How to play a variation of frequency?

Hi,

1)Starting from a pure wave of a given frequency (4000 Hz) I can not implement this pseudo code to play a sound (pure wave) whose frequency decreases continuously from 4000 to 200:

demo matlab

   t = (0:0.001:100)';

for n = 4000:-1:200

     y = sin(2*pi*n*t)

     sound(y,Fs);

end

How to implement this correctly?

2)same question but starting from an very short audio file or an sound sample

thanks

[Walter Roberson]

Your code looks like it will work, but simply take a fair time ss it plays the sound about 3800 times.

[jérôme TAÏEB]

corrected script:

t=0:0.001:100;

for n=200:1:4000

     y=sin(2*pi*n*t);

     sound(y,n);

end

Now:

How to create in format.wav the obtained result by adding and scripting ?

thanks

[Walter Roberson]

That code changes frequency in two different ways simultaneously. You should not do that. Either change the n used in the construction of y or else change the frequency used for playback, but do not do both.

Hint: changing the n used in the construction of y is much easier to put together into a single .wav file than if you change the playback frequency.