JPS6020128A - Indoor reverberation time measuring method - Google Patents

Abstract

PURPOSE:To select automatically a time interval, and to execute exactly a measurement by executing sampling by a sampling period until reaching a reference value of a sound pressure level from a time point of stop of a testing sound, and calculating a reverberation time. CONSTITUTION:A sampling time interval DELTAt and the number of inputs B of sampling data are determined by a pre-measurement. The inside of a room 1 is set to a diffusion sound field by driving a loudspeaker 2, in a state that band pass filters 5, 7 remain set to a frequency band selected by the pre-measurement, and subsequently, the loudspeaker 2 is turned off. After that time point, sampling data from an A/D converting circuit 10 is inputted by DELTAt and B until a measured sound pressure of a microphone 3 becomes a reference value (Lu+alpha+sigma). Such a data input is executed by a prescribed number of times, and a reverberation time of the inside of the room 1 is calculated.

Description

[Detailed description of the invention] The present invention relates to a method for measuring the remaining time in a room.

[Technical background of the invention] Conventionally, methods for measuring reverberation time in a room include white noise,
After firing a pistol sound etc. into the room, it is stopped, and after this stop point, the electric signal taken out from the micro bomb installed in the room is logarithmically converted, and the reverberant sound is recorded on the recording paper of a high-speed level recorder. Record the attenuation waveform,
The method used was to determine the reverberation time in the room from the slope of the recorded attenuation waveform. However, if you use this method,
Since humans read the slope from the attenuation waveform on the recording paper, there was a problem with the reliability of the measurement results, and it also required a huge amount of labor and time.

For this reason, recently, an electric signal (analog signal) from a microbon that receives reverberant sound is converted into a digital signal at a fixed sampling interval using an A/D converter. +process 1
, 1 by 1, simplification of 4111 between 111 and 4111 constant for residual ν, and shortening of measurement between 11.1 and 1 are often seen as (, 1, or -).

[Problems with the Background Art] As described above, in the method using the electric signal 13 from the microphone which received the reverberant sound and converting it into a digital signal, In many cases, 11,1 question is determined from the beginning.As shown in Figure '1, the remaining yy ni interval is 114. If λ・1 is short on the 41vi end, then the number of limp link data imported will be extremely reduced. Also, as shown in Figure 2, the reverberation time is taken into
If it is longer than r'b, only the leanbring data of the 9th ri part of the attenuation is JI calculation! Is it to take it inside?
＋、It is difficult to get the interval 4 easily、3 Furthermore, depending on the reverberation time J If the bling time interval is constant, the number of data stripped n,
It can be seen that the number of limbling data increases in proportion to the C1 capture roller of t lji+ , 'interval between limbling 111'. Therefore, if the reverberation time is very long, the number of rimbling data will be enormous, which will take up a lot of intercostal space for the performance, which will hinder high-speed processing. Just because there are many numbers does not mean that the accuracy will improve accordingly.

[Objective of the Invention 1] Therefore, the present invention has been made to solve the above-mentioned problems. According to the length of the reverberation time, !'Reverberation 11 based on rimbling data that is not affected by Jγ1
The purpose of this invention is to provide a method for measuring indoor reverberation time that can accurately measure the reverberation time within one room.

[Summary of the invention] Since the attenuation waveform of reverberant sound is created by combining the energy of diffuse sound and lIn noise 7-'4, the attenuation waveform attenuates to a noise level close to 1.1. The level of the spread r°~ is significantly affected by the background noise, and the level of the measured spread j1 (which is significantly different from the blind attenuation waveform) is higher than the level of the background noise? The colder the time, +17.1 t
! i! ? The error between '4's γtEF signal and the hull level of the reverberant sound becomes smaller, and this l? i; C], the accuracy of the measuring instrument is 40 and h is finally ignored (111 What? JI71 defeat with small error and negligible value?
Minimum of 1? ]'If the difference between the i pressure level and the ++g noise sound pressure level is expressed as α<13, then the sound pressure level of the diffused sound is lli'
j 4N 'r't (D?: i fL L/ he/
L/J, S+li fixed 1! Q Ta IJ' B < L
/ - (JJ, and after the diffused sound started to decay (
Highly reliable data is the f-event within the time period until the background noise level reaches -Iα) dB).

The present invention has been made based on the following findings.The average value of the background noise in the room and the standard deviation of From the sound source installed in the room based on the vote piece-deviation/l'10
4. At the end of the measurement related to the sound? 4 pressure level valve
Determine the l value, radiate a pre-measurement test sound from the sound source into the room to make the room a diffused sound field, stop the h IIJl of the $ pre-measurement test 71 at 11 degrees, and install C1 in the room. Measure the time it takes for the measured sound level to reach the base Q+- value from the time of the stop to the signal from the micro-bon that has been set, and thus calculate the level of the micro-bon on the basis of the intercostal space. Corresponding to the above-mentioned time or one digitizing period, a test sound for the main measurement is emitted from the sound source into the room to make the room a diffused sound field, and the test for the main measurement is performed. The generation of sound is stopped, and the signal from the microphone 11 is zumbling using the rimbling factor until the measured sound pressure level reaches Q'j lIfj from the time of stopping, and the zumbling data obtained in this way is Based on the above, the remainder of the room W 11
This is a method for measuring reverberation time in a room where an oil pipe runs between 7 rooms.

[Embodiment of the Invention] Fig. 3 is a diagram showing one embodiment of a neck for measuring indoor reverberation 111 for carrying out the present invention. 2 is the Subino J installed in room 1, 3 is the microphone installed in room 1, 4 is the noise generator (white signature sound light cow!::), ri is the noise generator Behind the output signal from 4'+E
U II < 1 of the lζ frequency band. ', Pass through Qi (transmission) -\1! Hunt pass filter 6 amplifies the signal from pass filter 5 to pass filter 1 and drives speaker 2.
] Large width 2;
5i, l, I'i! Rir.

71.1 Pandobus noise filter 5 stud band pass filter ccJ, this is the microphone 11 phon 3 output 1
Pass through the f8 bow of the selected frequency band behind the irises (
Denjsu) Shout. Hasid Passf (1 Furumasa (, 11, effective 111i (RMS) from Louis 17) is input to circuit 8 (, zoko (-C's effective value is detected, followed by this effective value circuit B h") logarithmic conversion circuit It is input to 9, and there it is changed to 1Ω, and then - (A / 1 (that 1)
]G/Digital) sol,, p/, human input to circuit '10 (, zoko C predetermined link 115 interval 1'?,'f
(Changed to jshital transmission, then (2f))△
1) Change 1φ circuit'I (,) /J eye interface 1 do /l shi (;i mouth (some '12 human power TL
ri),, 131J Inc. 1-1i;
1. There is a display means C for displaying the pre-warning result between the valves 1 and 12.

The bandpass filter 5.7 is controlled by the filter 12 via the interface 11, and its frequency band is selected. In the Δ/D conversion circuit '10 ()
The tatami numbering time interval is controlled by the bullet bomber 12.

With the above configuration, the reverberation time in the room 1 of the sea urchin C1 is measured. The work flow is shown in Figure 4 as a reference. First, the frequency band of the bandpass filter 5.7 is set to a predetermined frequency band by I n I>i12 (19 pre-', pa selection 'C' iJ3
and pre-measure the background noise in the room 1 for the selected frequency band. In other words, the speaker 2 is driven 1. !
Then, the signal from the microphone 3 is passed through the pan 1 to the pass filter 5, the effective value circuit 8, and the logarithmic conversion circuit 9, and then is A/D converted by the A/D conversion circuit 10 at predetermined rimbling time intervals.
[) Conversion. From the digital signals obtained, J calculates the background noise calculation LuJ3 and , it's no good that it's constantly changing,
Before) throat diffusion 7] 7 and this li'Hj noise;
gu α (1 bite? (11 ``1 J to harvest from the fruit, it's for sea urchins + l r し(, 111 C'K Il!! 12 k
J: 5 E(-, F4'-IEI Direct(ill'l
definite final +'II-'+ +:, -'s j'
-u4 (person'-1σ).

-) In the second light L"l ';'j, the speaker 26A as a source, -shi, and the microphone 3 in Figure 13.
J, Ru measurement Changzuki Ti l country of birth (as shown)
From power 2/i! <04, -shi: 1'+ii
I! Ill Sadagawa σ) trial i'1 microphone [-1 small 3 I
l(y) <j f3. Up, Rashi'10 (10 [,
1. Do the output of 6 +'i::'AI Di) to the number of people who are dying! , 21 Kaku, Subinono 2 Roichino Ifu, and Ano! , 211. 'From time -10,'
I'm going to ll嘱11jl+12 △/]) Weird] Gu! circuit 1
The distance between the rings 1111 and 0 is as follows: Counter circumference 1s1/l 1. y 7' and Karan 1-! lri shi, -same 1111 (11°1 ji 11
1o) △y'' i) From the conversion circuit 10 to the phosphor ring J-Y ('J 1.r I+'), the attenuation 11°1 level that falls within the constriction 1> (=41ζ-n) How many'
Import into 12. In 51 i'A i 2, the imported link/"-Tado 11゛, front 8111
(1,,
u 1 α (-rz) (dl' 3) Which comparison is the same 11° tj not in η mi 1 (J sound L [level is (lu-
At the time when the time becomes the same as +(λ σ), the acquisition of the rimbling data from the D conversion circuit 10 is completed. Counted BQNc (i.e., To to 1'
Uth fil of nmaC is equal), the main measurement ++'I
According to the length of the reverberation 111 of J3 ruru, △/'D variable recovery transformation 0, the lJ rimbling time interval is given by the following formula 1〉, (
2) In the formula, J = S61 (; Mugi 12 smell (determined). Also, one time a1! 1 constant, il style + 12 to Δ7・
The number 13 of the ring ring gates in the D-change 1 helmet circuit 10 is determined by the above (3).

tvl= ((Nc-'l)/2) Ii-(i
) [(Nc 1・) /'2 G;I: 2 points and truncate C 2. Capable of importing for one measurement Ilibring data Raku's B person 1st shift 1): Importing Pi1 to number M: variable (1, 2, 3...)] /1T=fvl I A 1. a -- (2) [/l nirin ringu 1i'+ interval,! 11:a: Counter period] 1, '3 = N c / M... (3) [[
3 Due to the import of Nilinbling data (rounding down to the decimal point)] 11) (2>Formula is, when Nc≦2, tvl = 1
Therefore, A I', = A t a and 4f.

In addition, in the case of M≧2b p, it can be seen that (M-1〉・2 gNc≦N11・2 Togi At =v −a'la. In this case, when 71t becomes popular, From equation 3), 2
≦13≦2b, and if b is E3, the data b-
4" (1r1 in the range of 128 to 256 is obtained as the number of intakes.

Through the above-described preliminary measurements, the interval 11 between the limping links 11 and the number 13 of limping data to be captured are determined. Next, Δ11 determined by preliminary measurement,
Perform this measurement for one frequency band using B.

First, with the band pass filter 5.7 set in the pre-selected frequency band 11111, the speaker 2 is driven to create a diffuse sound field within the entire area 1 as shown in Figure 3, and then to A], and from that point on, 7+
T-? I+;! 12, the Δ/D conversion circuit 1 converts At and B obtained in advance measurement until the measured sound pressure of the microphone 3 becomes base 1'; 111i (1-, u + α1σ).
The reverberation time in the room 1 is calculated based on the results obtained in this way.

The reverberation lf in room 1 for one frequency band is
Finish measuring for 1 and cover.

Then, as shown in Figure 4, we return to the frequency switching (selection) of the bandpass filter, and then move on to the pre-measurement of the frequency band we want to set, as described above, and then check the results of this pre-measurement. Perform the main measurement based on this. By automatically performing a series of operations in this way, it is possible to obtain appropriate limp ring data according to the length of the reverberation time for the reverberant waveform in any frequency band, and to avoid the influence of background noise. The remaining limp ring data in the room 1 is measured based on the limp ring data 17.

[Effects of the Invention] As explained above, according to the present invention, residual ? ! Automatically selects the sampling time interval according to the length of the old interval,
Furthermore, reverberation time can be measured extremely accurately based on lean-bring data that is not affected by background noise.

[Brief explanation of the drawing]

Figures 1, 2, 8-3, and 5 are diagrams showing the measured sound pressure characteristics of a blank space in the microphone, and Figure 3 is a diagram showing the reverberant intercostal measurements in a room for practical fM of the present invention. FIG. 4 is a flowchart showing an example of a more regular operation in the present invention. 1... Room 2... Speaker 3... Microphone 4... Noise Generator 5.7...Pan 1-pass noise filter d...Amplification support; 8...Executive value circuit 9
... Logarithmic conversion circuit 10...△, / [) Conversion circuit 12... Bow 1τ) (Iku application agent Patent attorney Kikuchi Part 5 / Cause Figure 2 Figure 3 Figure 5 Figure 4

Claims (1)

[Claims] Based on the average value and standard deviation of the background noise in the room, calculate the sound pressure level at the end of the measurement regarding the sound emitted from the sound source installed in the room. Expand the blank by emitting a test sound for
i sound field, and then stop emitting the test sound for pre-measurement, so that the sound pressure level is J when the test sound for pre-measurement stops.
: Measure the time from 1 to the reference value, and calculate the time from 11. above based on the time thus obtained. 1) Emit the test sound for the main measurement into the room from the recording source, make the room a diffused sound field, and then set the embedding period corresponding to the sample #I for the main measurement. stop the radiation of
The sound pressure level is the stop of the test sound for main measurement +L It;'i
A method for measuring reverberation time in a room, characterized in that the reverberation time in the room is calculated based on the 1T3 rimbling data obtained by sampling at the rimbling period from a point to the reference value.