The exhaust system is falling apart probably from rust, have it checked soon, you don't want fumes getting into the car.
Sounds are louder when they are closer, because the sound is closer to your ears.
Problem sounds like your hydraulic lifters. Might be a bad one or it can be dirty or even scorched. dvk of nyc.
At night-time there are less sounds from traffic and people - therefore any sounds that are heard seem louder.
A humming noise on a 1999 Park Avenue is caused by bad wheel bearings. When bearings are loose or worn they will create a loud humming noise that will get louder and louder as the car accelerates.
how much the stereocilia of the hair cells are bent
When you accelerate. you are putting presure on the main engine barrens. if they are going bad. You will hear this knocking sound. I don't know how many miles you have on this engine. But that's what it sounds like. But that's not all that can make this sound. You will have to tell more about it and when it started. Did it just start all at once? or did it start and then get louder?
I've had 3 astro's the fuel pumps are just loud has nothing to do with burn out. high pitched whine sounds like it's coming from the back seat much louder in the cargo version.
It sounds like the power steering pump to me. my guess would be that you have a bad or loose belt ( sliping ) or you have a pully that is gonna either come flying off or lock up completely....neither is good. also a tight belt can cause the whine if it is tight the whine could be coming from the pulley bearings (alternator etc)
How's your oil pressure? Sounds like there's a little deamon in the bottom of your crankcase hitting your rods with a hammer? Maybe it's time for a rebuild or better yet, another motor.
Dig a Hole
Very large. the larger the louder.
Because sounds louder than that (and actually somewhat softer) cause permanent hearing loss.