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Thursday, 8 August 2013

How to measure the frequency (Hz value) of a single sine wave length in Audacity

I generated a 16 seconds long sine wave tone at 880 Hz in Audacity.
Then I applied a sliding time scale pitch shift to it, from start to finish, starting at 0 semitones and finishing at 12 semitones--effectively increasing the pitch over time by a whole octave (doubling its frequency in Hz, i.e. 1760 Hz).

But I wanted to double check the frequency of the very first wave length, to see if it was still 880 Hz.

First, I had to set Audacity's selection toolbar to show "samples".

Then I just put the cursor at the end of the first wavelength and saw that it was 50 samples long.

After that, you just use a formula I found on Audacity's Plot Spectrum page:
44100/2/(50/2)=882 Hz

44100 Hz is the (default) project rate and 50 is the number of samples in 1 wavelength.

So, yeah, it's pretty accurate for what I was expecting.

1 comment:

  1. do you know of a way to get Audacity to show the physical wavelength of a sound instead of the period?


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