What is the x axis and y axis if i plot(y) that y = audioread(​'filename.​wav') ?

I have to make equilizer as my project

So i read wav file by audioread

And i have to adjust x axis as frequency and y asix as sound pressure(db is right but it is hard to make to me)

for equilizer project.

But i don't know about axises.

I heared that y axis of plot(y) is sound pressure is it right?

And what is x axis?

help me

Thank you

Answer 1

[Star Strider]

The output of audioread for floating-point data is normalised to be between -1 and +1. Unless you have additional information about the mapping of the original data to the -1<=y<=+1 you will not be able to recover the original units.

You have to create your own x-axis (actually, time). Do that using Fs (the sampling frequency) as:

t = linspace(0, 1, size(y,1))'/Fs;

Remember that ‘y’ is a (Nx2) matrix (two channels, left channel is ‘y(:,1)’, right channel is ‘y(:,2)’).

[HS Kim]

Thanks really helpful!

[Star Strider]

My pleasure!

Answer 2

[Jan]

y = audioread('filename.wav');
plot(y)

Now the X-axis is the sample index. You need at least the sampling frequency to get real time:

[y, fs] = audioread('filename.wav');
t = (0:length(y)) / fs;
plot(t, y);

The values of y are the signal as values between -1 and +1.

Perhaps this helps: https://www.mathworks.com/matlabcentral/fileexchange/35876-sound-pressure-level-calculator