Explanation on the Relationship between Tempo and Pitch in Music

Tempo (time-stretch): Changes the sound to play at a faster or slower speed than the original, without affecting the sound pitch. Here without affecting the sound pitch means the pitch of the signal is intact while changing its speed (tempo).

Time Stretching” is the reciprocal process to Pitch Shifting. It leaves the pitch of the signal intact while changing its speed (tempo) while Pitch Shifting is a way to change the pitch of a signal without changing its length. The tempo of an audio file, measured in beats per minute (BPM), can be changed using various software tools and online platforms. An effective tempo changer often allows the user to modify the BPM without altering the pitch.

Pitch: Changes the sound pitch, without affecting the sound tempo or speed.

For changing the tempo, you have to resampling the original signal appropriately and for this you need an algorithm. The basic idea is that you have to first calculate the whole pitch periods in a processing buffer and repeat the period of pitch to lower or delete inorder to increase the tempo.

For changing the pitch which often called Pitch Shifting, is a way to change the pitch of a signal without changing its length.Typically, good algorithms allow pitch shifting up to 5 semitones on average or stretching the length by 130%.[TheDSPDimension].

For more about Time Stretching And Pitch Shifting visit following links –

http://www.dspdimension.com/admin/time-pitch-overview/

http://www.guitarnation.com/articles/pitchtempo.htm

Some of the Music software Tempo and Pitch Modification

Audacity (Mac, Windows, Linux):

A popular open-source audio editor, Audacity allows tempo change, pitch shift, and supports various audio formats. It also features an equalizer and reverb effects.

GarageBand (iOS, Mac):

This app lets users change tempo and pitch easily. It supports a range of file formats and provides real-time changes.

Music Speed Changer (Android, iOS):

This app enables changes in audio speed and pitch. It supports formats like mp3, wav and more.

Anytune (iOS, Mac):

This application lets you change the tempo and pitch, provides an equalizer, and allows you to create playlists.

Amazing Slow Downer (iOS, Android, Mac, Windows):

This software is perfect for slowing down or speeding up music. It also features pitch shift options.