[asterisk-users] noise cancelling headset vs handset

[Karl Fife]

SOME NOISE CANCELLING HEADSETS ARE EQUIVALENT QUALITY TO THE PHONE
HANDSET.  

NOISE CANCELLING HEADSETS ARE DIFFERENT THAN NOISE FILTERING HEADSETS.  

NOISE CANCELLING:
I have used several noise cancelling Headsets -- Formerly a GN
9120-FLEX, now a Jabra/GN 9350e.  Both used on the same a Polycom 650. 
Both noise cancelling headsets have multiple microphones.  Like any
ARRAY microphone, the system uses a DSP and timing delays between the
mics to determine WHERE the sound is coming from.  Sound from THIS
direction--good noise, sound form THAT general direction--bad noise.  

It's not like DOLBY, where an algorithmic NOISE MODEL deletes bad noise.
 We all know Dolby sucked. It simply scraped away (equalized) a narrow
band of spectrum that roughly correlated with tape HISS.  

A noise CANCELLING headset is somewhat similar to the Bose noise
cancelling headphones.  They're listening to the outside world, and
process the signal accordingly to make a truer reproduction.  They're
not DELETING anything, and yes, a quiet room is better. 

SO YES, if you're recording IVR prompts, you would be well served to do
it on a Polycom HDVoice phone, in a quiet place, WITH THE HANDSET, not
your headset, simply because the audio transducer (mic) on a Polycom
HDVoice phone is second to none, AND because the mic is closer to your
mouth creating a higher signal to noise ratio.  

For the real world however, In a blind taste-test/bake-off, callers
can't tell whether I'm using my Polycom handset or my Jabra/GN 9350e
(using g.711µ--have not tried it with g.722.  Test volunteers welcome).

For the record: GN/Jabra claims that the 9350 was designed to be used
with wideband audio codec’s, so even if the quality is determined to be
slightly inferior Polycom HDVoice handset (or the eventual Snom
KlarVoice handset), it will be far superior to any other headset made
today. 

NOISE FILTERING:
Some headsets, including some of the 9120 models, have noise 'filtering'
technology which is different than cancelling.  One model uses a long
narrow hollow tube to guide sound waves to the microphone which is up by
your EAR, it is NOT located at the tip of the boom as you'd expect.  The
function of the sound tube is to mechanically filter sounds that are
correlated with some psychoacoustic definition of 'noise'. Others use
electronic filters.  To Jay Ashworth’s point:  Yes, they suck.

I hope this helps
-Karl



On Fri, 15 Aug 2008 12:35:50 -0400, "Jay R. Ashworth" <jra at baylink.com>
said:
> On Fri, Aug 15, 2008 at 04:59:26AM -0700, Vikas wrote:
> > Observation: When the agents talk using the polycom 650 handset the
> > voice quality on the other end is much better compared to if they talk
> > using the plantronics noise cancelling headset. If you would like a
> > recorded phone call when a agent is taking using the headset vs when a
> > agent is talking using the polycom 650 handset let me know and I can
> > post a URL to the file under this thread.
> > 
> > Is this happening because they are using a noise cancelling headset.
> > It would seem reasonable to expect that the noise cancelling headset
> > is cancelling out some of the tones in the voice.
> 
> Correct: a noise cancelling headset is going to have substantially
> altered audio reproduction characteristics vs. a non-noise cancelling
> handset, partially because it's a headset, partially because it's noise
> cancelling, and partially because the Polycom desksets have
> substantially the best audio I have ever come across.
> 
> Cheers,
> -- jra
> -- 
> Jay R. Ashworth                   Baylink                     
> jra at baylink.com
> Designer                     The Things I Think                       RFC
> 2100
> Ashworth & Associates     http://baylink.pitas.com                    
> '87 e24
> St Petersburg FL USA      http://photo.imageinc.us             +1 727 647
> 1274
> 
> 	     Those who cast the vote decide nothing.
> 	     Those who count the vote decide everything.
> 	       -- (Josef Stalin)
> 
> _______________________________________________
> -- Bandwidth and Colocation Provided by http://www.api-digital.com --
> 
> AstriCon 2008 - September 22 - 25 Phoenix, Arizona
> Register Now: http://www.astricon.net
> 
> asterisk-users mailing list
> To UNSUBSCRIBE or update options visit:
>    http://lists.digium.com/mailman/listinfo/asterisk-users