JPS6217176B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a recording device for reverberation time frequency characteristics.

SUMMARY OF THE INVENTION An object of the present invention is to provide a recording device for reverberation time-frequency characteristics that can easily record reverberation time-frequency characteristics on a recording paper of a recorder.

Conventionally, reverberation meters that indicate reverberation time, for example,
As shown in FIG. 1, there is an oscillator 1 that oscillates a vibration sound of a predetermined frequency at a predetermined time interval, a reverberation time detection unit 2 that outputs the reverberation time, a conversion unit 3 that converts the reverberation time into an electrical signal, and a conversion unit 3 that converts the reverberation time into an electrical signal. unit 3
a control unit 4 that controls the
It is made up of.

The reverberation time detection unit 2 includes an amplifier 9 that amplifies the output of the microphone 8, a rectifier circuit 10 that rectifies the output of the amplifier 9, a compressor 11 that logarithmically compresses the output of the rectifier circuit 10, and an output of the compressor 11 as a reference. Voltage 1
4, and a time difference detector 13, which is essentially an exclusive OR circuit, which detects the difference between the pulse time width of the output pulse of the comparator 12 and the time width of the oscillation period of the oscillator 1. It is configured.

The conversion unit 3 is connected to a reference power source 15, an integrator consisting of an operational amplifier 16, a resistor 18, and an integrating capacitor 17, and is connected between the input end of the integrator and the output end of the reference power source, and the time difference detection circuit 13. It is composed of a switch element 20 that is turned on by an output, and a switch element 19 that short-circuits the integrating capacitor 17.

The control unit 4 has a counter 23 that counts the number of tone burst oscillations of the oscillator 1, a hold time setter 24 consisting of a timer that receives the output of the counter 23, and inputs the output of the counter 23 and the output of the hold time setter 24. It is composed of an AND circuit 25.

On the other hand, the indicator unit 5 is composed of an amplifier 21 for amplifying the output of the integrator, and an indicator driven by the output of the amplifier 21.

Now, for example, oscillator 1 generates a 1KHz vibration sound as the second
A case where the pulse is output five times during the positive voltage period of the pulse shown in FIG. a will be explained. Note that T ₁ in Figure 2a represents the period of the pulse, and T ₂ represents the period of the positive voltage of the pulse, and the oscillator 1 generates 5 tone bursts of the same vibration frequency with the period T ₁ as shown in Figure 2b. oscillates twice.

The output of the oscillator 1 is amplified by an amplifier 6 to drive a speaker 7. The output sound from the speaker 7 and its reverberation are converted into electrical signals by the microphone 8. FIG. 3a again depicts the waveform of a one-tone burst output from the oscillator 1.

The output of the microphone 8 is amplified by an amplifier 9, resulting in a waveform shown in FIG. 3b. Point P in Figure 3b is 1
This is the end point of the tone burst, and the waveform after point P is due to reverberation.

The output of the amplifier 9 shown in FIG.
The output waveform of the rectifier circuit 10 becomes an envelope of the waveform shown in FIG. 3b, as shown in FIG. 3c. The waveform corresponding to the reverberation part in FIG. 3c is a decaying waveform expressed by an exponential function.

The output of the rectifier circuit 10 is then logarithmically compressed by the compressor 11, and the attenuated waveform portion corresponding to the reverberation portion shown in FIG. 3c becomes a straight line, resulting in the waveform shown in FIG. 3d. 3d, which is input to the comparator 12.
The amplitude of the pulse waveform is a constant value E ₀ , and this value E ₀ is set in advance by the amplitude of the output of the oscillator 1 and the amplification factor of the amplifier 9 . Here, the value of the reference voltage 14 of the comparator 12 is set to a value of -20 dB of the _E0 . Therefore, the output waveform of the compressor 11 shown in FIG. 3d is compared with the reference voltage 14 by the comparator 12, and the pulse width T ₃ shown in FIG. A rectangular pulse shown in e is output.

The output pulse width T ₃ of the comparator 12 in FIG.
The time difference detection circuit 13 detects the difference between the oscillation period of the tone burst of the oscillator 1 shown in FIG. 3f, that is, the pulse width T ₂ of the rectangular wave, and
A rectangular wave with a pulse width T ₄ =T ₃ −T ₂ is output from the time difference detection circuit 13 as shown in FIG. This pulse width
T ₃ corresponds to the time until the reverberation reaches -20 dB, and three times the time of this pulse width T ₄ can be regarded as exactly the reverberation time.

During the period of pulse width _T4 , the switch element 20 is in an on state, the reference power source 15 is input to the integrator, and the output of the reference power source 15 is integrated for the period of time _T4 .

In the case of this example, since tone bursts are output five times as shown in FIG.
1 and is indicated to the indicator 22 as the reverberation time.

As mentioned above, time T ₄ corresponds to 1/3 of the reverberation time,
One measurement ends with five tone bursts, so
The scale is calibrated so that the indicator displays a reverberation time of 3T ₄ by integrating the integrator five times. Therefore, the average value of the reverberation times of five tone bursts is specified as the reverberation time.

Next, the number of tone bursts of the oscillator 1 is counted by a counter 23, and when the 5 tone burst ends, the counter 23 generates an output pulse, a hold time setting device, that is, a timer 24 is driven, and an AND circuit 25 of the oscillator 1 is counted. After the completion of the 5 tone burst, the hold setting device 24 generates an output as the time set by the hold time setting device elapses, turning on the switch element 19 and short-circuiting the integrating capacitor 17. Therefore, the indication of the indicator is held until the time set by the hold setting device elapses, and the output of the integrator becomes zero as the set time elapses, and then the hold time setting device is reset by the next measurement start signal and starts the next measurement. Prepare for measurement.

Now, in order to obtain the reverberation time frequency characteristics, for example, take the frequency characteristics at 1 octave intervals, and set the oscillation frequency of oscillator 1 to 62.5Hz, 125Hz, ...8KHz,
The reverberation time was measured for the earthquake sound whose center frequency was changed sequentially to 16KHz, and the reverberation time was recorded at frequency intervals of 1 octave by narrowing the center frequency to obtain the reverberation time frequency characteristics. was. For example, if the center frequency is 1 KHz, the oscillator 1 generates a 1 KHz vibration sound, the reverberation time is measured, and the measured reverberation time is recorded between 715 Hz and 1.43 KHz. This recording work had to be done manually and had the disadvantage of being time-consuming.

Therefore, the present invention records the output of the integrator by inputting it into a pen recorder, and also measures the length of the recording paper corresponding to a predetermined octave interval from the end of a predetermined number of tone burst oscillations of the vibration oscillator 1. It is configured to be driven only during sending time.

FIG. 4 is a block diagram of a reverberation time frequency characteristic recording apparatus according to an embodiment of the present invention.

In FIG. 4, the same components as those of the reverberation meter in FIG. 1 are given the same reference numerals.

The reverberation time frequency characteristic recording device shown in FIG. 4 includes an oscillator 1, a reverberation time unit 2, and a conversion unit 3.
, a control unit 4, a recorder 26 and a timer 28.

The oscillator 1, reverberation time unit 2, conversion unit 3, and control unit 4 have the same construction as the reverberation meter shown in FIG.

A recorder 26 receives the output of the integrator and records the reverberation time. On the other hand, the timer 28 is
The output of the timer 28 is configured to rotate a motor 27 that drives the recording paper of the recorder 26, and the set time of the timer 28 is such that the recording paper has a length corresponding to a frequency interval of a predetermined octave. It is set at the time it will be sent. Note that the frequency scale of the recording paper is graduated on a logarithmic scale.

First, in the reverberation time frequency characteristic recording device shown in FIG. 4, the measurement of reverberation time is the same as that of the reverberation meter shown in FIG. 1, so a detailed explanation thereof will be omitted.

For example, a tone burst of a predetermined frequency is oscillated five times, and the reverberation time is converted into a voltage and output from the integrator. The output of this integrator is input to the recorder 26, and the recording pen is swung to a position corresponding to the reverberation time. Next, when the oscillation of the fifth tone burst ends, the counter 23 outputs an output, the timer 28 is turned on until the set time elapses, and the drive motor drives the recording paper for the set time. For example, as in the example above, 62.5Hz125Hz...8KHz,
When drawing frequency characteristics at 1-octave intervals with 16KHz as the center frequency, first set the recording pen to be at a frequency of 48.5Hz, oscillate a 62.5Hz vibration sound with oscillator 1, and then complete the reverberation measurement. For example, the position of the recording pen indicating the reverberation time remains the same as the position corresponding to the reverberation time, and only the recording paper changes from 48.5Hz.
Moves the length corresponding to one octave up to 96.8Hz. The operation proceeds in the same manner at the next center frequency of 125 Hz. For example, at a center frequency of 1KHz, the recording paper is fed from 715Hz to a scale position of 1.43KHz. Similarly, the center frequency
Performs up to 16KHz. Therefore, there is 1 on the recording paper.
The reverberation time-frequency characteristics are plotted in a stepped histogram at octave frequency intervals.

Although the case where the tone burst is oscillated five times at the same center frequency has been described above, the number of tone bursts does not need to be limited to five, and may be set to any number of times from one to more. In this case, depending on the number of tone bursts, the reference power source 15 and the resistor 18
Alternatively, the value of the integrating capacitor 17 will be set corresponding to a preset number of times. The same applies to the counter 23.

Further, although the frequency interval of the reverberation time frequency characteristic has been described as one octave, it is not limited to one octave, and other intervals such as 1/3 octave or 1/2 octave interval may be used.
In this case, timer 2
8 will be determined.

As explained above, in the measurement of reverberation time, according to the present invention, the recording paper of the recorder is Since the reverberation time corresponding to each vibration sound frequency is driven, the reverberation time corresponding to each vibration sound frequency is recorded on the recording paper, and the reverberation time frequency characteristics can be easily recorded.

In addition, in the above explanation, the case where the recording paper drive motor is directly rotated for a predetermined period of time to drive the recording paper was explained, but instead of directly driving the motor, the recording paper driving motor is constantly rotated and the recording paper is A clutch or the like is interposed between the paper drive mechanism and the recording paper drive motor, and the clutch is operated for a predetermined period of time.
The same is true even if it is activated.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of a conventional reverberation meter. FIGS. 2a and 2b are explanatory diagrams showing the output cycle of an oscillator. FIGS. 3a, b, c, d, e, f, and g are waveform diagrams for explaining the action of the reverberation meter shown in FIG. 1. FIG. 4 is a block diagram showing the configuration of a reverberation time frequency characteristic recording apparatus according to an embodiment of the present invention. 1... Oscillator, 2... Reverberation time detection unit, 3...
Conversion unit, 4... Control unit, 9... Amplifier,
10... Rectifier circuit, 11... Compressor, 12... Comparator,
13... Time difference detection circuit, 14... Reference voltage, 15...
Reference power supply, 16... operational amplifier, 19 and 20...
Switch element, 23...Counter, 24...Hold time setter, 26...Recorder, 27...Recording paper drive motor, 28...Timer.

Claims (1)

[Claims] 1. An oscillator that oscillates vibration sounds of a plurality of predetermined frequencies a predetermined number of times at least once in a predetermined period, and a reverberation time using the output of this oscillator as input sound reproduced by a speaker and reverberation sound. a reverberation time detection means for detecting the reverberation time; a conversion means for converting the output of the reverberation time detection means into an electrical signal; a control means having a counter for counting the number of oscillations of the oscillator; and a recorder whose recording state is controlled by a control means, the recorder having a frequency logarithmic scale on the horizontal axis and a time linear scale on the vertical axis. The recording paper is configured to record the reverberation time using the output of the converting means as an input, and is equipped with a timer set to a time for feeding the recording paper by a length corresponding to a frequency interval of a predetermined octave. through which the counter output of the control means is supplied to the drive motor that feeds the recording paper; A reverberation time frequency recording device comprising: