In message ,
Bill Sheppard writes
A body of such density and extension
should be prone to vibrating, or ringing
for long periods of time, especially after
a large object has struck it.

Check out this 'clearinghouse' of info on BH ringdown-

http://astrogravs.gsfc.nasa.gov/docs...down_date.html

This could explain the observed
phenomenon of "black holes" producing
sound waves.

"Sound waves" in the near-perfect vacuum of space? Or acoustic pressure
waves in the fabric of space itself, propagating at c, otherwise known
as 'gravity waves'?

On a related note (no pun intended), here is an excellent piece
addressing the "speed of gravity" question-

http://www.metaresearch.org/cosmolog...of_gravity.asp

This paper also clarifies the distinction between gravity and 'gravity
waves'. The mainstream almost universally blurs the distinction,
creating the impression that gravity itself "propagates" from its
source, presumably at c.

Corrections welcomed, but aren't _changes_ in gravitational fields
supposed to propagate by gravity waves? AFAIK the existence of gravity
waves has been fairly well confirmed by Taylor and Hulse's binary pulsar
observations, though everyone will be happier when direct observations
are made.
The speed of gravity is a lot more controversial, and I'm not sure it
can be measured. There seem to be a lot of people objecting to Ed
Fomalont and Sergei Kopeikin's measurement.
I know Tom van Flandern has some "interesting" views on this.
--
"Forty millions of miles it was from us, more than forty millions of miles of
void"