Transposition
Transposition is a pitch variation that does not change the sound’s duration. All the components of the spectrum are therefore shifted by a chosen interval. Transposition is often used to thicken a sound, double a melodic line, or create chordal effects.
Transposition, also called harmonization (from the English word “harmonize,” meaning to create harmonies), alters the pitch of a sound while leaving its duration unchanged.
Transpositions with Pitch Accum (2 pitch-shifters)
Sonogram of the “Transpositions” sequence
The opposite operation is called time-stretching/compression, i.e. changing the duration without affecting the pitch.
To obtain a stretch, you must combine speed variation and transposition. For example, reduce the playback speed to 0.5. This lowers the pitch by one octave and doubles the length of the sound. Then raise the transposition to 2 to compensate for the pitch shift produced by the speed change. The pitch returns to its original value, and the duration remains doubled.
This manipulation affects the timbre, which is pushed around a little, but for many sounds the alteration is barely noticeable.