In Bart Sibrel´s Astronauts Gone Wild, it is said that Al Bean and Geene Cernan contradicted each other when answering if the descent engine could be heard.

I know that Cernan said it was hard to tell the difference between feeling and hearing the sound, probably because he was meaning he knew the engine was loud by feeling the vibration through the contact with the ship.

Besides I know Al Bean said it couldn´t be heard, I don´t know exactly what was his wording and context.

Do you know anything about this case?

I would imagine that they felt more than heard the engine firing. Since sound doesn't travel through a vacuum, any sound or vibrations would be coming through the inside of the ship.
Another point: I'm old enough to have watched the moon walks live on tv. I can remember hearing the hammer stikes once when one of the astronauts was hammering a core tube sample. I fiured it was vibrations traveling through the suit and being picked up by the mike.

__________________
I'm not a scientist, but I play one on the internet.
http://www.rrac.org

Can or could you hear the jet engines on a concord?

When that was traveling twice the speed of sound then the sounds from the engine would not be able to keep up with the plane so it would be equivalent to a vacume regarding sound.

Actually, the engines were so loud that it was a problem for the passengers. Apparently it was quite unpleasant.

__________________
Quaeso quousque humi defixa tua mens erit? Nonne aspicis, quae in templa veneris?

Yes, sort of.

You wouldn't hear the exhaust or the sonic boom. You're right in that a supersonic aircraft would outrun that sound (outside frame of reference).

However, the vibration of the engines would carry through the metal and interior of the plane (moving frame of reference) just fine. This is general relativity in the real world.

The Supreme Canuck's right. The Concorde was reputed to be uncomfortably loud.

__________________
In Fallout 3, 'happiness' is a warm junkyard dog and a loaded gun. It's mostly the loaded gun.
- Moose's one-line review.

"your going to regret that one. You are now a colonoscope...
- Chrissy, corrupting PraedSt's wish.

Dave Scott on the Apollo 15 LM liftoff transcript on ALSJ:

He was referring to the LM ascent engine however.

__________________
"We need rigidly defined areas of doubt and uncertainty!"