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Old 01-29-2017, 06:53 AM
LSLGuy LSLGuy is offline
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Join Date: Sep 2003
Location: Southeast Florida USA
Posts: 19,690
Sounds with very complex waveforms seem to be harder for humans to directionally track. Likewise intermittent sounds if they're real short. It seems as if the direction-finding algorithm starts over for each burst of sound.

I discovered this effect through an annoying experiment. Years ago in the service I worked in an open plan office space about 20x40 feet with 8 people at big traditional Steelcase desks. No cubicles, sound deadening walls, etc.

We each had a traditional 1960s style multi-line telephone with a traditional mechanical ringer on it. Often people were not at their desks and their phone would ring. There were 5 different departments spread across the 8 desks so not everybody had the same phone numbers appearing on their phone. When an unoccupied desk's phone rang on a number you didn't have on your phone, which they did every few minutes all day long, you had to jump up and hustle over there to pick it up and take a message. Leaving it to ring unanswered was simply Not Done.

It was effortless to direction-find the ringing desk(s). It rang, you looked up and knew which desk it was instantly.

Then the base got a "modern" Centrex phone system whose single line phones all had electronic ringers. They programmed the Centrex to ring the same primary number as before on each desk and left all the fancier features blank.

When one of those warbling twittering electronic ringers went off at another desk it was flat impossible to know where the sound was coming from. And we were all young and still had good high frequency hearing. Didn't help. You just couldn't home in on the noise; each twitter came from here, there, and everywhere. Just as your brain started to converge the ring paused, only to start over a second or two later. It was the same mental impression as a word "on the tip of your tongue". You know you've almost got it, but you have no insight into what that approximate solution is.

This was annoying as hell. After a couple weeks of all of us bitching about it and lots of calls getting answered late or not at all while somebody played Chinese firedrill running around the room hunting the ringing phone, we'd had enough. I knew a bit about Centrex programming and called the commo department. I got a sympathetic tech on the line who appreciated that I spoke phone. A couple minutes later we had appropriate hunt groups for the related desks and a pick group for all the phones. Office life got much better after that.

I really wonder why Bell Labs (as they then still were) ever settled on that noise for a ringer? It was utterly unsuitable for its mission.

Last edited by LSLGuy; 01-29-2017 at 06:54 AM.