"Ambient Deafness"

You know where you can't single out one stimulus from background noise?

I have this thing to some degree. Everyone thought I had a hearing problem while off sailing, because every other word people said seemed to get lost in the noise of the waves and the engine.

I don't have that problem when in a low noise environment, though.

Anything you can do to correct it??

 

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That's called bad hearing. It runs in my family (in the males) so I know what you're talking about. Hearing aids help.

 

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It's not bad hearing, though. It's not that I don't hear, it's that I take in auditory data but don't filter properly.

Hearing aids sound like a really really bad idea. I don't want to hear everything hyper loud.

 

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I know from firsthand experience the exact phenomenon you're referring to.

Consider the analogy of a man complaining of poor vision. "It's not that I don't see," the man says. "I take in visual data, but my eyes just don't filter it properly." It's plain to see that what the man is describing is the blurriness which is characteristic of run-of-the-mill poor vision.

Similarly, what you are describing is the very symptom of poor hearing. Because all sound is degraded equally to us, we don't have an objective standard of comparison for recognizing that sounds are unusually quiet or dull at all. This simply seems to be the volume at which the world presents itself to us -- just as a man who has never worn glasses may not realize that he has poor vision. (Incidentally this was nearly my exact experience with glasses.) But because we are receiving such degraded auditory info, it makes it much more difficult to pick apart, or "filter," the sound around us. It doesn't seem quiet; just indistinct. And that is the very phenomenon of poor hearing.

Fortunately that's not how hearing aids work. They work not by amplification but by compression, meaning that soft sounds are amplified while loud sounds are attenuated. I have only done a small amount of reading on how hearing aids use compression (I don't wear a hearing aid myself -- they are expensive), but it's likely that they use more sophisticated forms of compression even than what I have described. In short: they work well.

 

Ah...

I'll get it tested at some point, when I can be bothered...

What do hearing aids do though when all sounds are equal? If someone is talking at the same loudness level as an engine or wave, what would it do?

 

First I should point out that I'm no expert on hearing aids, so any advice I give on them should not be interpreted as anything other than an educated guess.

That said, I think the important point to consider in that situation is that the compression works in an absolute, as opposed to a relative, sense. This means that both sounds will probably be handled in the same way -- the important thing is not their relationship to each other but rather their absolute standing on an objective scale of intensity. If both sounds are equally quiet with respect to this scale, they will both be amplified equally, whereas if both are equally loud (as it sounds like would be the case in that scenario), they will both be attenuated equally. The two sounds will still be equal to each other in volume after the compression -- just as they would be for a non hearing impaired individual -- but they will now be in a range that is much easier for you to work with (i.e., much easier to hear).

To better understand compression, this is one of the few cases where it actually helps to visualize a sound wave. Here is a visual representation of an audio (WAV) file which illustrates compression:

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In this image, the green is the audio file before compression, and the red is the same audio file after compression. (The two different lines are channels -- the file is in stereo.) As you can see, quiet bits have been amplified greatly while louder bits have been either only slightly amplified or ignored altogether. This would be an example of upward compression, something I hinted at in the earlier post but didn't elaborate on. This is probably a more accurate account of how hearing aids process sound. Anyway, the quieter a section is, the more it is amplified. Even after compression, however, that section will still be quieter than other sections of the song, as it was before -- the point is that the difference in volume is much less than before.

 

It's not the loudness or quietness of them though, it's the fact that the one stimulus I'm trying to listen to is getting lost in the background.

For me to hear properly, the person talking has to be louder than every other stupid little stimulus. How would you manage that with a hearing aid?

 

I understand the issue and have already tried to explain both the source of the problem and how a hearing aid would help. I'd rather not talk in circles, so I'm afraid there's not much more for me to say on the matter.

 

The human voice operates over a certain set of frequencies. I'm pretty sure hearing aides can amplify certain frequencies and leave others untouched.

 

Oh right...

 

I know and I understood your post - I just didn't get how they could be

if the problem was not being able to single out only one of them.

Did you mean it would make the two sounds clearer and more distinct from each other?

 

It should, yes, by virtue of the two sounds being in a range that is easier for you to work with.

It may seem that the problem is that the two sounds are of equal volume. But this would also be true for non hearing impaired individuals, and they can distinguish between the sounds just fine. The problem is that, to us, the two sounds are in a in a range that is difficult to work with. That they happen to be equivalent in volume is somewhat problematic, but not any more so than it would be for someone with perfect hearing -- which makes it largely irrelevant.

Idle Mind also makes an excellent point that it may be that hearing aids preferentially amplify sounds that are within certain frequency ranges, particularly the range of the human voice. I do know that at least some hearing aids have the capability of working with certain frequencies -- as I read at some time that Jeff Beck wears custom made hearing aids that help him deal with the exact frequency of his tinnitus -- so it should have occurred to me that this technique might be common to all hearing aids. Or it might be a more "high-end" feature. I'm not really sure, but this is something worth looking into if you're considering a hearing aid.

 

I'm pretty sure your hearing will turn out to be quite normal. I mean, if you only noticed it with the wind blowing past your ears..
You might have some hearing damage from setting your iPod (or whatever) too loud, though.
If you are trying to concentrate on sailing a boat and the wind is blowing past your ears etc., it's perfectly normal that a few words get lost in the noise.

 

Background noise does cancel speech and other sounds if the intensity of the noise is higher than speech or that some of the noise is of the same wavelength as speech. The military has for years experimented with anti-noise. A system where sound is analyzed and an identical sound is generated, thus cancelling the sound and nothing is heard. That way their tanks and heavy armor can roll into place and not be heard. I myself use a system based on this to sleep. I put a fan by my bed for "white noise" thus allowing my kids as well as my grandkids to play right outside my door and not wake the old grump up...it works very well.

 

I should point out that there are several forms of central deafness (as the above condition is known), but they are all exceedingly rare. Certainly it's not the kind of thing I would trust to a self diagnosis (speaking to visceral_instinct here). Additionally, it's not the kind of thing that develops gradually -- it's either with you from birth or the result of brain trauma.

 

Did you have that test yet, Vis ?

 

@Enmos: Nah, it's not a big deal. Might go have it done sometime. It only presents itself if I'm trying to hear someone over background noise; it's only a minor thing.

@Dub: I have always had this thing. I assumed I just had shitty hearing.

@Trippy: That's interesting...I have that thing too where minor noises affect me. A ticking clock will keep me awake for hours, so will any inflammation in my ear, because I can hear my heartbeat.

I also mishear words, because I hear the pure data first and somehow fail to process for a few seconds. For example my mum can say to me 'Miss a line' when I'm typing something for her, and I hear the syllables 'miss a line' but don't process for a while, can't think what to interpret that as, and think 'Misalign? Why does she want me to misalign? Oh, wait...she meant *miss a line*.'

 

Ah ok. Well, if it doesn't hamper you in any way..

 

It really doesn't sound like an actual issue. Loosing words in a white noise environment is why they sell "wave" cds for people to listen to while they sleep. Also its not uncommon for people to find certain frequencies confusing, for example young people have trouble with low frequencies, men and older people have trouble with high frequencies, etc. If you find it seems to be increasing you might see a specialist, particularly if there are other symptoms, but I wouldn't worry about it other wise.

In particular a lot of people get congestion out on the water from the change in humidity (and the salt if is sea water) and that in and of itself could do it.