How can pitch be changed? (sound pitch)?

A high pitch sound corresponds to a high frequency sound wave and a low pitch sound corresponds to a low frequency sound wave.

The vibrating object that generated the sound wave will generate a higher-frequency sound wave by vibrating faster. Reducing the length of the vibrating object (e.g. moving your finger closer to the neck whilst fretting a guitar string, reducing the length of an air column in a wind instrument etc.) will cause it to vibrate faster, hence higher pitch; the converse to achieve lower pitch.

Let's take a string off a cello as an example.

To change the sound of a note, you can:

Make the string longer, this makes the note lower

Make the string wider in diameter, this makes the note lower

Make the string vibrate faster, this makes the note louder

Make the string tighter this makes the note louder

The sound is therefore affected by:

length of the vibrating medium,

thickness of vibrating medium,

speed of the vibrating medium,

and the tension of the vibrating medium.

But since the pitch has nothing to do with the volume, the variable "speed of the vibrating medium" is excluded.

By altering the speed of the sound wave