Noise Cancel....

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Hi all,

I have a Q that i like from you to help me about:

My friend asked me for a portable device that cancel the noise around
him while it amplifies his voice only. Actually, he wants to utilize
his time reading in the bus, instead of wasting it. He refused the
idea of mp3 player because he could not focus in reading while any
noise is a round him even if it is a music. So anyone is aware of a
product that can satisfy his needs.

Thanx in advance for all of you..!

Archived from groups: rec.audio.pro (More info?)

Whilst Phil's suggestion is no doubt effective, you may be interested in
some ideas that don't carry the risk of being arrested...

Noise cancelling headphones (RRP)
Sony MDR-NC20 $180
Sony MDR-NC11 $150
Sony MDR-G94NC $70
Panasonic RP-HC70 $50
Panasonic RP-HC50 $40
Bose QuietComfort 2 $299

Chris

--
The voice of ignorance speaks loud and long,
but the words of the wise are quiet and few.
--

Archived from groups: rec.audio.pro (More info?)

tobe_better@hotmail.com (moon) wrote:

> My friend asked me for a portable device that cancel the noise around
> him while it amplifies his voice only. Actually, he wants to utilize
> his time reading in the bus, instead of wasting it. He refused the
> idea of mp3 player because he could not focus in reading while any
> noise is a round him even if it is a music. So anyone is aware of a
> product that can satisfy his needs.

Sure--there are "noise-canceling headphones" available in all price
ranges from about $25 to ten times as much. They use a microphone (or
sometimes a pair of microphones) built into the headphones to sense
the ambient sound, then this signal is amplified and fed back to the
headphones in inverse polarity so as to cancel the incoming energy
instead of reinforcing it. That signal can be combined with anything
else (music, etc.) that a person may want to hear, or else it can
simply cancel out sound from the immediate enivronment.

In practice this approach can reduce low-frequency part of ambient
sound to a useful degree, but even in the best of these headphones it
doesn't cancel out the sound around the listener entirely. I've used
headphones like this on train and airplane trips--they've reduced the
fatigue from the continual rumble.

But the most distracting sounds are often in the midrange of human
hearing, where noise cancellation of this kind is far less effective
than it is at low frequencies. So a good pair of earplugs can be worn
at the same time, since your friend isn't interested in listening to
other material.

By the way, your friend is very smart to make that choice, since in a
noisy environment it's nearly impossible to guess how loudly you're
playing anything. Trying to hear something clearly, it's very easy to
overamplify and damage one's hearing without realizing it until later.

--best regards

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moon <tobe_better@hotmail.com> wrote:
>
>My friend asked me for a portable device that cancel the noise around
>him while it amplifies his voice only. Actually, he wants to utilize
>his time reading in the bus, instead of wasting it. He refused the
>idea of mp3 player because he could not focus in reading while any
>noise is a round him even if it is a music. So anyone is aware of a
>product that can satisfy his needs.

He is looking for _headphones_ that cancel outside sound, so he can listen
to music, or he is looking for _microphones_ that cancel outside sound so
he can record his voice while he reads?
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

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Laurence Payne <l@laurenceDELETEpayne.freeserve.co.uk> wrote:
>On Mon, 11 Oct 2004 11:11:31 +0100, Chris Whealy wrote:
>>Whilst Phil's suggestion is no doubt effective, you may be interested in
>>some ideas that don't carry the risk of being arrested...
>>
>>Noise cancelling headphones (RRP)
>>Sony MDR-NC20 $180
>>Sony MDR-NC11 $150
>>Sony MDR-G94NC $70
>>Panasonic RP-HC70 $50
>>Panasonic RP-HC50 $40
>>Bose QuietComfort 2 $299
>
>But he doesn't want to listen to music. Without input, how are these
>different to ear-plugs?

On some noises, they are more effective than earplugs. On other noises
(higher frequency nonrepetitive noises) they aren't as effective as
earplugs.

Sennheiser also makes some nice ones, by the way.

>What's this about hearing his own voice? Does he want to talk to
>himself? In this case, he's probably uneducable. Why bother to
>read? :-)

That's why I was wondering if he really wanted to record himself
reading and the issue was a microphone and not headphones.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

Archived from groups: rec.audio.pro (More info?)

What the OP really needs is a Fenton Silencer.

Peace,
Paul

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mrivers@d-and-d.com (Mike Rivers) wrote in message news:<znr1097500366k@trad>...
> In article <e6a68193.0410110251.4a9703b0@posting.google.com> DSatz@msn.com writes:
>
> > Sure--there are "noise-canceling headphones" available in all price
> > ranges from about $25 to ten times as much.
>
> > By the way, your friend is very smart to make that choice, since in a
> > noisy environment it's nearly impossible to guess how loudly you're
> > playing anything.
>
> One of the things that I like about using my noise-cancelling
> headphones on an airplane is that I find that I can listen to music or
> the in-flight movie at a lower volume than than without noise
> cancellation, so I figure that it's actually protecting my hearing and
> this probably contributes to the reduced fatigue.
>
> However, the way that this form of noise cancellation works is that it
> plays "opposite polarity" noise right into your ears at a level that's
> proportional to the ambient level that it's trying to cancel. While
> the SPL of the cancellation noise is limited to a few mousefarts, if
> you were to use them when, say, doing yard work with a
> gasoline-powered weed whacker while listening to your portable CD
> player, you might be pumping an annoyingly loud level into your ears.
>
> I suppose someone has measurements somewhere, most likely unpublished.

Mike, think of it this way:

With nothing covering your ears, the noise from the weed whacker comes
in at full volume. With passive protection, this HF noise and a small
amount of the LF noise is attenuated by the material covering your
ears. By adding an "anti-wave" inside the earcups, the net sum for the
treated frequencies is zero SPL, or close to it. Just like combining
two waveforms, out of polarity. So this type of system actually
*reduces* the noise that reaches your ears.

Karl Winkler
Lectrosonics, Inc.
http://www.lectrosonics.com

Archived from groups: rec.audio.pro (More info?)

mrivers@d-and-d.com (Mike Rivers) wrote in message news:<znr1097598936k@trad>...
> In article <82150ded.0410120618.2ccd513e@posting.google.com> karlwinkler66@yahoo.com writes:
>
> > Mike, think of it this way:
> >
> > With nothing covering your ears, the noise from the weed whacker comes
> > in at full volume. With passive protection, this HF noise and a small
> > amount of the LF noise is attenuated by the material covering your
> > ears. By adding an "anti-wave" inside the earcups, the net sum for the
> > treated frequencies is zero SPL, or close to it. Just like combining
> > two waveforms, out of polarity. So this type of system actually
> > *reduces* the noise that reaches your ears.
>
> That sounds good in theory, but somehow I suspect that the brain deals
> with two separate pressures rather than dealing with the vector some
> of them. I'd like to see some in-the-ear-canal measurements to
> convince me. Do you know if there are any in the Sennheiser lab
> notebooks somewhere (not that I expect to ever see them)?

I'm certain that such measurements exist, be they from Bose, Telex or
Sennheiser (mainly for the aviation headset products) although I agree
that we'll never see them...

Since the ears are essentially pressure transducers, I'm curious how
you think the two waves can be kept separated. At least within the
earcup/ear system, the noise is actually reduced in SPL in comparison
to outside the earcup.

Karl Winkler
Lectrosonics, Inc.
http://www.lectrosonics.com