High-pitch results when key fob is out of bounds (4)

I believe the answer is:
alto
'high' is the definition.
(similar in meaning)
'key fob is out of bounds' is the wordplay.
'key' becomes 'alt' (the Alt keyboard button).
'is out of bounds' says to take the centre (the bounds or edges of the word are removed).
The middle letter of 'fob' is 'o'.
'alt'+'o'='ALTO'
'pitch results when' acts as a link.
I am not very happy about this link. Some or all of it may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for alto that I've seen before include "A singing voice or pitch" , "Woman's singing voice" , "Voice part" , "someone to sing" , "High male singing voice" .)
