function A_weight_dB()

clear all;clc;

Audio_File='.\';

% 获取文件夹下的所有文件信息，并存入music结构体

music=dir([Audio_File '*.wav']);

Calculate(Audio_File,music);

end

function  Calculate(Audio_File,music)

for i=1:length(music)

[y,fs]=audioread(strcat(Audio_File,music(i).name));

Frame_Len=3000;                                       % 帧长

End_Frame=length(y)-Frame_Len;                        % 结束帧位置

Step_Len=Frame_Len;                                   % 步长

dBA=[];cnt=1;

for k=0:End_Frame/Step_Len

Frame=y(k*Step_Len+1:k*Step_Len+Frame_Len);

[~,dBA(cnt,1)] = estimateLevel2(Frame,fs,55);

cnt=cnt+1;

end

Mean_dBA=mean(dBA)

Max_dBA=max(dBA)

end

end

function [X,dBA] = estimateLevel2(x,Fs,C)

% 计算分贝

X = abs(fft(x));

XX=X;

f = (Fs/length(X))*[0:(length(X)-1)];

ind = find(f

f = f(ind);

X= X(ind);

indx=find(X>0);

X(X == 0) = 1e-17;

A = filterA(f);

min_X=min(X);

X=X*(1/min_X);

X = A'.*X;

X=X/(1/min_X);

if ~isempty(indx)

X=X(indx);

totalEnergy = sum(X.^2)/length(X);

meanEnergy = totalEnergy/((1/Fs)*length(X));

dBA = 10*log10(meanEnergy+1)+C;

if dBA<30

dBA=30;

end

X = 20*log10(X);

else

dBA=30;

X=XX;

end

end

function A = filterA(f,plotFilter)

c1 = 3.5041384e16;

c2 = 20.598997^2;

c3 = 107.65265^2;

c4 = 737.86223^2;

c5 = 12194.217^2;

% Evaluate A-weighting filter.

f(find(f == 0)) = 1e-17;

f = f.^2; num = c1*f.^4;

den = ((c2+f).^2) .* (c3+f) .* (c4+f) .* ((c5+f).^2);

A = num./den;

% Plot A-weighting filter (if enabled).

if exist('plotFilter') & plotFilter

% Plot using dB scale.

figure(2); clf;

semilogx(sqrt(f),10*log10(A));

title('A-weighting Filter');

xlabel('Frequency (Hz)');

ylabel('Magnitude (dB)');

xlim([10 100e3]); grid on;

ylim([-70 10]);

% Plot using linear scale.

figure(3); plot(sqrt(f),A);

title('A-weighting Filter');

xlabel('Frequency (Hz)');

ylabel('Amplitude');

xlim([0 44.1e3/2]); grid on;

end

end