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Artifacts after change to linear compression

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I use Signia Ax7s. I play classical guitar. when I first got the Signia the pre installed Musician Program was unusable for playing my instrument–way too many artifacts. But after some arm twisting my last Audi followed guidelines and turned off feedback management etc. Problem solved!

Three years later I sent my aids in under warranty for new batteries (and received brand new aids by the way!). While waiting for these to come in, my new audi programmed some loaners to my old settings. But he also moved them to a more linear compression–I hope I have that right–which is also recommended for musicians. However, I’m now once again hearing artifacts when I play my guitar. It’s not as bad as before, but it’s there. I now have my new/old aids back. Same issue.

Artifacts appeared after the new, linear compression was installed. is it possible that this has somehow caused the artifacts to reappear? Or maybe the compression amount needs to be adjusted? Sadly all of this had to be done on the fly–I got covid and couldn’t go into my audis office when my new/old aids came in; he merely once again entered the old programs and settings and off I went. I do have an appt. for tomorrow. Any insights/help?
There’s always the possibility that I’m not used to the linear compression–but that’s not it. I wore the loaners for four weeks. And artifacts are easily identifiable.

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I find that linear compression is less forgiving of an imperfect fit. Maybe what you’re hearing is some overly amplified frequencies? Can you have both programs available to compare them? With Oticon, that’s possible, and I’ve done it many times. I’ve realized that, for my hearing loss, some compression works great for my classical guitar but not as well for my acoustic guitar.

Edited
@e1405 said:

I find that linear compression is less forgiving of an imperfect fit. Maybe what you’re hearing is some overly amplified frequencies?

So…would changing to more linear compression change other aspects of my settings? What are they?
It’s hard to say–but my guitars sound muddier than before…
When I first started playing after this change it sounded like my guitar was louder and I turned down the volume of my aids. But even at lower volumes I’ll hear the artifacts.
i was good with the old compression! I do have TWO musician settings available. so yes, I can try the one on one comparison. Thanks for your quick response.
any other responses are welcome!

@jeffrey said:

So…would changing to more linear compression change other aspects of my settings? What are they?

No, I don’t think that’s the case—unless your hearing care professional has reset some of the digital features to their default settings. Another thing to consider is that fitting formulas often have different compression values across various frequency bands. When you switch to a linear setting, you lose that unique balance between the bands.

@jeffrey said:

When I first started playing after this change it sounded like my guitar was louder and I turned down the volume of my aids. But even at lower volumes I’ll hear the artifacts.

From my experience, linear compression doesn’t work well with classical guitars—it gives them a “dull” quality, just as you mentioned. It does sound good with acoustic guitars, but then it also leads to fatigue over time, so I guess I could say I use a semi-linear scheme now.

By ‘linear’ compression, I assume this thread is referring to volume levelling/limiting that’s applied equally right across the range of frequencies?
If I’m right, then that’s the opposite of multi-band compression, which the Audio can (and may routinely) set up, wherein a subset of probably eight frequencies are individually controlled. That might well be fine for speech, but does terrible things to music! Sort of sucking, phasey quality when there are numerous instruments playing. Been there: my lovely audiologist understood, and switched the obsolete Phonak M70s to linear (if that’s the term?) so now the music plays on, nicely enough, from CD or my piano.
We all hear differently of course, but my guess is that music is best served by what’s typical in a sound studio: compression slight or drastic, slow or fast, according to the effect aimed at, plus a rapid-acting peak limiter to prevent over recording. (Or in our scenario, pain when a plate is dropped!)

@ellisonvoice said:

By ‘linear’ compression, I assume this thread is referring to volume levelling/limiting that’s applied equally right across the range of frequencies?

I understand linear compression to mean a 1:1 ratio across soft, moderate, and loud sounds. Here is a good reference: The Compression Handbook - Fourth Edition. The screenshots below are from this reference.

image

image

In reply to @ellisonvoice

You can change the formula used when programming your to get something similar to “linear” etc so you can look at
compression as a way of making soft sounds louder and keeping loud sounds at a comfortable level, so linear would have a compression ratio of 1:1 which would mean that the gains for soft and loud inputs are the same as others ,this would be the old analogue signal hearing aids from yesteryear?

In reply to @e1405

Ohhh - thank you for that clarification. So I guess a non-ambiguous term might be wideband.
For further confusion, I was chatting with a couple of audiologists, recently qualified, who took compression to mean frequency comping, rather than dynamic. Eh?

Edited

In reply to @tenkan

@tenkan said:

his would be the old analogue signal hearing aids from yesteryear?

Yes, except that the digital aids will still compensate for a patient’s loss profile. Analog aids wouldn’t do that. i just had a discussion with my specialist about this. he added that since my loss was almost entirely conductive, linear compression shouldn’t be an issue in terms of sudden loud noises the way it might be for those with sensorineural loss. Lucky me! (conductive loss dissipates sound energy.)

And my artifacts issue is fixed!! it turned out to have nothing to do with the new linear compression. Instead, when my programs were installed in the aids sent back on three year battery warranty, they automatically rebooted wind and feedback suppression. Hence, my aids would sound great until something occurred to set off feedback suppression–and then the artifacts would kick in. and then go away! I doubted my sanity. It’s all good!! My specialist had it figured out before i arrived. phew!! easy peasy the fix took ten minutes and now I can really enjoy the linear compression.

@jeffrey said:

And my artifacts issue is fixed!! it turned out to have nothing to do with the new linear compression. Instead, when my programs were installed in the aids sent back on three year battery warranty, they automatically rebooted wind and feedback suppression.

Oh yeah this is a common theme actually, you’d think they would send them back to audiologist with the same settings or your audiologist would be sure to check that they match your stored session in the software before handing back, but great all good and sorted out in the end.

this topic drew some interest over on the Adult Musicians with Hearing Loss forum. here’s Marshal Chasin’s contribution a bit out of context:

"I usually have two music programs- one with the compression settings pretty close to that of the speech in quiet program, but the other is for streamed music. Streamed music was studied in depth by a Colorado group- if interested, I can sent you the relevant article link- but they argued that since streamed music (eg., mp3) are already compression limited once, doing it a second time with can be problematic, so that program is set as the first music program except in a linear (or near linear) format, depending on the needs of the client.

This all assumes though that the front end of the hearing aids have been taken care of and that the A/D converter doesn’t distort with high levels of input."

In reply to @tenkan

yes my provider has a “walk in. hour” that I used to retrieve my newly sent back aids. otherwise i’d have to wait some time for an appt. It was Saturday and the place was swamped and understaffed. I don’t fault my audi in this instance. Plus I had covid and was restricted. to outdoor wearing a mask.

In reply to @jeffrey

Yeah that’s a great insight, especially on the “streamed music (eg., mp3) are already compression limited once, doing it a second time with can be problematic” people need to be aware of this for sure.

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