"Frequency Compression"

Would like quantitative Information of effectiveness of this technique !!

Fiddling a bit with hearing aide technology, I first was looking at human Frequency response which we discussed the other day being from 20hz to 20,000 hz and that, as we age, we lose at both ends but mostly at the high ends.

A quick test of mine was done using web.engr.uky.edu/~donohue/audio/fsear.html which runs from 40hz to 18,000hz and a quick test showed me limited to 100hz to 8,000hz.

And, from other papers, I learned that some hearing aides have “Frequency Compression” capability that takes those high frewuency sound that we can no longer hear and compresses them down into a range that we can hear.

Seemingly VERY NEW, an paper at What Is Frequency Compression in Hearing Aids? discusses it and then mentions some hearing aides that have that capability.

SEE BELOW and those very new “Phonak Audeo Paradise” (four different quality levels which I may have already sent you) have that compression.

Seems to me, if done right, they could bring those high female voices brought down into one’s hearing range and help over-weight those background noise levels that limit one’s hearing .

But, for certain, to work right the Audiologist would have to have the equipment and the knowledge to provide the proper level of compression so that one must find someone who has had training and can discuss any or all of the devices below and, after one is chosen, adjust them properly to one’s hearing capability.

NOTE: I suspect that many audiologists may not even know of the technology – even when they’re seeling the models below – nor will they have the equipment to properly set them up for each indvidual.

Frequency compression, frequency lowering, frequency shifting technology has been around for awhile.

I can not imagine people fitting hearings would not know about this technology in the particular hearing aid software they are using. Something I have noted is not all fitters want to use it or are hesitant to use it.

Many of us on this forum use this technology with great results.

1 Like

I’ve posted this before, but it’s kind of "An everything you’d want to know about frequency lowering and sorry you asked. :smile: "
https://web.ics.purdue.edu/~alexan14/fittingassistants.html

and to add: Although normal hearing goes up to 20khz, there is no speech information up that high and no benefit of trying to lower sounds that high. Lowering sounds does introduce distortion so it’s finding the proper balance. Many people do quite well hearing only up to 3khz and I doubt there’s much benefit for understanding speech to go much beyond 6khz if it needs to be done by frequency lowering.

1 Like

I use the Oticon Speech Rescue with great result. It’s very easy to set it up in one program and not have it in another program, then toggle back and forth between the 2 programs to do real time A to B comparison to see if it’s worth it or not. There’s nothing to lose to try it out.

And I agree with @Raudrive, the OP gives too little credit to hearing care providers and assumed incorrectly that many of them don’t know much about this technology. If they don’t mention it, it’s more likely that they may deem it unnecessary for a patient, depending on their hearing loss.

As has been pointed out in previous replies in this thread, what you’re referring to is commonly termed “frequency lowering” to distinguish from what is commonly called “frequency compression.” The latter is the technique of moving the extensive range of soft, moderate, and loud sounds a normal human ear can hear into the remaining much smaller and more narrow remaining range of relative hearing loudness that a hearing-deprived person typically has any remaining ability to hear.

MDB furnished a link to read more about frequency lowering. The Starkey Compression Handbook is a good reference for frequency compression of loudness (don’t remember if it treats frequency lowering). It’s been cited on this forum since 2013 but here’s a more recent up-to-date link.

I imagine if one searches on “frequency compression” or “frequency lowering” on the forum, you’ll end up with an overwhelming number of links but doing so is a good way to find out in advance how aware the forum is already of an idea.

That last post conflates level compression and frequency compression, which isn’t helpful.

As to the OP. You would need to find someone who lived under a rock for the last seven or eight years as an audiologist not to know about it.

Some fitting software puts it on automatically as part of the initial fitting and you have to turn it off by default.

It has potential for some people, but it requires some quite specific rehabilitation. The hearing aids don’t tend to sound natural to other people. Musicians tend to hate it too.

5 Likes

You’re right, @Um_bongo, but the saving grace is in the actual Starkey Compression Handbook , one would find that the term “level compression” gets a fair amount of discussion therein.

The second method of maintaining listening comfort has no official name, but has been
called mid-level or comfort-controlled compression (Byrne and Dillon, 1986). Figure 3-6
shows a sample I/O function of comfort controlled compression. The following are some
desirable characteristics of a circuit designed for this purpose.

But I guess I have been erroneously calling level compression “frequency compression” because the amount of loudness compression applied is a function of frequency.

“Amplification compression” might be a far better, clearer term to replace “level compression,” IMHO. But I have to learn and respect the accepted industry terms and not mislabel them. Thanks for setting me straight! I have corrected this post from an initial ill-considered reply to Um_bongo.

Yes I think Jim is talking about level compression which is a completely normal part of every hearing aid.

Frequency compression or lowering or shifting is completely different and is a long-available technology that moves speech frequencies above the individual’s personal hearing limit down into what they can still hear. It can be very successful but on the other hand not everyone, me for example, likes the unnatural sound that results. All audiologists know about it anyway. It’s hopeless for music.

Personally I think that if you can hear 1kHz to about 4 kHz ok, without your hearing aid being pushed into distortion and without feedback, then you should leave frequency compression behind as something that isn’t going to help you at all. (You also need to hear frequencies below 1kHz but frequency shifting/compression isn’t applicable there.)

1 Like

Ok, I’m not going to argue with your semantic interpretation of your answer, but the OP specifically referred to Frequency Compression.

There’s an easy rule to understanding this.

If the input frequency response is the same profile(give or take a couple of HZ) as the output response then there’s no Frequency Compression. If the output is ‘Bunched’ or ‘Squeezed’ into a specific zone, then it takes place. A frequency compression output will invariably occupy less space on the horizontal response scale, as you’re cutting the output bandwidth.

Conflating that with conventional compression which changes the amounts of gain at different input power levels is, like I said above, rather unhelpful.

1 Like

I apologize. You’re right, @Um_bongo. And I’ve corrected my initial reply to point that out.

2 Likes

4 posts were merged into an existing topic: Compression problems with Phonak Audéo M90 hearing aids

3 posts were merged into an existing topic: Compression problems with Phonak Audéo M90 hearing aids