Sound Pressure Questions

Factual Questions
1

Okay, not too long ago, I over heard some half-wit claiming that the thumpa, thumpa stereo in his car put out 60,000 dB. He was dead serious about this and seemed honestly to believe it. Now, of course, there’s no way it could be true, but it got me to wondering:

A. How the hell could you generate such a sound?

and

B. What exactly would happen if you did manage to generate such a sound? (Other than you’d immediately be wiped out by the members of Disaster Area for trying to muscle in on their territory.)

2

Check out the current News of the Weird for a description of “dB drag racing”; last year’s winner only reached 177.7 dB.

3

According to my references

dB = 20 log (p/p[sub]0[/sub])

where p[sub]0[/sub]=0.02 mPa. 60,000 dB would be

10[sup]3000[/sup]*0.02mPA = 2x10[sup]2998[/sup] Pa

I don’t think even a supernova can generate that pressure. For reference, if were on the surface of a neutron star, the pressure created by a cubic centimeter of neutronium would be about 10[sup]28[/sup] Pa.

4

Oops, that should have been:

10[sup]3000[/sup]*0.02mPA = 2x10[sup]2995[/sup] Pa

5

Considering that every 3 dB represents a doubling of sound pressure level, I don’t think anything could come close to generating 60,000 dB. As scr4 said, that is a hell of a lot of pressure. Incidentally, death can occur at levels of around 200dB, and 160 dB is recognized as the pain threshold level. Maybe the big bang could have approached that kind of pressure level. Any cosmologists care to confirm this?

6

Decibels is a logarithmic scale. That is an increase of decibels from 20 to 30 is much less than an increase from 30 to 40. So…

10dB is 10x more than 0dB
20dB is 100x more powerful than 0dB
30dB is 1000x more powerful than 0dB

Anything above 85 decibels has potential to cause hearing loss in humans with sustained exposure (in this case hours). Anything above 140 decibels can cause immediate hearing loss to some degree. 60,000 decibels? You’re friend is hugely misinformed. I have no idea what it would do to people nearby but I’d wager his car would explode and anyone nearby would be killed. I wonder if our atmosphere could even propogate such a powerful signal. I’m no scientist but I’d think there’d be an upper limit as to how much compression air can handle before becoming ‘saturated’ so to speak. Just a WAG on my part though.

7

I don’t have an exact answer for this but check out what 160dB did to someone in the water (the LFA referred to is the Navy’s Low Frequency Active Sonar which presumably can produce aroun 215-230dB in the water making a bunch of environemntal groups very displeased as they expect it to have a negative impact on marine mammals):