Loud Music Sucks!

Tyll Hertsens's picture

By now, most folks are aware of the potential for hearing loss by playing music too loud on headphones. I won’t bother you with that yet again. I’m going to try to take another approach. If you are turning the volume up to loud levels, you’re just throwing all that money you spent on great sound out the window. Here’s why.

The Acoustic Reflex
Your listening system has built in protection from loud noise called the acoustic reflex (also called the stapedius reflex). When you are exposed to loud sounds, small muscles (stapedius and tensor tympani) in your middle ear tense to increase the mechanical impedance of the system of small bones (oscicles) that move vibrations from your eardrum to your inner ear. The net result is a reduction in amplitude of sound being transmitted into the inner ear of up to 20dB at low frequencies, with less attenuation as frequency rises up to about 2kHz where no attenuation is seen.


Fig 1. The blue trace shows the attenuation in humans caused by the acoustic reflex. (This graph is from a paper called "Active Control of Ultrasonic Hearing in Frogs".)

The acoustic reflex is actually most active in reducing the sound level of your own voice. (In fact, birds and frogs have a very strong acoustic reflex to reduce the sound of their own calls.) If you shout “HEY!” and you’re very observant, you will notice that you hear a burst of low frequency noise in your ears. This is the sound of the muscles “firing” as they tense to reduce sound transmission. Because the muscles are directly attached to the bones of the middle ear, you can hear them as they do their work. Though this is a reflex, you can consciously tighten these muscles (it’s rather like raising one eyebrow in that it may take some practice) and observe this noise.

I tried to find references of how loud this self-generated muscle noise is to no avail, so I called Mead Killion of Etymotic to get his input. We had a lovely talk, but he also was unaware of any citation that might shed light on this muscle noise, but agreed that it was certainly there and was easily audible. I did a little experiment and played brown noise (like pink noise but less energy in the highs) and tried to level match it with my self-induced acoustic reflex noise. I came up with between 55-60dB SPL. That’s pretty loud.

I also carefully listened for a shift in frequency response, and sure enough I could easily hear a shift in emphasis to the higher frequencies. It made the brown noise quite a bit more pink sounding. Cool.

Generally speaking, the acoustic reflex kicks in at about 85dB SPL for single frequency tones, but may activate as low as 75dB SPL for broadband sounds like pink noise or music. I was surprised to hear the number was that low; 75dB SPL is about what I would consider a solid, but not loud, listening level. My normal listening level is about 70dB SPL, and I think most would consider that a fairly modest level.

Armed with the above information, let’s walk into a demo room at a trade show playing their system at 85dB SPL. Within about 100mSec --- way before you take your seat in the sweet spot --- your acoustic reflex kicks in. With 55dB SPL self-generated noise from the muscles now tensing in your ears, and a 20dB attenuation to the lower half of the audible spectrum, the signal to noise ratio drops to a miserable 10dB in the lows and some mids, and will appear to have a significantly tipped-up frequency response.

Have you ever noticed how audio systems tend to sound bright at a trade shows? I suspect it’s because they’re all being played too loud and your ears are changing things.

Here’s the bottom line: if you want to get your moneys worth out of your headphones, don’t turn them up too loud. I know it may feel like they sound better, but that’s just because your getting stimulated by the sound. Mead Killion said it on the phone to me, “If you listen carefully, you’ll find that loud music just sounds worse.”

Resources
Wikipedia’s citation on Acoustic Reflex --- In reading a lot of academic papers for this article I found that the Wiki citation is generally good, but a little misleading in spots.
Here’s a great general information page on Human Hearing.
Lastly, Etymotic makes earplugs that attenuate all frequencies evenly, check out their ETY-Plugs.

Share | |
Comments
dalethorn's picture
Hearing reflex

I read a scare story years ago about airbags in cars and how they would blow your eardrums out when suddenly inflated. Then sometime later, someone published a rebuttal that said with windows rolled up, you have a better chance of less damage because the airbag's pressure wave trips the ears' defense mechanisms more quickly than with the windows open. In any case, I have always disconnected airbags upon buying any new car. Note: I am inclined to distrust most data I see on the subject, since the insurance companies have a major stake in defending airbag use as a good compromise, economically speaking. Some unimpeachable data would be most welcome.

inarc's picture
Equal-loudness contours

Since the equal-loudness contours (ISO 226:2003) were empirically derived, why don't they reflect this phenomenon? The low frequencies flatten with increasing sound pressure while the change in higher frequencies is marginal.

Tyll Hertsens's picture
That's a very good question ...
... and I don't know.

It's possible, I suppose, that because the Fletcher-Munson curves are subjectively derived that ones sense of loudness might include bone-conducted information and a sense of how intense the acoustic reflex is within oneself in addition to information coming through the oval window of the cochlea. Dunno?

Great question, though, thanks for that. I'll keep it in mind, and see if I can't find out. Or perhaps someone will come along and provide an answer.

donunus's picture
Music Volume

Guilty of Rockin out to Loud Tunes! But I realized that i actually listen to Music at lower volumes than the typical non-audiophile rockin out. In Fact, I can't stand loud TVs, loud computer speakers, or anything that is too loud for its quality level hehehe. I turn up the volume of my cans just so that the mids become clear and intelligible without unnecessary screeching or distortion Smile There are just some speakers/headphones that demand more volume than others like senn hd600s for instance needing more dB in SPL to sound live than Grados for example which become screechy at levels where the bass isn't even natural sounding yet Smile

maverickronin's picture
For the Birds

"In fact, birds and frogs have a very strong acoustic reflex to reduce the sound of their own calls"

Which is the only possible way my parrot can keep her hearing. I've measured her at more than 105dB at about two feet...

svyr's picture
is there anything in the

is there anything in the study to suggest you get used to the sound level and the muscles gradually relax? (at least for relatively lower levels?)

Tyll Hertsens's picture
I was looking ..
... but didn't find that info in particular. There is a thing called the "acoustic reflex decay" which measures the relaxation of the reflex over time, but it's done over a period of 10 seconds only.

Here's a page about the history and overview of "The Acoustic Reflex in Diagnostic Audiology." Most of the information out there about the acoustic reflex is relative to using a tympanometer to diagnose various deseases. Here's an operating manual for a tympanometer, it's got some info in there about acoustic reflex decay and shows some data.

dalethorn's picture
Muscle relaxants

A lot of the body's autonomic processes can be controlled or modified indirectly through practice. You could make the hearing less sensitive (not good), or you could teach your ears to "clip" volume peaks better (but that's pure speculation). So if you just teach your ears/brain to relax *per session* to allow louder overall volume without any peak clipping, what happens when a peak comes along that's OK at the lower volume but not OK at the louder volume?

LFF's picture
Loud music does suck!

Loud music sucks and so does loud playback. I usually set my playback to what I consider a little above normal. Once I get to that notch, I will notch it back by two just to be safe as I really value my hearing.

"Have you ever noticed how audio systems tend to sound bright at a trade shows? I suspect it’s because they’re all being played too loud and your ears are changing things."

It could also be that they prefer a bright presentation so that people notice how "revealing" or how "high resolution" their systems are. It could also be crappy mastering.

PS: Nice picture...

KikassAssassin's picture
Measuring headphone volume

Do you have any suggestions for a (preferably simple and inexpensive) way to measure the volume of your headphones? I'm not sure how good a judge of volume I am, and I'd like to make sure I'm not listening to my music too loud and potentially damaging my hearing.

Amazon sells some pretty cheap sound level meters, but I'm not sure how practical it would be to use one of those with a headphone. I have a pair of Sennheiser HD595's, which seems like it might be large enough to fit a microphone in the ear cup, but I'd like to hear your thoughts on it if you have any.

Tyll Hertsens's picture
Super question!
And I've been thinking a lot about this one for a long time ... but haven't investigated it ... yet. I think you might have to put a hole in a piece of cardboard and push it up agains the headphones and then place the mike in the hole to measure. I will work on this one of these days, though. I'm also thinking you could use a SPL meter app in an iPhone and do it that way. Thanks for the comment, I'll work on it.
Grahame's picture
This is how I did it a while
Tyll Hertsens's picture
Great link ...
... thanks Graham. I thought I remembered someone doing it some time ago. Thanks for the link.
KikassAssassin's picture
85db is LOUD

I just got a sound level meter and set it up to measure the volume of my headphones. Apparently the volume I tend to listen to my music at is about 65-70db for a loud, heavy song. I saw a very short peak of 75db, but it stayed below 70 otherwise. I just turned up the volume (with the headphones NOT on my head) until the meter read 85db. I was almost afraid to put them up to my ears because I could hear the music clearly with the headphones sitting in my lap, but I put them up to my ear for just a second to hear how loud it was, and WOW. People gotta be crazy to listen to music that loud. No wonder it can damage your ears. I also see what you mean about loud music not sounding as good. I only left the headphones up to my ears for a second, but what I heard sounded terrible.

(This is apparently the point where I've officially become an old man and start complaining about those damn kids and their loud music Wink