Let's say the song is at 122 bpm. And i want to decrease it by 10% to approximately 110 bpm. How much do I need to increase/decrease the pitch now to get back the original pitch of the song?
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1Is there any particular reason you can't do this in a single step? Most DAWs can change tempo without altering pitch. – Tetsujin Apr 22 '20 at 09:57
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I'm very new to this. I don't know what a DAW is. Let's say I have a very basic app that only allows to me bump up/down the pitch and same for the tempo. So if i took the tempo to 90%. Would you have any idea how much i would need to adjust the pitch approximately? – Derpp Apr 22 '20 at 10:28
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DAW = Digital Audio Workstation. Even the most basic of freeware DAWs, Audacity, can do time-stretch - https://manual.audacityteam.org/man/change_tempo.html – Tetsujin Apr 22 '20 at 10:36
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Like Tetsujin wrote - any decent digital editor can change tempo and pitch independently. – Carl Witthoft Apr 22 '20 at 14:47
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@Tetsujin so if someone named "Jack" designs a workstation, it's a .. Jackdaw! – Carl Witthoft Apr 22 '20 at 14:48
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@Dave are you suggesting that the OP take that other answer and apply it 122-110 = 12 times? ;) – piiperi Reinstate Monica Apr 23 '20 at 04:56
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12 * log2(newtempo / oldtempo) = pitch difference in semitones caused by the tempo change.
For example, tempo change from 122 to 110 lowers the pitch by about 1.79 semitones:
12 * log2(110/122) = -1.79253148845872...
Another example, tempo change from 122 to 244:
12 * log2(244/122) = +12.0
i.e. exactly one octave.
BPM is a unit of frequency, the same physical quantity as "pitch", just 60 times bigger numbers. 120 bpm = 2 Hz, two beats per second. 110 bpm = 1.833 Hz.
To reverse the pitch change caused by the tempo change, pitch-shift it by the same amount in the other direction.
However, any sort of musical audio editor usually has a pitch-preserving tempo change, and tempo-preserving pitch change mode.
piiperi Reinstate Monica
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