4楼: Originally posted by somomo91 at 2018-05-23 14:58:15
计算声压有很多方法，用FFT 也可以，或者用其他的 filter
通常，更好的是用  A-weighting
AWeighting = weightingFilter('A-weighting', 48000)
我现在没法用MATLAB测试，你可以先试试这个例子，用 butter fil ...

Pref=20; % 20microPascal
Y = fft(y)
db = 20*log10((abs(Y)/Pref))

2楼: Originally posted by somomo91 at 2018-05-23 02:19:50
正常是

Pref=20; % 20microPascal
Y = fft(y)
db = 20*log10((abs(Y)/Pref))

但有很多解释，比较啰嗦

或者你可以用最新的 MATLAB 2018A，语音处理工具箱 新添加了一个 splMeter ，专门量 spl 的，这个比 ...

3楼: Originally posted by 沉默18 at 2018-05-23 08:34:24
非常感谢您！Y=fft（y），Y不是是声压才可以用您下面那个分贝计算公式？您知道怎么才能得到声压吗？
...

AWeighting = weightingFilter('A-weighting', 48000)

[wav,fs_Hz]=audioread( "audiofile.wav");  %load the WAV file
my_cal_factor = 1.0;  %the value for your system to convert the WAV into Pascals
wav_Pa = wav * my_cal_factor;

%extract the envelope
smooth_sec = 0.125;  %"FAST" SPL is 1/8th of second.  "SLOW" is 1 second;
smooth_Hz = 1/smooth_sec;
[b,a]=butter(1,smooth_Hz/(fs_Hz/2),'low');  %design a Low-pass filter
wav_env_Pa = sqrt(filter(b,a,wav_Pa.^2));  %rectify, by squaring, and low-pass filter

%compute SPL
Pa_ref = 20e-6;  %reference pressure for SPL in Air
SPL_dB = 10.0*log10( (wav_env_Pa ./ Pa_ref).^2 ); % 10*log10 because signal is squared

%plot results
figure;
subplot(2,1,1);
t_sec = ([1:size(wav_Pa)]-1)/fs_Hz;
plot(t_sec,wav_Pa);
xlabel('Time (sec)');
ylabel('Pressure (Pa)');

subplot(2,1,2)
plot(t_sec,SPL_dB);
xlabel('Time (sec)');
ylabel('SPL (dB)');
yl=ylim;ylim(yl(2)+[-80 0]);