On Thu, 02 May 2013 02:53:01 GMT, benj <email@example.com> wrote:
>My favorite whine has to do with electret mics. Time was (time for old- >timers reminisce magazine review) when AT&T spent a LOT of effort >perfecting telephones. Heavy. Indestructible. Totally sonically tweaked >for intelligibility. You couldn't kill one and you actually could >understand the person on the other end...pretty much no matter what.
You have a short memory. The old AT&T (Western Electric) were solidly built, but could still be killed. The dials required lubrication every few years. The carbon mics would "pack". I had to pound them on the table before talking. It was standard practice for carbon dispatch microphone to be banged on the table before transmitting. Some also sucked enough current that they got warm. The old telco handsets were made from bakelite, which is durable, but also expensive. If I tried to manufacture a WE model 500 phone today, it would probably need to sell for over $200, mostly due to the high labor content.
>Then all of a sudden all of what I call "real phones" disappeared and >cheap plastic versions with electret mics appeared. Now you'd THINK that >a nice wide band electret mic would sound better. And at first it does. >But soon they all seem to develop a severe case of overload distortion >and it makes conversations all guesswork.
It's not overload distortion, whatever that means. Some electret mic capsules simply lose their charge. Basically, an electret mic is a condenser (capacitor) microphone, without the external power supply to charge the condenser. If the charge partially leaks away, the mic will sound awful. I don't think you can proclaim all such electret mics to be defective. Of the huge number of electret microphones I've seen in numerous radios, headsets, computer mics, and cell phones, I've identified maybe a half dozen as defective and easily replaced them. There may be a problem with some electret mics, but it's nowhere as bad as you make it seem.
>Oddly nobody seems to notice this problem!
True. That's because there is no problem.
>And it's not just my kitchen phone that looks like a banana >that does this, it's lots of large business systems. So you try to place >an order and all you get is mush. My doctor's phone is like that. I swear >I'm going to have to buy him a new phone so I can talk to him!
You might try cleaning out the wind screen in front of the electret capsule before buying a new phone. Saliva and dirt do a wonderful job of blocking the audio path.
>I remember even as a kid when my ears still worked well, the cop would >get a call on the police radio and all I'd hear is: >Razzafrazzasbuzzarumblebuzz, but the cop would somehow understand it all >perfectly and respond: "You bet! I'll be there in 15 minutes!" I'd be >amazed! "How does he DO that," I'd wonder?
That's different. Your hear needs to become accustomed to decoding the voice in the presence of noise. Anyone who uses a radio initially has the same problem. Actually, anyone who visits a foreign country also has a similar problem. Everything initially sounds like noise or garble. Extracting intelligence from the noise is difficult. Eventually, the human ear (and brain) adjusts, and the intelligence becomes much easier to extract. I had this problem when I switched from designing FM marine radios to HF SSB radios. I couldn't understand anyone talking on the HF radios. After a few weeks of listening to HF SSB, I couldn't understand anyone on the FM radios. Oh well. If you listen on the scanner long enough, you should eventually be able to extract the speech from the noise.