Change Pitch
- Accessed by:
Change Pitch works by applying an up or down percentage change to the existing pitch of a selection. As well as choosing the percent change directly you can define it as:
- a change from one pitch to another
- a change in semitones
- a change from one frequency to another.
Change Pitch senses the first detectable pitch in a selection and sets "Pitch from" and "Frequency (Hz) from" accordingly. These two controls are not a detection of the "key" or "tonality" of music.
Pitch
If you know both the key the original recording is in and the key you want to change it to, change both the Pitch "from" and "to" values.
Note that whether Pitch "to" goes to the selected note above the "from" pitch or to the selected note below the "from" pitch depends on on the algorithm, so you need to check that the direction of the "Semitones (half-steps)" box underneath Pitch "to" is going down (minus sign) or up (no sign) as you intend. You can change the semitones value instead if you need to change pitch in the other direction (see the example below).
- Semitones (half-steps): If you don't know the key the original recording is in but you know how many semitones it needs to be changed, enter that value here. For example you could duplicate a vocal track and then apply Change Pitch with a value of +7 semitones (a major fifth) to create a harmony vocal.
We want the key to be the C# above, instead of A. In this case, choosing "C#/Db in Pitch "to" goes to the C#/Db below, but C# is four semitones above A, so we change Semitones (half-steps) to 4 and then the interdependent Percent Change box changes from -37.004 to the required 25.992.
Steve 21Aug13: Attempt to update the example:
In this case we can set the "from" pitch to be an A and the "to" pitch to be the C#/Db above the A. Note that the octave number changes between the notes B and C, so we will want to select C#/Db with an octave number one higher than the A. For example, if the detected note is A4 then the "from" note will show A and 4, so we need to set the "to" note as C#.Db and 5 (C#5/Db5).
Even if the detected note is not an A, to change the key from A to the C#/Db above we can manually enter an A as the "from" note and enter the C#/Db above as the "to" note, because it is the musical interval that is important. In this case the musical interval from A to C# above is 4 semitones, and we can check that setting in the "Semitones (half steps)" control.
We could also achieve an identical result by simply setting the "Semitones (half steps)" to 4.00, or setting the "Percent Change" to 25.992 (if we happened to know that 4 semitones is equivalent to 25.992%).
Frequency (Hz)
The "from" input box initializes to the first detectable pitch in the selection and does not update if the other controls are changed. However if you know the original frequency and the frequency you want to change to, you can enter these in the "from" and "to" boxes. Detection of a steady sine tone will be quite accurate in which case you may only need to change the "to" input box to the desired frequency for the tone.
- Percent Change: If you would like to change the pitch by a given percent, enter a value in this input box or use the slider.
Limitations
Change Pitch is a time-stretching effect, because it defies the normal expectation that to lower the pitch of the audio it is necessary to reduce its speed (and thus its length) and vice-versa. As with any time-stretching effect, some audible distortions will be expected at more extreme settings.
Due to weaknesses in its algorithm, Change Pitch does not keep the length exactly as before. This makes Change Pitch unsuitable for changing the pitch of individual very short notes. To avoid this problem, you can use instead, setting initial and final pitch change to the same amount.
