David Looser wrote:

wrote in message
In any speaker, when you put the volume up high, there is more
electric buzzing.

1) What is this buzzing called?

If it's a "buzzing" sound, it's usually called "buzz". If it's more of a
"humming" sound then it's called "hum".

2) What specifications in a speaker reduce the amount of buzzing as
volume is turned up? e.g. low/high impedance, sensitivity, etc.

None at all, because it's not caused by the speaker. It's caused by pick-up
of mains-borne interference earlier in the system, ie. the amplifier, it's
wiring, or the source components, CD player, tuner etc.

Other possibilities might be responances or coil-rub.

Graham