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That is correct. and √10 louder than 85 decibels.
Hi, it is a very interesting post which should be more popular. I've recently read an article in which the author deals with the problem of "super-high" frequencies and "super-low" frequencies : http://people.xiph.org/~xiphmont/demo/neil-young.html#toc_intro
To be quick, he says that listening to very high and very low frequencies can damage your ears without your noticing it when they're really too loud. That's what I understood...pardon my english as I'm French ^^
Anything loud (>85 dB) will cause hearing loss if you're exposed to it for long durations. Period.
Saying that headphones/IEMs will cause it faster doesn't make sense.
I'm coming in really late here - just found the thread after a Google search on the topic.
The reason for my search was that I tried using my smartphone with a sound meter app to get a vague sense of listening levels and my listening levels peak at are around 70dB when I tested using my HD650s (smartphone held with mic inlet right at the driver inside one of the cups) and also with my Re272s (one IEM held right up to the mic inlet).
The strange thing was that when I measured with my Shure SE535s (with Sony hybrid tips), the SPL shot up to 80dB+. I think it's because the outlet size is small enough that it made more of a seal against the mody of the phone.
This has me wondering - by sealing the ear canal, does an IEM create more pressure in the canal and therefore potentially more damage? Of course the ear anatomy is vastly different to the mic in my smartphone, but I'd be interested to hear people's thoughts.
SPL is just that, sound pressure level. Two headphones/iems will create the same pressure if they produce the same SPL.
But, if you measure them at different distances, then obviously the SPL will change.
Since you're measuring the SPL with your phone, I cannot rule out the possibility of a faulty measurement, or maybe the IEM was too close to the mic, while the headphone wasn't.
i think its cause you didn't close the gap between your smartphone and the earcup. i tried mine (HD558) by just placing the smartphone mic in the earcup and i got 55 db but when i sealed it with my palm went up to 65db. did you manage to get a seal on the Re272? cause seal will make a great difference to sound pressure (which is what is measured in db)
Makes sense. That's scary then. I've been listening a little too loud and I thought I was being careful. One of the issues with sensitive IEMs I guess - even at <25% volume, my T1 amp drives the SE535s to 80dB plus.
In other words, I think the SE535 reading was accurate while the RE272 was not because the sound outlet on the RE272 is so much broader I couldn't get a seal to the mic inlet on the phone.
well an amp meant for a 600 ohm T1 should be able to drive your IEM (about 8-16 ohm i think....? not sure) to insane self/anyone destructive volumes.
so the reading for the RE272 at 70db is how loud it sounds if you have it only dangling in your ear without a seal. the SE535 reading is how loud it will be if you got a seal on it.
also if you reading averages to 80 and below it should be okay. cause sound damage starts at 85db @ 10 hours, 90db @ 2 hours , etc until about 110db @ 5 seconds
but just for the heck of safety keeping it at 70-75 should be a good idea. afterall the accuracy of the smartphone is rather questionable.
Yes...i think the loudness war will also speed up the process
Oh, by T1 I meant Tralucent T1 model amp, but same same - your comments are still very helpful!
Apparently, they may. Especially IEMs. You guys should have a look at this publication (http://www.aes.org/e-lib/browse.cfm?elib=15786). Basically it states that when sound waves get trapped in sealed ear canal, air pressure builds up inside and can boost the signal even up to 50dB! This leads to ear drum excursions up to 1000 times greater than in normal listening conditions. That's pretty scary to say the least. To make things worse, this build up triggers Stapedius reflex, which makes you perceive the loudness much lower than it actually is. This publication is pretty new and I really hope that more proper studies will be made in the near future regarding IEM safety, because now it looks like we still know very little.
is this a threat with open backed full size headphones too?
No, there's only a "problem" with in-ear headphones that completely seal the ear canal and don't let any pressure escape.
The 50 dB boost, quite frankly, is a bit ridiculous. Of course you'll lose a lot of bass if you break the seal of an in-ear headphone. But there's no boost on top of the sealed frequency response. That's like saying that an open full-size headphone boosts the bass by 50 dB if you take it from the desk and put it on your head, but omitting the part with the desk.
Yeah, it seems a bit extreme and we don't know how the test was conducted (i.e. single frequencies, pink noise, etc.) There is so much constructive and destructive interference in music that it's hard to know exactly what is being measured.
That said, I have noticed that my tympanic/stapedius reflex does get triggered by certain IEMs even at low volumes, but I thought is was in relation to higher frequencies - maybe that part's just in my head!?
Thinking it though logically:
When you insert an IEM while switched off there should be normal pressure within the ear
When you play music through the IEM, each sound is created by positive and negative fluctuations in pressure
In a perfect situation these fluctuations balance out and return to "normal" pressure
Only in the event that we create a standing wave (i.e. reflected pressure peaks - positive and negative - building on top of one another) should there be any amplification of sound - much like placing a speaker in a corner and getting extra boomy bass
I would have thought that the irregularities of music, the soft, spongy nature of tissues in the ear, and the movement of the ear drum combined would limit or negate standing waves
Will have to keep on top of this and will definitely be using my IEMs at slightly lower volume now
I'd say if IEMs tend to create greater pressure, you'll be able to feel it, won't you?
Now, an 85dB SPL sound wave played by a speaker, compared to that played by the IEM may differ once it enters the ear canal, but I think the ultimate factor is whats the pressure created on the eardrum.