Path: utzoo!telecom-request Date: Thu, 2 May 91 0:07:17 CDT From: TELECOM Moderator Newsgroups: comp.dcom.telecom Subject: Why the Cotton Ball is There Message-ID: Organization: TELECOM Digest Sender: Telecom@eecs.nwu.edu Approved: Telecom@eecs.nwu.edu X-Submissions-To: telecom@eecs.nwu.edu X-Administrivia-To: telecom-request@eecs.nwu.edu X-Telecom-Digest: Volume 11, Issue 323, Message 1 of 11 Lines: 119 The question was: In article mcmahan@netcom.com (Dave McMahan) writes: > I have been asked why standard desk top telephones have a cotton ball > stuffed into the handset. Unscrewing the earpiece (not the microphone) > gives access to this little wonder. > Why is it there? The answers came from many of you. Here is a random sampling, and my thanks to all who wrote, even if you are not included below: From: Perry Stokes Subject: Re: Tele-Trivia: Why Cotton Balls in Handsets?? Date: 1 May 91 10:41:34 GMT Organization: The Free Software Foundation That is there for acoustic purposes , it helps keep the sound from traveling up to the earpiece. To understand what I mean, pull out the cotton and see if you can notice the difference. From: Jeff Bogart Date: 1 May 91 14:29:47 GMT The cotton balls suppress sound from the earpiece so that it does not feed back into the mouthpiece. Some feedback is necessary and most is controlled internally in the "network" (the little block with screws all over it). Try a four-wire phone for a wierd sensation - no audible feedback as you speak! From: Daniel A Margolis Date: Wed, 1 May 91 10:42:07 EDT Well I don't know if this is the "real" reason, but I think it's to keep the wires from rattling around. I have a handset with no cotton, and it makes a lot of noise. From: Gordon D Woods Date: Wed, 1 May 91 12:16:17 EDT Organization: AT&T Bell Laboratories > Why is it there? To reduce acousticly generated sidetone. From: Chris Petrilli Date: 1 May 91 16:59:20 GMT Organization: Free Software Foundation The reason, I believe is that in conventional phones (i.e. those with carbon mikes) such as the Western Electric models sold by the Bell companies, the receiver is hollow, and without the cotton ball (or something else to absorb sound energy) you would get feedback from the ear piece to the mike. None of the "new" phones I have have this "feature", but the old Western Electric on the wall in the kitchen (which, BTW, has been there for 25 years and still works wonderfully, as long as you hit it once in a while to keep the carbon mike working correctly) does have the cotton ball "feature". From: John Higdon Organization: Green Hills and Cows Date: Wed, 1 May 91 10:01 PDT You may be disappointed at the low tech reason. The hollow handset forms an accoustic chamber behind the earpiece, which you will notice is open in the rear. This is not unlike a speaker enclosure. Just as you will notice that most speaker enclosures contain fiberglas or some other sound dampening material, the cotton in the handset is there for the same reason. Experiment: remove the cotton. You will notice an inferior, "peaky" sound on your calls. Replace the cotton and you will notice an improved, "flat" response. From: Mike Berger Date: Wed, 1 May 1991 18:48:30 GMT > Why is it there? Probably for the same reason aspirin bottles are stuffed with cotton: To keep it from rattling around. The wire running through the handset will stay in one place but can still be removed or replaced if necessary. From: Kurt Freiberger Date: 1 May 91 20:35:29 GMT Organization: Computer Science Department, Texas A&M University Well, they had to put it SOMEwhere!!!! 8-} Seriously, though, I believe that it is an attempt to reduce the feedback via that nice conduit from the earpiece to the microphone. The hybrid gives the proper level and they wouldn't want to rely on the acoustics. Cheers. [Moderator's Note: So it was either done to help with the accoustics or to serve as a strain relief for the wire inside. Take your pick. Or as Kurt says, they had to put it somewhere! Again, thanks to all who wrote. PAT]