I wonder if anyone has done tests using multiple tones well above audible range and at fairly high levels. Non linearities in the physical couplings in the middle and inner ear might produce IM products within the audible range or affect sounds within the audible range just as you describe.
In article , Grimly Curmudgeon scribeth thus
The only problem I have with hearing is in crowed pubs where I have great difficulty hearing ...
... "Isn't it your round"?....
Considering the amount of real world experience you must have had and time around .. thats quite good;)...
Search for Oohashi. (I think that is how his name is spelt.)
Slainte,
Jim
In article , Brian Gaff scribeth thus
Good modulator and tuner and FM is rather better then most perceive it to be;)...
Having spent a year on FM receivers, I can assure you the spec's don't reveal one tenth of what is going on.
In particular the width of the IF strip is hugely influential. And how the skirts work. As Brain surmises, various phase delays do horrible things to HF stereo stuff.
Don't suppose any of that time was spent with DSP at all?...
Didn't exist then mate.
"The Natural Philosopher" wrote
That would rather depend on what's in the specs!
Indeed, the IF bandwidth of an FM receiver is particularly critical in determining performance, particularly when carrying a stereo subcarrier. But it's perfectly possible to include information on the shape, width and phase performance of the IF passband in the specs. We don't need to get into "golden ear" stuff.
David.
It might be, but in the days when I was doing this,(1975) no one did.
In particular ceramic filters sounded pants.
I am sure things have changed since then, though.
We don't need to get into
Presumeably the effect that causes the dentist's ultrasound to be extremely offensive, combined with the waveform distorrtion that is caused by the asymmetrical impacts on the teeth. I ended up lowering the cleaning interval and insisting on an old fashioned cleaning.
Kind regards
Peter Larsen
We were somewhere around Barstow, on the edge of the desert, when the drugs began to take hold. I remember tony sayer saying something like:
Selective deafness is a curse and a blessing. I can detect with pin-sharp accuracy, "What's yours?" from the other side of the noisy crowded room.
.
FWIW Yamaha did once do FM tuners with 'active nulling' of the 19k pilot tone so their filters could be more relaxed about HF roll-away.
Indeed, as does limiting the transmission bandwidth.
Slainte,
Jim
Here if anybody wants a quick link:
But any IM products within audible range would surely be heard just like ordinary sounds or result in perceptible distortion to other signals within the audio range.
On a possibly related topic...I'm one of those people who, in the past, have been plagued by the mysterious "drone" that most cannot "hear". I haven't heard it since we moved house but it was real and quite location dependant although not directional. I know it wasn't actually audio because I couldn't measure or record it.
There was a "hum" which it seems a lot of people could hear in the mid
70's, sounded like a distant diesel engine though you could never quite work out which direction it was coming from. There where some articles in the papers for a while then all mention faded away...
Yes, that is the one. There were suggestions of tinnitus or other medical problems in the media but I'm convinced it was a real phenomena. The frustrating thing was that nobody else experienced it in/around our house. Since we moved I have never heard it.
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