How do I transpose keys in Audacity?

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serpentynePosts: 1Joined: Tue Dec 16, 2008 12:36 pmOperating System: Please select

How to change key of a song?

Hi - I'm a newbie here, so forgive me if I'm clueless about a lot of things. I want to change the key of an entire song from, say, F-key to D-key. How am I supposed to go about doing that?

stearman65Posts: 140Joined: Thu Sep 11, 2008 3:06 pmOperating System: Windows 10 / 11

Re: How to change key of a song?

Post by stearman65 » Tue Dec 16, 2008 1:08 pm

Hi
Hilight your song, click effect, scroll down to change pitch and select the key you want. You may have to juggle other settings after you change.
Stearman65

steveSite AdminPosts: 85549Joined: Sat Dec 01, 2007 11:43 amOperating System: Linux *buntu

Re: How to change key of a song?

Post by steve » Tue Dec 16, 2008 6:18 pm

You should be aware that the further you "de-tune" the song, the worse the sound quality will be.
If it doesn't matter about the tempo of the song, then the "Change Speed" effect gives better sound quality (but both tempo and pitch will change together - just like playing a record at the wrong speed).

Learn more about Nyquist programming at audionyq.com

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steveSite AdminPosts: 85549Joined: Sat Dec 01, 2007 11:43 amOperating System: Linux *buntu

Re: How do I change keys or transpose

Post by steve » Tue Mar 10, 2020 12:12 pm

If you wish to retain the original tempo, use the "Change Pitch" effect. Note that this effect will have an impact on the sound quality - the greater the pitch shift the greater the impact on sound quality. For best quality, try both with and without "Use high quality stretching (slow)" selected to see which sounds better (Usually it sounds better with that option selected, but not always - it depends on the source material). https://manual.audacityteam.org/man/change_pitch.html

Alternatively, if you don't mind the tempo changing, then the "Change Speed" effect may give better sound quality: https://manual.audacityteam.org/man/change_speed.html

Learn more about Nyquist programming at audionyq.com

Use Change Pitch to change the pitch of a selection without changing its tempo (speed).

To change pitch and tempo simultaneously, use .

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.

• Estimated Start Pitch: Attempts to detect the pitch of the most meaningful note at the start of the selection. The letter (with sharp "#" / flat "b" suffix as required) indicates the musical note and the number indicates the octave position of the note. The frequency of the detected pitch is given in parentheses. For example, if you have a very short, quiet note on A3 followed by a longer, louder note on C4 Audacity will probably detect C4 but if the second note is the same volume then Audacity will probably detect A3.
• "from" and "to" controls: The "from" and "to" controls each have a dropdown menu for selecting the musical note, then to right of that menu, a text box for selecting the octave of that note.
• Semitones (half-steps): If you do not 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.

If you change the Pitch "to" note when the "from" and to" octaves are the same, this could mean either an increase or decrease in pitch depending on the "from" Pitch. So it is recommended to check in the "Semitones (half-steps)" box if the value is going down (minus sign) or up (no sign) as you intend. If you need to change pitch in the other direction you can change the semitones value instead (see the example below) or change the "to" octave number.

Frequency (Hz)

The "from" input box initializes to the first meaningful detected 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 often be very accurate (with the upper frequency limitation noted below) 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.

Use high quality stretching (slow)

If this checkbox is enabled, the same SBSMS high quality algorithm is used that is used in the Sliding Stretch effect. Change Pitch will process much more slowly if this checkbox is enabled, but the exact length of the selection will be preserved. For small to moderate tempo changes, the resulting quality will usually be higher, especially with percussive music (such as piano music).

Example

Change the known key from A to the C#/Db above that A

If we have music that we know is in the key of A, Audacity may estimate the pitch as A if the first note is an A. However, music does not always start on the same note as the musical key it is in, so the detected note will not necessarily be an A. That does not matter because we know the current key and the key we want to change to. Whatever the detected pitch, we will set the "from" pitch to be an A and the "to" pitch to be the C#/Db above that A.

In the image above, the first note detected was actually B4. This makes it the second note in the scale of A major or A minor in fourth octave position (that is, nearly an octave above C4 which is commonly known as "Middle C").

1. Change "from" pitch to A by clicking in the dropdown menu.
2. Change "to" pitch to C#/Db by clicking in the dropdown menu.
3. Observe the octave text box to right of "to" pitch is still at 4, indicating a pitch change down of 8 semitones.
4. Click the upward-pointing arrow to right of the "to" octave text box (or click in or select the box and press Up arrow) to change the octave to 5. This is necessary because the octave number always increases by 1 when moving up through C.
5. We now have the change we want from A4 to C#/Db5, so we could click OK to make the change.

Before changing the pitch, observe that the pitch change could have been entered in other ways. Had we realised that A to C#/Db was 4 semitones, we could have left the pitch controls alone and just entered 4 in "Semitones (half-steps)". It does not matter that the pitch change indicated would have been from B4 to D#/Eb5, because it is the interval of 4 semitones that Audacity is applying.

We could also have achieved an identical result by simply setting the "Percent Change" to 25.992 (if we happened to know that 4 semitones upwards is equivalent to 25.992%).

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, particularly at more extreme settings.

Change Pitch by default does not keep the length of the selection exactly as before. Enable the checkbox Use high quality stretching (slow) if it is important to keep the exact same length, for example if changing the pitch of individual very short notes.

The highest reliable detection frequency is about 1/8th of the sample rate. So for a sample rate of 2,000 Hz, pitch detection will not be accurate much above 250 Hz and for the default project rate of 44,100 Hz, detection will not be accurate much above 5,500 Hz.

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