Source: Tom's Guide US | Keywords: decibels, noise, canceling | Themes: Audio/Video Players
7. Phones At Home
If you’ve ever worked in a wood or metal shop, you’re familiar with ear protection. In the photo here, you can see a pair of AOSafety earmuffs I picked up last week at Lowe’s for $14.99. Howard Leight, 3M, and many others make similar earmuffs for about the same price. They’re light, comfortable, and offer a noise reduction rating (NNR) of 23 dB. Sure enough, when I slipped these on, everything around me seemed to recede to a distant hush. So nice—passive noise cancellation on the cheap. I cranked up the lawn mower, put these bad boys on, and it was downright relaxing...except for the mowing part.
You can buy AM/FM radio earmuffs for about $60, but radio commercials stress me out more than noise. I want my music and audiobooks. Stepping up to something like the Peltor Digital Worktunes will get you an NNR of 26 dB with integrated headphones featuring an 82 dB output limit. But these hogs weigh almost 20 ounces and cost about $90. Forget that. You can make a pair of NNR 23 dB passive noise canceling analog/digital-compatible headphones for a fraction of the price. All we are going to do is add materials to block sound from entering the ear canals to create home-made headphones that implement passive noise cancelation.
For this experiment, I sacrificed my son’s $15 Philips HS500 behind-the-head phones. You’ll see why in a second, but I strongly advise “clip-on” or “ear clip” headphones for this venture. The Koss KSC75 ($15 to $20) would be excellent here if you have a few extra dollars to contribute. But most of us have a pair of old, cheap headphones laying around. If you do, and you already own ear protection, then you can probably get through this project for free.
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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.