"Pitch" is the impression we get from the frequency of the sound.
'High pitch' is the sound of a piccolo, a mouse's squeek, or a little girl's voice.
'Low pitch' is the sound of a tuba, a big drum, or distant thunder.
The system of pitch is the whole idea of the 'key' in music.
If the singer hits the 'wrong note', he sounds 'off key' ... that usually means
that he's singing the wrong frequency, and we hear a pitch that doesn't belong.
