitude modulation width of the signal component with the shading or color according to the amplitude modulation width, the level of the amplitude modulation width can be known at a glance.

  It should be noted that when displaying the amplitude modulation width of the signal component, both of the shading and the color may be used together, or may be displayed three-dimensionally, for example, as a bar graph.

The timbre evaluation support device of the present invention that achieves the above-described object
A pitch separation unit that separates the sound signal into a plurality of signal components having different pitches;
For each of a plurality of signal components obtained by the pitch separation unit, a modulation detection unit for obtaining the amplitude modulation frequency and amplitude modulation width of the signal component;
A display unit that takes the frequency of the signal component on one axis, takes the amplitude modulation frequency of the signal component on the other axis, and displays the amplitude modulation width of the signal component at a corresponding coordinate point; To do.

  Here, the timbre evaluation support apparatus of the present invention also has an audibility correction unit that corrects the audibility of the sound signal, and the pitch separation unit includes a plurality of sound signals that are audibly corrected by the audibility correction unit. It is preferable that the signal component is separated.

  In the timbre evaluation support device according to the present invention, it is preferable that the display unit displays the amplitude modulation width of the signal component in shades or colors according to the amplitude modulation width.

  According to the present invention, information suitable for timbre evaluation is displayed in an easily recognizable form.

  Hereinafter, embodiments of the present invention will be described.

  FIG. 1 is a block diagram showing an embodiment of a timbre evaluation support apparatus of the present invention.

  The timbre evaluation support apparatus 10 shown in FIG. 1 includes a microphone 1, a loudness calculation unit 2, a frequency limit loudness detection unit 3, a plurality of amplitude modulation wave component detection units 4, a plurality of amplitude amount detection units 5, and a matrix display unit 6. Consists of. Sound generated from an automobile or industrial equipment is collected by the microphone 1 and converted into an electrical signal. The loudness calculation unit 2 adds an audible characteristic such as masking to the loudness as a physical quantity, and converts it into the loudness actually heard by a human, that is, the loudness amount. The frequency-limited loudness detection unit 3 divides a sound including various frequency components (sound pitch) into a plurality of loudness waveforms each having a certain width and different frequency bands using a frequency filter. It is. The loudness waveform divided into each frequency band is input to a plurality of amplitude modulation wave component detection units 4 that are responsible for each band of the modulation frequency.

  FIG. 2 is a diagram schematically showing one of a plurality of loudness waveforms obtained by division in the frequency-limited loudness detection unit 3.

  The loudness waveform obtained by the division in the frequency limit loudness detection unit 3 is, for example, a waveform as shown by a solid line in FIG. 2, and generally, amplitude modulation is periodically performed as shown by a broken line in FIG. Has been.

  Each of the plurality of amplitude-modulated wave component detection units 4 shown in FIG. 1 uses a fluctuation component extraction filter that takes charge of each frequency band when the frequency band of 1 Hz to 200 Hz, for example, is further divided into a plurality of frequency bands (in FIG. 2). A fluctuation frequency component (broken line in FIG. 2) that is an envelope of a solid line) is extracted.

  FIG. 3 is an explanatory diagram of the operation of the amplitude modulation wave component detection unit.

  FIG. 3A shows a loudness waveform which is schematically shown here but is shown by a solid line in FIG. 2, for example. Here, it is assumed that the amplitude periodically varies at a speed of 5 Hz.

  FIG. 3B shows the passband characteristics of each fluctuation component extraction filter employed in each of the plurality of amplitude modulation wave component detection units 4 (see FIG. 1). That is, here, each fluctuation component extraction filter is shown as a filter that extracts a frequency component having a certain width centering around 5 Hz, 10 Hz, 15 Hz, 20 Hz, 25 Hz,.

  When the loudness waveform in FIG. 3A is passed through the plurality of amplitude modulation wave component detection units, the waveform that has passed through the amplitude modulation wave component detection unit using the fluctuation component extraction filter having a center frequency of 5 Hz is shown in FIG. ), An envelope that changes at 5 Hz is extracted, and the amplitude-modulated wave component detection unit using a fluctuation component extraction filter with a center frequency other than 5 Hz, as shown in FIG. Remain unprinted.

  In the plurality of amplitude-modulated wave component detection units 4 shown in FIG. 1, the processing described with reference to FIG. 3 is performed for each loudness waveform for each frequency band obtained by the division in the frequency-limited loudness detection unit 3. .

  Each envelope waveform output from each of the plurality of amplitude modulation wave component detection units 4 is input to each of the plurality of amplitude amount detection units 5, and the amplitude of the envelope waveform input to each amplitude amount detection unit 5 The quantity (depth of the valleys; value d shown in FIGS. 2 and 3) is detected.

Further, the matrix display unit 6 displays the frequency (sound pitch: f _n ) and fluctuation frequency (fluctuation speed: F _n ) divided by the frequency limit loudness detection unit 3 and the amplitude modulation wave component detection unit 4 on two axes. The depths of the peaks and valleys of the envelope of the loudness waveform detected by the amplitude amount detection unit 5 are displayed in levels for each shade of color or color corresponding to each region.

  FIG. 4 is a diagram illustrating an example of a display form on the matrix display unit.

In FIG. 4, the horizontal axis represents the frequency f _{n of the} sound signal, and the vertical axis represents the fluctuation frequency F _n of the loudness waveform divided into each frequency band, and the amplitude of fluctuation (depth of the mountain valley; The indicated value d) is displayed in different shades or colors.

  As described above, according to this embodiment, since the feature quantities of various timbres can be expressed by a shade map or color map, it is possible to recognize a fluctuating sound component that has been audibly different but could not be quantified so far. It becomes like this. Therefore, more detailed timbre evaluation becomes possible, and technical improvement to sound quality design in various industrial fields, shortening of the development period, and cost reduction for development are achieved.

It is a block diagram which shows one Embodiment of the timbre evaluation assistance apparatus of this invention. It is the figure which showed typically one of the several loudness waveforms obtained by the division | segmentation in a frequency limited loudness detection part. It is explanatory drawing of an effect | action of an amplitude modulation wave component detection part. It is a figure which shows an example of the display form in a matrix display part.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Microphone 2 Loudness calculating part 3 Frequency-limited loudness detection part 4 Amplitude modulation wave component detection part 5 Amplitude amount detection part 6 Matrix display part 10 Tone evaluation assistance apparatus

Claims (6)

A sound collecting step for collecting a sound to be evaluated to obtain a sound signal;
A pitch separation step for separating the sound signal obtained in the sound collection step into a plurality of signal components having different pitches;
A modulation detection step for obtaining an amplitude modulation frequency and an amplitude modulation width of the signal component for each of the plurality of signal components obtained in the pitch separation step;
A display step of taking the frequency of the signal component on one axis, taking the amplitude modulation frequency of the signal component on the other axis, and displaying the amplitude modulation width of the signal component at a corresponding coordinate point. Tone evaluation support method to do. An auditory correction step of correcting the auditory sense of the sound signal obtained in the sound collection step;
The pitch separation step is a step of separating the sound signal obtained in the sound collection step and further subjected to auditory correction in the auditory correction step into a plurality of signal components having different pitches. Item 1. The timbre evaluation support method according to Item 1.   2. The timbre evaluation support method according to claim 1, wherein the display step is a step of displaying the amplitude modulation width of the signal component in a shade or color according to the amplitude modulation width. A pitch separation unit that separates the sound signal into a plurality of signal components having different pitches;
For each of the plurality of signal components obtained by the pitch separation unit, a modulation detection unit for obtaining the amplitude modulation frequency and amplitude modulation width of the signal component;
A display unit that takes the frequency of the signal component on one axis, takes the amplitude modulation frequency of the signal component on the other axis, and displays the amplitude modulation width of the signal component at a corresponding coordinate point; Tone evaluation support device. Equipped with an auditory correction unit that corrects the auditory sense of the sound signal,
5. The timbre evaluation support apparatus according to claim 4, wherein the pitch separation unit separates the sound signal subjected to the auditory correction by the auditory correction unit into a plurality of signal components having different pitches.   5. The timbre evaluation support apparatus according to claim 4, wherein the display unit displays the amplitude modulation width of the signal component in shades or colors according to the amplitude modulation width.

Images