Slashdot Mirror
New Tech to Help Prevent Hearing Loss?
Wired is reporting that Blomberg is working on an invention to help users maintain a greater control over the volume output of portable music devices. Many people have expressed a growing concern about hearing loss in recent years due to the increased use of headphones and exposure to loud music. From the article: "Les Blomberg, executive director of the Noise Pollution Clearinghouse, described hearing loss with a nice analogy: 'If you have a field of grass and you walk on it, you compress the grass and it bends down over the night, and in a few days, it springs back up and is OK again. But if you keep doing that over and over, you wear a path in it. And that's kind of what happens with hearing loss.'"
Not a sound engineer, but a bassist. And I think I can provide the answer.
The solution we seek is what's known in the guitar world as a "compressor" or "limiter."
Fortunately, they are cheap and easy to build. What they do is put a ceiling on a range or ranges of frequency. I use it when I want punch in my high end but I don't want the thump in my low end to get out of control.
You can build the compressor to kick in and level anything (on all ranges) that exceeds the normal medically accepted maximum amplitude for human hearing.
The beautiful thing about compressors is that they stop you from producing obvious sounds you don't want but they don't simply reduce all sounds produced by your device.
What's so hard about this? And why in the hell are we calling this a "new tech?!" How about calling it "common sense?" If I ever designed a media player, this would be implemented regardless. The end user could look to find an amplifier if they want to blow their ears out, Apple has faced lawsuits and they will face even more as the millions who purchased their products use them and then deafly eye Jobs' deep pockets.
My work here is dung.
No, it's more complicated than that, and it's very important that you, you the reader, realize this.
You ears, like your eyes, adjust to the ambient level of sound. Your ears are only slighty better at telling you the absolute volume of a sound that your eyes are at telling you the absolute brightness of a room.
(You think you're good at that? Ha! Get a real light meter and prepare to be amazed.)
Unlike your eyes, which are at least decent at telling you when something is too bright, your ears suck at telling you when something is too loud. By the time they hurt, you're doing major damage to them. It's very easy to do minor, long-term, continuous damage to them, and since your ear will adjust to the ambient noise level, you'll have no way of knowing.
Mere volume control isn't enough. We need direct feedback about the actual volume level, as compared to the level that will damage our ears, because our bodies won't do that for us. We need options in our music players that say "never play a sound loud enough to hurt my ears", and if the ambient environment is too loud to hear the music over the max volume level it then allows, consider that a hint!
For that matter, we need this option in our cell phones too, implemented in hardware, not software. (Twice now my cellphone has played its "I'm dying, come plug me in!" sound while I'm talking to somebody. Both times I've wanted to throttle the designer.)
Agreed. Loudness is a subjective, relative quantity, while sound pressure level (which determines hearing damage) is an absolute. In a noisy environment, a given setting may not seem loud at all, while in reality the SPL is quite high. It is also worth noting that hearing damage is a function of both sound level (SPL) as well as exposure time -- a noise "dose". Turning up your favorite song to rock out for a few minutes may not harm your hearing in the least. Leaving the volume up for hours at a time, however, can be damaging, even at seemingly innocuous levels. For instance, OSHA limits worker noise exposure based on exposure time - 85 dB(A) is the limit for an 8-hour day, but much higher levels are allowed if exposure is shorter.
Ut Tensio, Sic Vis
Yeah, I had a very similar problem with my Palm. Solution? Get a separate inline volume control. Then turn the device volume up and turn the inline volume down. This effectively increases the impedence of the line, thus cutting out the noise. Voila! Also useful for crappy airline jacks or other places where they have stepped volume.
It's not about "volume" but "dynamic range".
If you have background noise of 40db (not uncommon in a car), then if you turn the volume up loud enough to hear the soft parts, the loud parts get blasted out.
Happens all the time on TV -- real noticable on Sci-Fi, where they compress program volume down so that the max-sound is at about 65% (numbers are guestimates based on experience) of the dynamic range of the medium. Then the advertisers come in and balance commercials with the minimum range set to about 30%, and the loud spots peg up near 95%.
On reputable stations, they will balance the average output to some fixed standard, but on cheap-stations like scifi, they downgrade the program signal so advertising gets boosted way beyond normal. My volume setting on Sci-Fi channel is about 10-15% higher for program segments than on other channels -- but when commercials come on, prepare to get blasted.
Same happens with music devices. Not only is there a wide dynamic range available on the device (the more expensive the device, usually the wider the dynamic range), but it's compounded by users having to crank up the volume to drown out background noise. That makes the loud sections *way* too loud.
I solve the problem on most of my pre-recorded stuff by normalizing everything (though not usually compressing, as compressing causes loss of fidelity). Same
problem happens on sound playback out of my computer. Play a video and sometimes I have to turn the volume up to 80% to hear anything, but play a WAV or some CD's, and they are already normalized to 98%. Ouch!