Jerry Stuckle wrote:
I won't get into the math here, but due to the sidebands (yes, FM has
sidebands, also - the number and strength of the sidebands is
proportional to the deviation and modulating frequency), frequency
response of the modulated signal is proportional to the bandwidth of the
channel and deviation. A 5 kHz deviation can theoretically pass up to
about 5Khz of audio, but in practice it's limited to about 3 kHz (to
avoid adjacent channel interference). This is fine for voice, but does
not work well for music (try listening to music on the AM band, for
instance).

A 75 kHz deviation can easily be modulated at 15 kHz, providing for
better quality music.

You keep amazing me, Jerry! Keep on going, I need some fun going into
the weekend!