About: Change Pitch


So I’ve been using audacity for about 7 years and am familiar with the Change Pitch effect. Now I am trying to use the From & To boxes but they don’t change it to the frequency I enter. I want to change from 2004.545 to 1975, but it won’t go. It even suggests a change to 1974.998 but then does not perform the change. Is this a bug? I don’t ever remember having a problem using the from & to boxes to effect precise pitch changes.

It works for me, though the change is small (less than 1.5%) so the effect is subtle.

After entering the numbers, check that the “Percent Change” says “-1.474”.

What exactly does it say?

I included the percentage of -1.474, as you suggest, but after applying this change again, it still reads From: 2004.545 To: 1974.998. It still rejects actually changing the pitch to 1974.998. The semitones box reads -0.26.

I don’t understand what problem you are trying to describe.

Perhaps the manual can explain: https://manual.audacityteam.org/man/change_pitch.html

I began with that link in the first post. I’m very familiar with the Change Pitch function, after 7 years of use. Something is not working properly. It’s not changing the pitch to the number that I select, nor the number that it suggests. It suggests 1974.998, but when I hit OK, It comes back unchanged. When I measure the pitch it is still unchanged. In short, the Change Pitch effect is not functioning.

I suspect the problem is that you are expecting too much accuracy from the effect’s estimate of the current pitch.

Human error. https://pages.mtu.edu/~suits/notefreqs.html
According to the chart I was consulting B6 is 1975. I read it incorrectly and was putting in 1750. I was 250 cents (5 semitones) off from the estimate of 2000 that Audacity was giving. It’s nice to know that the machines are now smarter than I am!

Something else about Change Pitch. I’m trying to alter the pitches of some very low notes. they should be in the range of around 100 hz. but the calculator (From box) is telling me in the 10’s of 1000’s. I’ve noticed this before but never mentioned it. It must be detecting only the overtones?

The pitch approximation is based on FFT analysis of the first 0.2 seconds of audio with a window size of 2048 samples. That can produce reasonable accuracy for pure sine tones down to about 100 Hz. Below 100 Hz it becomes increasingly inaccurate. As most natural sounds are a combination of multiple frequencies, the results will not always be as expected - it depends on which FFT bin has the highest peak.