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jackinnj 25th September 2012 03:49 PM

What deafness tells us about listening
I have BBC in the car sat radio -- interesting bit on cochlear implants this morning -- what struck me was that once a person becomes deaf, the tactile sense of low frequency energy through the skin becomes greatly augmented.

When I did the tests of PSRR for the regulator article in Linear Audio, there did seem to be some correlation in the low frequency part of the spectrum to perceived regulator "pleasantness". I am going to have to tease this out with a different spec analyzer like my dusty SR785 which goes well below the frequency of what we normally deem "hearable"

M Gregg 26th September 2012 10:08 AM

Its is a fact,

That low frequency sound is more than just hearing..
I'll give an example,

I was working in a area that had large cooling fans by the side of a room there was a low level (quiet) woof woof woof sound I could hear..I thought about the sound so used hearing protection foam ear plugs and ear muffs on top of my ears.. I started work on the commissioning of a data acquisition system..

After about two hours I began to feel dizzy and sick...I left the area thinking I had some kind of food poisoning...after about an hour the feeling went away so I returned to the room and started work again..within a short time about 45 minutes I began to feel very ill so I left the area again and went home "sick" one of my colleagues went to carry on with the work that had to be completed by the next morning..he used no hearing protection and after an hour started vomiting...he went home...

We refused to complete the work unless they turned off the fans on the cooling towers..the work was delayed until the week end shut down.

I still find it hard to believe that the hearing protection did not stop the effect...

M. Gregg

Charles Darwin 26th September 2012 10:31 AM

"I still find it hard to believe that the hearing protection did not stop the effect..."

I don't find that hard to believe at all.

Elephants use infrasound for long-distance communication which they receive through their feet. If you see an elephant standing still with one foot on tippy toes he is 'listening' to something.

And headphones are largely unsatisfying to listen to because in the bass the felt component is missing. Which is also why it is so difficult to get decent mixes together using them. It takes a lot of practice getting used to hearing and judging bass without feeling it.

M Gregg 26th September 2012 11:02 AM

It was interesting,

the low level (Bass woof) sound could not be heard outside the room, just the whistle of the fans. It seemed to be concentrated in the room.

The feeling was like travel sickness...nausea..dizzy...unable to concentrate on the job...and a feeling of " I want to get out of here!"

I wonder what the effect is on a pilot of a plane? The engine on some of the small single engined ones are very noisy? Perhaps the frequency is the important factor...

M. Gregg

Charles Darwin 26th September 2012 11:31 AM

Suppose the effect depends on the intensity of the infrasound.
That is to say that at low intensities as those a subwoofer is capable of it may well be pleasant but with large slow rotors the intensity may rise well above that and become deeply unpleasant as you have experienced.

I would suspect that airplane rotors are too small and turn too fast to get much infrasound out of them. Also planes tend to be outside where the sound dissipates quickly into the distance.

M Gregg 26th September 2012 04:09 PM

Regards Deafness,

I remember a guy many years ago, that would be at most of the rock discos and concerts I went to. He always had his head almost in the speakers on the stage...He liked it even better if they were right next to him...He would have a pint in one hand leaning on the stack with his head right up against the speaker grill.

I said to his mate hes going to make himself ill..his mate said its alright hes deaf but he can hear the music when its this loud and hes next to the speaker...:eek:

M. Gregg

Pano 29th September 2012 05:30 PM

Interesting. I was just listening to a lecture on this yesterday. Truck drivers and heavy equipment operators seem to be bothered by this, tho they rarely realize the cause.
Jack, interested to know what you find with the regulators. I remember the graphs and some lack of correlation between "measures great" and "sounds pleasant".

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