# counting the number of frequency in wav file

조회 수: 15(최근 30일)
faiz hazizi 2018년 4월 24일
댓글: faiz hazizi 2018년 4월 29일
hi, i would like to count the number of frequency on my sample audio file. it is a recorded drum audio file which contain 8 beat of kick pedal in 7 seconds. so the problem is, how to make a simulation to count the number of kick pedal in this audio file (.wav)
here are my .wav file
t=linspace(0,length(y)/fs,length(y));
plot (t,y)
##### 댓글 수: 7표시숨기기 이전 댓글 수: 6
Jan 2018년 4월 26일
@faiz hazizi: Remember that a diagram without labels does not explain anything. What do the two diagram represent?
The original signal has positive and negative values. You are not interested in the maximum value, but in the maximum amplitude. This can be positive or negative. Using abs helps to move all values to the positive side. If you have a single signal (mono sound), this is exactly the same as RMS: The mean of a scalar is the scalar, and Root of Squared value makes the sign positive. For a stereo signal, RMS considers both channels.
There is no "relationship" between RMS and findpeaks. The first one converts the signal to do what you want, the second one finds the peaks.
"your_signal" is the "y" in your code: The variable in which the audio signal is stored.

댓글을 달려면 로그인하십시오.

### 채택된 답변

Jan 2018년 4월 26일
yRMS = sqrt(sum(y .^ 2, 2)); % Root mean square, same as abs(y) for mono signal
[pk, loc] = findpeaks(yRMS, 'MinPeakHeight', std(yRMS));
See doc findpeaks for more methods.
##### 댓글 수: 1표시숨기기 없음
faiz hazizi 2018년 4월 29일
thank you sir, appreciate that, i'll try run the program first. if there's is any in problem regarding to this program i'll ask again sir, thank you

댓글을 달려면 로그인하십시오.

### 추가 답변(1개)

Von Duesenberg 2018년 4월 25일
A possible workflow:
%compute the envelope of y (your signal)
%assuming it's mono, and adjust the second
%parameter of the envelope function with
%successive plots of myEnv
[myEnv, ~] = envelope(y, 3000, 'peak');
[pk, loc] = findpeaks(myEnv, 'MinPeakProminence', .5);
%get the number of peaks
nbPk = length(pk);
##### 댓글 수: 6표시숨기기 이전 댓글 수: 5
Jan 2018년 4월 26일
@faiz: "Mono" means, that the sound has been recorded with 1 channel. "Stereo" uses 2 channels, and needs 2 microphones. Ask WikiPedia for details.
If a sound is recorded with 2 channels, the output of audioread must have two columns also. See: doc audioread.

댓글을 달려면 로그인하십시오.

### 범주

Find more on Descriptive Statistics in Help Center and File Exchange

### Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by