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[Ronny]

j.hall wrote on Wed, 27 April 2005 15:46

Ronny wrote on Wed, 27 April 2005 14:00 How do you figure, Brad. SPL is typically measured at 1 foot or one meter....etc.... WRONG.  loudspeaker sensitivity is measured at 1W/1M (one watt of power based on the nominal load, and having a calibrated type 1 test mic exactly 1 meter on axis from the speaker) load being the measured Ohms of the speaker.  one watt of power is different at 8 ohms then it is at 6, 4, 12, 16.....you get the point, i hope. this happens either anachoic, or half space and should be noted as such by the manufacturer on their white paper (spec sheet) this data is important because it tells you how much power to put to a loudspeaker based on two things.   1.  typical distance between loudspeaker and listener. 2.  desired SPL at the typical listener location, and desired headroom for the system. using the inverse square law you can plug in all the parameter and come up with a power setting. for every 3 dB more you want out of a speaker you have to double the power!!!!!!!!!!!!! I.E.  if i have 80 dB coming from my questeds, and the amp is pushing 10 watts to each speaker, i have to supply 20 watts to each speaker to just get 83 dB out of them.......which means i have to push 40 watts each to get 86 dB, you see where i'm going with this......i hope. SPL is measured where ever the heck you are standing and is only valid for the power the speakers are emitting and the exact location you are taking the measurement in.  SPL readings must be follwed with what weighting you used for the measurement as A weighted, C weighted and un-weighted are the most popular and they yeild very different results. i hope this can be applied to headphones vs. loudspeakers without me having to spell it all out.

Ok, I think I understand what you are saying, thanks for the explantion. Question: SPL is relative to distance and the closer you are to the speaker or headphone speaker the higher the SPL, so isn't this still all gain relative, gain meaning how much power you have to apply to get x SPL reading. In that case wouldn't headphones and loudspeakers have the same amount of SPL relative to watts? I enjoyed your explanation, but I'm still confused on how a little speaker can move more air molecules than a speaker 10 times larger.

[Andy Simpson]

It's a little like you'd need a kilo of cyanide to poison a man in a swimming pool, but a crumb to poison him in his drink - a question of efficiency.

Imagine the damage that in-ear monitors can inflict - talk about efficient!

Andy

[zetterstroem]

typically headphones need max 0.1 watts to rip your head off.... so would (some) speakers if you listened an inch away.....

do you??

so when i strap on my sennheiser hd265 and turn on my ipod (european volume cap OFF!!) i can easily reach 120dB when listening to marilyn manson  

that's a bit more than most speakers..... although genelec advertised with 136dB at two metres for one of their LOUDspeakers..... they sound absolutely awful by the way.... even JBL PA system sound better!!!

[DanDan]

http://www.digital-recordings.com/hearing-test/ht-products.h tml

It works.
DD

[dcollins]

zetterstroem wrote on Wed, 27 April 2005 03:26

on the other hand headphones usually has less distortion than speakers.... and thereby less impact on your hearing...

The distortion of the transducer has nothing to do with hearing damage.  It's all in the midband SPL.  You are FAR more likely to damage your ears with headphones than loudspeakers.


DC

[dcollins]

lambda wrote on Tue, 26 April 2005 23:43

The other day, when I was setting up my brother's video game systems to work with his television, I realized that I could no longer here the high frequency noise of the flyback transformer. I did a sine sweep and I couldn't get much above 15 kHz (which makes sense, as the flyback is about 15.75 kHz).

15,734 for those keeping score at home.

I'd say your hearing is normal.  They don't go over, IIrc, 8k in a normal test, since speech is all they are after.  They do have wider band tests, as well and ones that include noise-masking, but you probably have to go to a big-deal specialist.

DC

[turtletone]

I had one done awhile back and i'd be amazed if those headphones they handed me could output 12k. They looked like they were purchased used from a 1950's studio auction. When I got my chart back, I called the doctor and asked if everyone else he tested had a -12db drop at 10k. He said mine was much better than most. I would suggest going to someone that is geared more towards audio professionals. When he played 100hz, I asked him if the left side was supposed to be buzzing (sarcatically of coarse), he said that was normal.  

[OTR-jkl]

TurtleTone wrote on Wed, 27 April 2005 20:48

When he played 100hz, I asked him if the left side was supposed to be buzzing (sarcatically of coarse), he said that was normal.

He's right. All ears do that - don't they...??

[Jerry Tubb]

Should you get your ears "candled" before the hearing test?

Guess if you brought your own headphones to the audiologist's, you would blow the roof off the test.

At age 50, I almost never use 'phones, keep those monitor levels at 85-90dB, wear earplugs to loud movies and sporting events. 16k still fine.

Sleeping with earplugs can do wonders after a long day of mastering loud rock with lots of 3k-10k content... damn those hi-hats & tambourines!

[bblackwood]

JayTea wrote on Thu, 28 April 2005 02:39

Should you get your ears "candled" before the hearing test?

Arghhh, never!

Quote:

wear earplugs to loud movies and sporting events.

Same here, some people look at me weird, but I'm not leaning in asking them to repeat what they said into my good ear...

[turtletone]

has anyone tried those really expensive piston earplugs that increase the suppression as the level goes up?

[bblackwood]

TurtleTone wrote on Thu, 28 April 2005 05:04

has anyone tried those really expensive piston earplugs that increase the suppression as the level goes up?

Never heard of 'em - can you tell us more so we can find some info? Sounds interesting!

[Level]

Sonic ear valves have been around over 20 years. Is this what you are speaking of?

http://www.northsafety.com/can/en/bs_product.html?GID=987

Very familiar with them.

[j.hall]

Ronny wrote on Wed, 27 April 2005 15:12

Question: SPL is relative to distance and the closer you are to the speaker or headphone speaker the higher the SPL, so isn't this still all gain relative, gain meaning how much power you have to apply to get x SPL reading.

um, sort of.  the inverse square law applies here.

3dB rise in volume by doubling the power to a speaker, a 6dB loss in volume by doubling the distance the listener is from the loudspeaker.....see the dilema here?

if you are 100 feet away from a giant loudspeaker cluster at a concert venue, and your meter says 100dB Un-Weighted, you'll have to walk 50 feet closer to the cluster to get a reading of 106dB (this is assuming the acoustical environment is the same in both positions).......so, 25 more feet and you're only up to 112dB, 12.5 feet, 118dB.....

here is what you are missing in this.

headphones are right on top of your head.

Brad never said that headphones are ALWAYS louder then any speaker system known to man

you are confusing overall "max spl" with potential.

Quote:

In that case wouldn't headphones and loudspeakers have the same amount of SPL relative to watts?

NO.  that's exactly my whole point.  every single speaker made is different.  and this is why manufacturers (the good ones at least) publish their sensitivity tests.  the 1W/1M (one watt, one meter) numbers are crucial to this whole conversation.  you have to understand exactly what that number means and it's implication, to understand why your thought process is off.

the point is this.

a pair of headphone strapped to your head (cause no one will ever listen to cans any other way, just as you won't strap a pair of questeds onto you head) have the POTENTIAL (key word here) of being much louder and more damaging to your ears, at lower power levels then any loudspeaker on the planet (at least that i've come across......

Quote:

I enjoyed your explanation, but I'm still confused on how a little speaker can move more air molecules than a speaker 10 times larger.

proximity, and potential.

my questeds are having to move the air in the entire room to reach levels that my beyers only have to move directly on my head pumping sound directly into my ear canal.

this is why most headphones have a lower sensitivity then loudspeakers.....they're actually trying to protect you from having blood run down your neck.

[dcollins]

Level wrote on Thu, 28 April 2005 05:03

Sonic ear valves have been around over 20 years. Is this what you are speaking of? http://www.northsafety.com/can/en/bs_product.html?GID=987 Very familiar with them.

Are those the ones with tiny batteries in them that you once reffered to?

DC