Can bass waves actually hurt you?

[billfitzmaurice]

Note that you need many megawatts of power to produce 170 dB in this example, with typical loudspeaker electroacoustic efficiency.

Your figures of typical loudspeaker efficiency are incorrect. An average direct radiating driver operates with 3-5% efficiency. When the number of drivers operating within 1/4 wavelength of each other is doubled the radiating efficiency is also doubled, via mutual coupling. There is a caveat: along with each doubling of drivers and efficiency the upper corner frequency is reduced by a factor of 0.7. The result is a finite limitation of the total system efficiency at roughly 25%,(D.B.Keele, 'Maximum Efficiency of Direct Radiator Loudspeakers', 91st AES Convention, October 1991; preprint 3193).

 

[lhoward]

To answer the OP, any acoustical event of sufficient SPL can cause medical problems for humans. Distress or damage from an electric bass guitar depends on the system providing the amplification, but would most likely be limited to your ears. That's not to minimize the damage because once seriously damaged, hearing it doesn't return to normal. I play with a pianist and drummer in one group who have serious hearing loss. I have to speak very loudly and they have to be looking at me to understand what I'm saying on stage on a gig with a lot of background noise. Unfortuantely, a few years ago I played a gig with a group sub'ing for their bassist. Even though I got my ear valves in after the second tune, I still wound up developing tinnitus in my left ear on that gig from their very loud drummer.

The reference below documents SPL's up to 320 dB. Duration periods are not included, but would only apply at levels about 120 dB and below for hearing concerns.

http://www.makeitlouder.com/Decibel Level Chart.txt

Here are some extracts from the above reference (dB level given at the beginning of each line) for the info of those not inclined to browse to it (its about a 14-page document):

"85 BEGINNING OF HEARING DAMAGE, EARPLUGS SHOULD BE WORN

116 HUMAN BODY BEGINS TO PERCIEVE VIBRATION IN THE LOW FREQUENCIES -REF.1.1986

133 (N)GUNSHOT- EAR LEVEL, MAY VARY GREATLY TO SIZE AND TYPE OF GUN,
DURATION CONVERTED TO ONE SECOND, PEAK LEVEL MAY REACH 140-160

137 HUMAN BODY VIBRATION IS STRONG -REF.1.1983

140 EXTREMELY DAMAGING TO HEARING NO MATTER HOW SHORT THE TIME EXPOSURE

141 HUMAN BODY BEGINS TO FEEL NASUEA AFTER A FEW MINUTES -REF.1.1983

142 (P) INSIDE A CAR WITH TWO PRO 18 INCH WOOFERS AND 300 WATTS EACH -REF.1.1983

150 HUMAN SOUND EXPERIMENTS DOWN TO 1 TO 2 HERTZ - REF.13.

152 HUMAN VIBRATION IS PAINFUL AND ALSO FELT IN ALL JOINTS -REF.1.1983

153 HUMAN THROAT IS VIBRATING SO HARD IT IS ALMOST IMPOSSIBLE TO SWALLOW -REF.1.1983

171-150 (P)WORLDS LOUDEST CAR STEREOS, UP TO 80 SPEAKERS, 32 CAR BATTERYS,
100,000 WATTS, 125-138 (N)

173-164 (P)BASS INJECTION TESTS, EXPIERIMENTAL ELECTROMAGNETIC TYPE SPEAKERS -REF.1.1987

191 (N)BOMB-VERY SMALL 1 LB. OR GRENADE, VERY CLOSE PRESSURE MAY EXCEED 210 db (P)

195-190 (P) HUMAN EARDRUMS RUPTURE 50 % OF TIME -REF.2.

198 (P) HUMAN DEATH FROM SOUND (SHOCK) WAVE ALONE. -REF.2.

215 SPACE SHUTTLE LAUNCH EXHAUST, APPROXIMATELY 3 MILES PER SECOND"

 

[JimmyM]

Excellent!

 

[ninefingerbass]

In response to your question. When you are dealing with low frequencies, you need a large, massive power source to output the frequency. The waves are farther apart and it requires more energy to get it out and make it travel. Sound is air pressure without getting all technical. The less/more air you press the faster/slower the frequency and the higher/lower pitch your hear.

You have a sound wave that cycles through, for example 60 Hz cycles 60 times in one minute. If you kept doubling 60 you will eventually get 120, 180, 240, 300, 360, 420, and finally 480, which to most of us is also know as A or a little above A. Since A is 440 Hz, divide that by 10 and you get 44 Hz. To keep this simple I'm going to use whole numbers. 44 Hz is less than the second hand traveling to get to the next second. Think about it. It means that the sound is traveling slower than a second, since we interpret many things to this relative time. At certain frequencies there are decibels that are needed. In order to project these frequencies out, there needs to have a massive power source. Look at your cell phones and car radios, or even GPS, satellite radio, wireless internet, whatever it is you are using look at it. Does it require a huge antennae to project your transmission or does it need a huge receiver to get your favorite station or that call from you ex., maybe your favorite website? Whatever the case, technology has made rcvrs much smaller since components in circuitry has become smaller and nano technology has been introduced along with semi-conducters and transistors. This has cause for antennaes to become smaller. Which means lesser dB thus proving that higher frequecies require less energy.

Why is this relevant? Well when you look at those products you bought, they all have little tiny xmtr/rcvr. Those require less energy, since they are higher frequencies. When you have higher frequencies, it travels much further than lower ones. Why do you think guitarist need only 50 watts to be heard and we need 300 watts? Since our frequencies are much lower it requires more power to push that air so it can travel the same distance. This also requires dB's which is why when you see a radio that has 45 dB, it's going to be loud. Even -dB are dangerous. But the lower the frequency the more dB you will need to push that air so it can travel. When you see 53Hz at 170dB...That's F-ing insane!!!! If it can crack glass, I'd hate to have an ULF at 300dB+ coming at you. It's air pressure. What is a storm, tornadoe, hurricanes, superman's breathe a result of; air pressure. It pushes air to make sound.

I work on a naval vessel, with SATCOMs and UHF. Nothing I deal with goes underwater though if it were I'm not at right to say. Either way here's the deal. If you were to get close to a high frequency antennae with alot of RF power coming out, you are going to get burned. Even HF circuits need lots of power to push out. HF travels far but can be bounced off. It's a dirty frequency as far as reception but it can get the job done. HF can travel half way around the world if there was enough output. When we get into VLF, we are dealing with a massive energy source that can kill you. The output power pushing it to travel is so immense that it is considered high voltage and can cause death.

Then you have ELF, and SLF. I doubt most of this is used nowadays except for underwater since water can carry the soundwave much further than the air above it. Why? Because of the air molecule being further apart than the water. When you deal with molecules and soundwave or anything that requires energy transfer, the closer something is the better it will travel. I.E. Metal with wire to metal. Electrons will travel much further on metal than it would on anything else. It's because the molecules are so dense the transfer rate is much faster. Now how much faster or slower depends on the kind of metal.

I didn't not mean to go off course but I thought I might give a little input on the topic. I missed a few areas to make it flow better but I hope you get the jist of it.


Basically, if you have enough power and the equipment to handle it, you can produce a low frequency strong enough to push you back, jolt you, make you go deaf, maybe even kill you. I know I wouldn't mess with anything like that but that's just me.

 

[GCool]

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[A9X]

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So? Do it in half space. Continuous.

 

[GCool]

Well, if you're really good, you get a trophy, a free polo shirt and a baseball cap.

Blasting a phone booth, that is. I don't know what the award is for poo eating

Why are ALL your post SO nevitive?

I receved apm form a guy in here saying dont take any thing Jimmy says to hart.. hes like that all the time... why do you want to be that the POO guy?


I was attracted 1st on here but it ok .I know what I know with my degree/ achievements behind me.... enough with the arguments. If you don’t believe what I have to say that ok with me. LET’S STAY ON TOPIC!


If you or anyone elce have a problem with what I have done in the spl world, please pm me with your thoughts. Thank you.

 

[A9X]

Why are ALL your post SO nevitive?

Because SPL drag racing has no relevance to acoustics anywhere else but in a phone box. The whole point of it is to impress the stupid into spending lots of money on overpriced car audio gear.

I wish I'd known they gave out trophies for masturbating when I was in my teens.

 

[GCool]

Meh. Do it wideband in a stadium and I'll be impressed. Otherwise the PEC comment stands.

back in 2005, Usaci was wanting the record for loudest building. At that time W/F was held in Bartal Hall in KC, Mo.
Ralp R. pres. of USASCI, stoped the experment after 159.3db when the lights where fallin from the roof ad the floor was shaking bad. Ralph was afrad of the build having major damage that was unable to be fixed.

note
that was over 90 of the wrold LOUDEST car there playing 65hz. The least amount of power from any car was about 2k watts up to 170k watts.


there ya go!

 

[GCool]

Because SPL drag racing has no relevance to acoustics anywhere else but in a phone box. The whole point of it is to impress the stupid into spending lots of money on overpriced car audio gear.

I wish I'd known they gave out trophies for masturbating when I was in my teens.

Maybe to you it was point less. But none the less it is a sport. Like fishing or drag racing either one I’m not interested in but still a sport. I still don’t knock them down for there accomplishments.
With out spl comps there would be no up grading of equipment from manufactures. No drag racing? No up graded performance parts! Get the hint?
None the less I know a few good friends that received jobs with NASA and the military from there acoustical knowledge.
I also did R/D for a few companies witch was great!

 

[GCool]

Because SPL drag racing has no relevance to acoustics anywhere else but in a phone box. The whole point of it is to impress the stupid into spending lots of money on overpriced car audio gear.

I wish I'd known they gave out trophies for masturbating when I was in my teens.

1st you might want to use WORD to help you on your typing. I know it helps me.
What does putting a phone in a box has to do with any thing?
Do you have any credits to back your word?



ENUFF ON TRASHING ME or CARAUDIO
Pm if you need to!

 

[Rick James]

1st you might want to use WORD to help you on your typing. I know it helps me.

Dude, if your semi-literate posts are what you get after using spell and grammar check you need new software. One reason why you don't get any respect for your views is that they seem to be coming from someone who isn't even old enough to drive, let alone compete in spl drags. Reason two is that real people with real professional credentials use real names, not silly monikers, and they fill out their personal profiles. Reason three, WE DON"T CARE. This is a bass players forum. IMO you're just wasting bandwidth.

 

[Handyman]

Your figures of typical loudspeaker efficiency are incorrect. An average direct radiating driver operates with 3-5% efficiency.

I didn't realize that speakers are so inefficient. So does most of the power just get dissipated as heat?

 

[A9X]

Maybe to you it was point less. But none the less it is a sport. Like fishing or drag racing either one I’m not interested in but still a sport. I still don’t knock them down for there accomplishments.
With out spl comps there would be no up grading of equipment from manufactures. No drag racing? No up graded performance parts! Get the hint?
None the less I know a few good friends that received jobs with NASA and the military from there acoustical knowledge.
I also did R/D for a few companies witch was great!

1st you might want to use WORD to help you on your typing. I know it helps me.

Really?

Big deal on 'improved spec' parts for SPL comps. Using a resonant peak in a tiny enclosed space has no relevance to acoustics outside of a phone box (a similar volume; now do you get it?). Want to impress us? Outperform Clair Bros.

 

[billfitzmaurice]

I didn't realize that speakers are so inefficient. So does most of the power just get dissipated as heat?

Yes, and that's why the number one cause of driver failure is excess heat. It's also why if you want to go loud you're better off with more drivers driven with a moderately sized amp than fewer drivers driven by a high power amp. Using more drivers increases system efficiency, and the drivers don't get as hot.

a phone box (a similar volume; now do you get it?).

He's probably never seen one, they disappeared from useage in the US decades ago.

 

[A9X]

I didn't realize that speakers are so inefficient. So does most of the power just get dissipated as heat?

Yes. 5% is a good number, unless it's a compression driver.

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Look at the EFF column.

 

[A9X]

He's probably never seen one, they disappeared from useage in the US decades ago.

Fair enough. There are still some here.

 

[GCool]

ok ,
Blowing in to a mic is NOT audio!
With the New meter (term lab) the clement don’t not change the way the mic reads. Turning the defrost on will NOT help with the new meter. Now with the old mics like B&K, Custic, and Audio Control it seems to help a lill.
Now 3-4 years ago the spl world (DB draracing. USACI, MECA, ISACI) switched to the Term lab for the consistency like NO other.
I have played on over 100 different mics thou this country. What I have found ad other spl people found that the old mics like AC is very inaccurate for 2-8 db gain.
Legal readings are measured on the dash and the car all sealed up. Outlaw is measured is any where forward for the B-pillar and you can have a door or window up or down. With outlaw reading you tend to find you gain 1.5 3 db by opening up the car.
Now I have devoted 10 years of my life for these study’s not to mention 5x world champ and countless records. I have a degree of digital audio from S.A.E. So im not just a kid with some subs in the trunk.


I didi not want to come in here and get in to a big ego contest with any one.

So you know the lousedest car in the worls is mow hitting 180.2 db Scott Owens with his extrem f250. Powered by Pioneer!
Still wating for some one here to prove me wrong.

Utill then keep bashing me with you un-knowledgable thoughts!

Have a nice Day!
Greg McCool
[email protected]

 

[GCool]

Really?

Big deal on 'improved spec' parts for SPL comps. Using a resonant peak in a tiny enclosed space has no relevance to acoustics outside of a phone box (a similar volume; now do you get it?). Want to impress us? Outperform Clair Bros.

Now you are all changing this around. From football fields to phone booths. Whats next?
Bill 1st said that a car can NOT do the #s that I mentioned. He's wrong ad dont like to be told so.


Im not here to impress you!
But since you asked, we helped out companies like JBL, Crown and the Military.
good enough for you yet?
I can go on and on!
Now Clair Bros. is a GREAT company. I love to hear his wife sing. M.M. is one of my favs!

 

[A9X]

Now you are all changing this around. From football fields to phone booths. Whats next?

Perhaps some comprehension on your part? Or reading my posts properly? If you wish to prove Bill wrong, take apart his maths.