用於 wav 文件頻譜密度分析的單位存在問題（db 人為低）

Question

我有以下代碼，它改編自我在這里找到的其他代碼。 它運行良好，plot 看起來和預期的一樣，除了 db 級別太低了 ~80db。 請注意，預期單位為 db re 1uPa。 非常感謝有關解決此問題的任何意見，我認為這與需要 re 1uPa 有關，但我無法追溯問題，我只是一個試圖學習編碼的可憐的生物學家！

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% FFT parameters
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
NFFT = 96000;    % 
NOVERLAP = round(0.75*NFFT);
w = hanning(NFFT);
% spectrogram dB scale
spectrogram_dB_scale = 100;  % dB range scale (means , the lowest displayed level is XX dB below the max level)
gain = 20
sensitivity = - 165
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% load signal
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
[data,Fs]=audioread('sample.wav'); %(newer matlab)
samples = length(data);
dt = 1/Fs;
t = (0:dt:(samples-1)*dt);
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% display 1 : averaged FFT spectrum
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
[sensor_spectrum, freq] = pwelch(data,w,NOVERLAP,NFFT,Fs);
% convert to dB scale (ref = 1)
sensor_spectrum_dB = 20*log10(sensor_spectrum) - sensitivity - gain ;


figure(1),semilogx(freq,sensor_spectrum_dB);grid
title(['Averaged FFT Spectrum  / Fs = ' num2str(Fs) ' Hz / Delta f = ' num2str(freq(2)-freq(1)) ' Hz ']);
xlabel('Frequency (Hz)');ylabel('Amplitude (dB (L))');

Answer 1

1. 無論如何，您想要使用10*log10的 plot 和 pwelch 的pwelch ，因為您正在處理功率譜。

2. 如果不了解更多關於您的數據的信息，將很難提供幫助……這是可靠的數據嗎？ 生理？ 什么是靈敏度單位？ 什么是gain ？？

3. 縮放 PSD