Source: Tom's Guide US | Keywords: decibels, noise, canceling | Themes: Audio/Video Players
2. Pump Up The Volume
Question: Can you do serious damage to your hearing with loud music?
Answer: Yes. Mom was right.
Despite the fact that Mom was a chain smoker whose key source of information on all matters was Larry King, there were a few health issues she called exactly right, even if she had no rational proof to back her positions. Loud music and hearing loss was one of them. But to know why she was right, we first have to back up and discuss the nature of loud sounds and the human ear.
As you probably know, sound is conveyed in pressure waves. When you stand near enough to exploding fireworks, you can feel the whump of the pressure wave crash into your body as you hear the detonation, right? Sound waves work like waves on water’s surface, expanding out from the point of origin. Small sounds make small waves; big sounds make big waves. When a speaker vibrates, it’s creating sound waves. Crank up the volume and the speaker’s surface will make bigger oscillations, thus producing larger sound waves.
Just as with water waves, sound waves weaken with distance. This leads to a lot of confusion since it’s meaningless to say something has a measurable loudness without also quantifying the distance from the source to the listener. Still, sound is generally measured in decibels (dB), a logarithmic measurement that conveys the power magnitude of (in this case) a sound wave versus a 0 dB reference level, which is the level at which sound ceases to be audible to the human ear. An increase of 10 dB represents a 10X change in power ratio, or a relative doubling of perceived loudness. Someone whispering 10 feet away might be 30 dB, but if the person steps back to 20 feet away, the same whispering might well be inaudible given that most people can’t hear anything below 10 dB.
A quiet environment is often described as 40 dB. Normal conversation hits around 60 dB, about the same as background music. A vacuum cleaner or noisy restaurant qualifies around 70 dB, as does loud conversation, which makes me think my kids, when happy, are good for about 80+ dB. Screaming kids actually produce about 90 dB. Measurements show a power mower ranking at 105 dB, although I know for a fact that my kids can be louder than a power mower, which proves that the human ear is more sensitive to certain sound frequencies than others. A typical night club qualifies at 110 dB.
Amplified rock music falls in the 110 to 130 dB category, occasionally topping out in the 140 dB range, which is kind of scary when you consider that physical pain sets in around 130 to 140 dB.
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One word: Google.
Gosh, we're not the general public... we're nerds
correction, physical pain doesn't set in at 130db, feeling sets in at about 130 db, so that bass that you feel thumping is above 130db, but since volume is a function of decibels and frequency it is very quiet. but children wailing is very high pitched so them at 80 db is significantly louder than the bass in your car. if you want to learn more than just do some more googling around. try searching "volume"
A clarification on ANC theory. There is no "anti-noise" generated. Ambient sounds strike the speaker cone moving it. Essentially the ANC signal applied to the diaphragm resists this motion of the cone, holding it still. Without movement the sound energy is dissipated as heat on the back surface of the cone. It is not canceled out in the classic sense, the compression and rarefaction of sound waves are mechanically destroyed.
One more really simple thing to add here. Put some really high-quality foam earplugs in your ear canal AND use your ANC headphones. This is what I do when I fly (Bose QC2's and custom-fit plugs). You've got to have enough sound without distortion in your headphones to overcome the attenuation of the plugs but for the most part their response curve is flat (if not a bit high on the low end). So your tinny-sounding earphones are actually going to have a bit more bass overall.
I've also been known to wear my Shure earbuds under my QC2's but they stick out far enough that I have to be careful not to touch them against the inside of the headphones. The nice bit is that even sitting in the back of an MD-80 I've only got to put my iPod at about 25% volume to hear every detail.
Shures with QC2 sounds like Heaven...assuming Heaven is a very quiet place. :-)
Regarding joeman42's comment, first, I'm going to say that I am definitely not a sound engineer nor any kind of other acoustic specialist, so the depth of my understanding may need improvement. However, the description I gave of ANC fits every description of the technology I've been exposed to over the years. For example, check this paper: http://doctord.dyndns.org:8000/Pubs/POTENT.htm, which describes the ANC process like so: "the noise is modeled to produce an anti-noise waveform at the output speaker." Given this guy's title as Vice President of R&D for Noise Cancellation Technologies, Inc. and the fact that this paper appeared in an IEEE publication, I'm pretty confident of the source.
Another very entertaining article from you.
“(Once again, you can tell something about the quality of a site’s content by the frequency of typos and errors in its text.)”
You might want to change that line before someone of bestofmedia knocks on your door and gives you a kick in the nuts when you open.
Another very entertaining article from you.“(Once again, you can tell something about the quality of a site’s content by the frequency of typos and errors in its text.)”You might want to change that line before someone of bestofmedia knocks on your door and gives you a kick in the nuts when you open.
Yeah, I can add that to the list of reasons I've given them. ;-) But really, you can tell the difference between a rushed schedule and borderline illiteracy or outright disregard for quality. If I've got to take one in the giggleberries for saying that Web sites in general need better quality control, so be it, but I think Bestof has a good crew that does good work. I'd rather have a few typos and solid reporting from people who care about the readers' best interests than a lot of the over-polished, under-thought dreck common in the field.
Thanks for the kind words.
Interesting article
I have hearing loss. I was born since birth, and therefore, I can't use headphones or go to rock concerts, lest I risk damage to my ears. I have never used an i Pod for more than a few minutes, and I'm glad.
I'm 15 years old, and I estimate that by the time I'm 40, my generation will have worse hearing than me. I'll be laughing "I HAD hearing loss BEFORE it was POPULAR!"
I should hope so.