[scompton]

I posted this on another thread for how I measure SPL for my IEM. I'm not sure how accurate it is. I've been thinking about going to an audiologist. If I do, maybe I can see how accurate this test is.
http://www.head-fi.org/forums/showpo...&postcount=102

In the same thread, Skylab posted his method of measuring full sized cans.
http://www.head-fi.org/forums/showpo...5&postcount=42

I listen for 9 or 10 hours a day, so it's important for me to not listen too loud. The day I bought my SPL meter, I measured the SPL on the DC Metro on my way home. The general level on a train was 90-95dB with peaks up to 120dB. Announcements were all over 100dB. Made me happy that I use an IEM. I listen at a low enough level that I can still hear some of the noise even with the IEMs in my ear.

For the poster who listens to their iPod an 3/4 volume, you're listening too loud unless you are listening with non portable, high impedance headphones. Even with my im716, which I've read has an impedance over 100 ohms, I don't listen at 3/4 level.

 

[ADD]

Hi Scompton,

It would be interesting to see how your test compares to the method an audiologist might use (the latter test really does intrigue me though, given the huge difference in sound and perceived volume across the frequency spectrum I experience if the ear seal on my UM2s are even the slightest bit compromised. If the test really looks like it works, though, I will be going back to my audiologist too!).

One thing that I would mention about the test you did is that the shape of the ear canal has a very significant on the way sound reaches the ear drum -even though we can eliminate any considerations as regards the effects of the pinna when it comes to IEMs.

I came across this very interesting article a couple of weeks back. In it the author touches on the relationship between IEMs in the ear. He mentions concepts such as having to use individualised notch filters, etc. It was something I had not really even thought about until reading the article.

http://www.linkwitzlab.com/reference_earphones.htm

Sure enough after running some tone sweeps of my own, I found I had this same notch at around 5946 hz with my UM2s. Not only that, but it was quite huge - around -7.8 dB. Someone else would have a different "notch" depending on the characteristics of their ear canal and the type of IEM they are using.

One thing I might consider changing in your testing methology - making a fake ear canal out of plasticine. That way you can try to emulate the canal shape better and get a perfect seal on your IEM seal and the meter seal at each end. Plus the plasticine wouldn't throw around and amplify sound reflections and thus skew the frequency response to the same extent that hard wood does.

 

[MICH62]

I've found this site very informative :

http://audition-prevention.org/site/...e_du_bruit.php

You can translate it in English at the end of each page.
It insists on the fact that not only sound level matters but exposition time is as much if not more important.
In fact, the truth is that these two parameters can't be dissociated.
It seems that under 80dB, listening can't be harmful for your hearing and you can enjoy your favorite music as long as you want BUT it does not mean that you won't feel any fatigue which can appear from 75dB level.
The 85/90dB level is commonly considered as the dangerous threshold, repeated daily sessions at or above this value can lead to serious dammage and don't be fooled, at this level, it's insidious because pain treshold is at 120dB.
At last, for sure we are not equal in SPL resistance...but I don't know how this can be determined/measured.

Also, for the SPL meters A/C scale story, I've found this on wikipedia :

http://en.wikipedia.org/wiki/A-weighting

These are weighting curves.
A curve seems to be the more used and C curve is for louder sounds.
I readed somewhere that A curve is for levels up to 85dB and C one above 85dB.

After reading all this, I bought a cheap SPL meter just to have an idea of my listening level and correct
it if needed...
It may sounds as a pathological reaction but, well, I would like to listen to my headphones for a looooooooong time, without added devices in my ears...

 

[ADD]

Well I've got a real issue with the different weighting scales. I really have to wonder about the true validity of standards and measurements under the "A" weighting system - it rolls off significantly at frequencies to which humans continue to have threshold sensitivities (-20dB at 100 hz is a rediculously useless - if not dangerous - weighting in my opinion - and it is all but completely and utterly useless for applications as regards music).

Unfortunately I have yet to find any "C" weighted noise exposure scale - as you say the "C" weightings only seem to make an appearance when it comes to loud or percussive sounds. Infact I have only seen "C" weightings in terms of exposure to impact type sounds - explosions, etc.

Bootom line is stuffed if I'm going to follow the "A" weighting exposure rules. I turned my TV up to 85dBA this afternoon and the sound pressure level drove me absolutely nuts within 10 seconds. And yet it's stated that 85dBA is OK for up to 8 hours continuous exposure. No wonder we live in a world where we are always having to repeat ourselves

 

[Albatross05]

One thing is for certain. You should never try and rely on whether or not you experience pain or discomfort as any kind of indicator. I've heard things that were so loud it was almost painful before but those things were extremely loud. Hearing damage with headphones occurs because you are exposed to a certain level of noise for extended periods. Therefore, damaging levels will not necessarily even be the slightest bit uncomfortable. If you are thinking that you're not damaging your hearing just because you don't feel any discomfort, think again. You might not be but it's not a sure bet.

 

[fraseyboy]

Quote:

Originally Posted by scompton /img/forum/go_quote.gif I posted this on another thread for how I measure SPL for my IEM. I'm not sure how accurate it is. I've been thinking about going to an audiologist. If I do, maybe I can see how accurate this test is. http://www.head-fi.org/forums/showpo...&postcount=102 In the same thread, Skylab posted his method of measuring full sized cans. http://www.head-fi.org/forums/showpo...5&postcount=42

Interesting idea's. Just wondering: What foamies are you using on your UM1's? They look like the new shure black foamies. Are they any good?

 

[scompton]

Quote:

Originally Posted by fraseyboy /img/forum/go_quote.gif Interesting idea's. Just wondering: What foamies are you using on your UM1's? They look like the new shure black foamies. Are they any good?

They're the large Shure black foam tips. Because of my ear geometry, they're the only tips that I can get a good seal and isolation with the UM1s. I can use medium tips with my im716 since they go further in my ear. The UM1 is essentially a canal phone for me. I just barely goes into my ear.

 

[d.phens]

Quote:

Originally Posted by oicdn /img/forum/go_quote.gif Kinda sucky if you have IEMs...cause the only way you can tell if it's too loud, is if you have to second guess "is this too loud?"

Just turn the volume down to 0 after your listening session and in the beginning of each one slowly turn it up listening to some pop preferably (pop songs lack dynamics) - once you start hearing all the details in the music in every frequency range, leave it this way...
That way you even protect your hearing and headphones themselves from damage that some amps can cause when you turn them on.

 

[TheVinylRipper]

The unit of sound measurement is the Bel, named after Alexander Graham Bell. The deci-Bel, or dB is defined as one tenth of a Bel. The dB is used since the Bel is a little too large a unit to be comfortable to work with, just as you would not measure the dimensions of a matchbox in meters.

An increase of one dB is just barely noticeable to the human ear.

An increase of of ten dB is perceived as a doubling of loudness to the human ear.

Every ten dB increase is an increase of ten times in the intensity of sound pressure.

So a twenty dB increase is one hundred times as powerful and a thirty dB increase is one thousand times and so forth.

An increase of 3.01 dB is a doubling of sound power.

Calculating dB changes from power level changes is easy, the formula is {10 log (P2/P1) dB} where the log is to base 10. The log of 2 is .301 so ten times that is 3.01 dB.

So an increase from 85 dB to 115 dB equals 10^3 which equals one thousand times the sound power.

As for using lawnmowers or vacuum cleaners as a standard for loudness, one should take into consideration that such devices vary quite a bit in their sound output. I have a Honda Harmony mower which is surprisingly quiet, you can hardly hear it inside the house when cutting the grass.

Strangely enough, vacuum cleaner manufacturers in the US are reluctant to make their vacuums too quiet, since Americans tend to equate louder vacuums with a more powerful suction. Just like people tend to think that the louder car is the faster one. Once you get your Mustang GT's doors blown off by a Mitsubishi Evo X, you will change your thinking on that subject.

 

[jriems]

Just as a real quick tip: Rather than spending the time to make a cardboard attachment for my SPL, I just pick up an old CD, hold it on the earpad, and put the SPL up to the spindle hole. Works like a champ.

I also usually take a second reading with the SPL right up against the driver, and sort of average the two. Usually, the measurements are not very far off from one another, though.

 

[1Time]

Quote:

Originally Posted by flargosa /img/forum/go_quote.gif I have read that listening at loud volumes can permanently numb your hearing, I have also read that sound above a certain decibel can damage your hearing, but how can a person tell what is safe and what is not?

I didn't take the time to read this long thread, but the simple way to tell if the volume is unsafe is if you remove your cans and detech a ringing in your ears.

BTW, fire crackers, riding lawn mowers and live rock bands are very good at providing unsafe sound levels. Each are capable of permanently damaging your hearing to include partial hearing loss and tinnitus.

 

[wae5]

I listen to classical music with a wide dynamic range. I start with a volume which is like sitting in row fifty. After a minute or two I lower the volume to a level equal to that found at the back of a very large hall or even in the lobby. At first this seems too soft because I must pay very close attention or even strain to hear details but soon my ears come around and adjust the preceived volume upwards on their own to a comfortable listening level. Sometimes, like right now, I even lower the volume again because what seemed to be too soft just a while ago is now too loud. The bottom line is my ears like it louder than I do.

 

[MICH62]

The dB level/exposure time chart states that you can listen 85dB sound level for 8 hours a day before it begins to be harmful for your ears...they do not say that it's 8 hours of continuous listening, of course.
Even with frequent pauses, the daily exposure time remains the daily exposure time.
The only difference between continuous 85dB listening during 8 hours a day (I doubt you'll do this without pause !) and the same listening level during 8 hours a day but with pauses is that, in the first case you'll be much more tired than is the second...if you ever succeed to hold this level during such a long time

Do not forget that they also stated that from 75dB listening level, fatigue is another important parameter, depending on each one's resistance.
Also, it's not because you find that 85dB is an incomfortable listening level that it is harmful for your hearing before reaching the fateful 8 hours.
Each person has a "comfortable" personal listening level which is not the same for everybody and I think that a wise idea is to maintain this favorite level under the limit which is known to be harmful for almost anybody.

 

[Televator]

Quote:

Originally Posted by 1Time /img/forum/go_quote.gif I didn't take the time to read this long thread, but the simple way to tell if the volume is unsafe is if you remove your cans and detech a ringing in your ears.

well, this is exactly why you perhaps should take the time to read at least the last couple of posts of this long (actually only 4 pages) thread...
Quote:

Originally Posted by Albatross05 /img/forum/go_quote.gif Hearing damage with headphones occurs because you are exposed to a certain level of noise for extended periods. Therefore, damaging levels will not necessarily even be the slightest bit uncomfortable. If you are thinking that you're not damaging your hearing just because you don't feel any discomfort, think again. You might not be but it's not a sure bet.

furthermore this idea has been refuted throughout this long thread

PS: not to be a know-it-all or to flame you, but if you do not bother to read any of the previous posts, why even bother to post in that thread? Really not to attack you, but this is a serious subject and I wouldn't want such a statement ruin someone else's ears

 

[stevenjchang]

my ears are BLEEDING!