Can you tell the difference in streaming bit rates on your CI?

[Tim]

There was a discussion about CIs and music on Discord.  Some CI wearers said that they were surprised that they could hear a clear quality difference between Spotify and Tidal streaming services.  (I think @John Schulz was one of the people!)

Presumably this is due to the bit rate or compression.  I (we?) figured all the digital processing and "loss" along the way for a CI would overwhelm any quality difference of bitrate but some people said they could hear the difference.

In a later discussion today, an audiology expert from USC shared this NPR link that plays parts of six songs at three very different "quality" levels and asks the user to pick which one is the best. 

https://www.npr.org/sections/therecord/2015/06/02/411473508/how-well-can-you-hear-audio-quality

I'm curious whether anyone here can hear a difference on their CIs.  I could not tell any difference, effectively 0/6. 

I also tried with my good ear and still struggled.  Maybe I need to pull out better headphones and really concentrate. 

I may try in other ways to see if I can tell a difference on my CI but this was hardwired to decent headphones so it should have also eliminated any Bluetooth compression artifacts. 

This is prompted in part by Spotify raising prices. I've been using it heavily for rehab to listen to music on my CI.  Tidal is a streaming service that emphasizes quality with higher quality (high bitrate, lossless compression options.)  I'm not eager to change platforms but thought that I would check things out.

 

 

[John Schulz]

@TimDo you have a fully "naked" program; no compression, noise reduction. wind suppression, etc.?

[Tim]

@John Schulz Okay, good suggestion.  I was using my "everyday" program of AI Mild. 

My naked program is Omni mic, AI off, ANR off, WNR off, TNR off.  Still leaves default Med-El compression of 3:1 though. (Do you have a different ratio set?  If so to what and why?)

I re-ran all 6 samples again but this time with my "naked" program, S2 under headphones rebalanced to be 100% to the CI so my good ear can't do much cheating.

Again, I still can't tell any difference on any of the six songs. Note that it looks like they rearrange the order of the songs each time you refresh the web page.   Again 0/6. 

Can you tell a difference?  Of course you are more than a decade ahead of me in terms of rehab!  🙂   

Next up I'm going to try streaming but can't imagine that will be any better.

[Tim]

@John Schulz Used Audiostream to my S2 with my naked program.  I thought I meant have had a feeling of a slight difference on two songs.  Picked wrong on one, right on the other.  Couldn't make any difference on the other 4.  Seems like blind luck for me, I would give my self another 0/6.

Unrelated but interesting that the quality was so much better and more pleasant under headphones.  Presumably that is because of my good ear cheating to help out in any of multiple ways even when I had that side turned off completely.

 

[John Schulz]

The AudioStream is definitely the bottleneck haha and won't sound anywhere as good as AUX/high bit rate digital. I took the test and got four out of six right with the two wrong ones being 320k. The difference between 120k and 320 is very dramatic for me on all of them. The difference between 320k and lossless was much less noticeable but definitely there for most of them. The two main things that I notice is that with high/uncompressed, I can hear everything in fuller detail versus things being blocky in the background and around transitions and with smooth tones, there's less ripple in the note.

As for the compression, all I was told is that it's just "off" so I assume that means a 1:1 ratio?

[John Schulz]

As for why... I was running into an issue where I would get horrific crunching if I listened to a song with a lot of bass mixed with other tones. If you want to know what I'm talking about, the start of Look At Me! by XXXTENCACION (explicit song so discretion advised) replicates the effect I experienced nearly identically.

[Tim]

Even listening on decent speakers and with my good ear fully helping, I could not find anything important.  I was able to find subtle differences on a few but just couldn't make out anything on the others.

Congrats on being able to distinguish between them @John Schulz, I'm happy saving money, bandwidth, and storage space not needing to worry about higher bitrate/lossless versions.  🙂

Seems like we are both winners!

 

[pdk]

On 4/12/2024 at 9:42 PM, Tim said:

Even listening on decent speakers and with my good ear fully helping, I could not find anything important.  I was able to find subtle differences on a few but just couldn't make out anything on the others.

Congrats on being able to distinguish between them @John Schulz, I'm happy saving money, bandwidth, and storage space not needing to worry about higher bitrate/lossless versions.  🙂

Seems like we are both winners!

 

Great thread. Managed to get 2 right but on 2 I chose the mp3. 

But different music genre also appears to have different quality.. 

As for specs on electrode frequency I would say it's totally meaningless. My low frequency spec is 180hz

I can hear the bottom note on a piano clearly now. So how does that work? 

There also seems to be a different experience for each of us,  there is no telling which instruments sound best. 

Luckily for me there is a large amount I can enjoy. My advice is try anything you will be surprised. 

Head phones beat Bluetooth any day. 

[Tim]

@pdk  Great to hear from you and thanks for chiming in with your experience. 

It is encouraging that you and @John Schulz both have enough music hearing quality to distinguish differences.  One thing you both have on me is time.  I'm only 15 months into my journey and I expect music to take longer than voice.  I look forward to possibly getting to the point you two are at where you can distinguish some differences.

[John Schulz]

On 4/15/2024 at 9:52 AM, pdk said:

Great thread. Managed to get 2 right but on 2 I chose the mp3. 

But different music genre also appears to have different quality.. 

As for specs on electrode frequency I would say it's totally meaningless. My low frequency spec is 180hz

I can hear the bottom note on a piano clearly now. So how does that work? 

There also seems to be a different experience for each of us,  there is no telling which instruments sound best. 

Luckily for me there is a large amount I can enjoy. My advice is try anything you will be surprised. 

Head phones beat Bluetooth any day. 

You are right in the genre having an effect on noticeable sound quality. The more instruments and vocals there are at once, the more noticeable the compression is. The One Republic song was instantly noticeable for me while I really had to focus on the orchestra one to notice the compression. I am curious what the max polling rate of the mics are on the CIs because I would guess it's less than 120ksps. Maybe @MED-EL Moderator can answer this.

Since I've started experimenting with compression, I've had a new understanding of how it works. The way that I like to think of it is as a percent loss at each stage. As a a hypothetical example, if you stream Tidal over Bluetooth through uncompressed CIs, the loss might look like .95 (Tidal), 0.80 (AAC), then 0.80 (pollimg rate of the mics). Thus the resulting quality in this case is 60.8%. In @Tim's case, the highest point of loss might be the brain's ability to interpret the sound or the compression setting he has. If it's something like 0.4, any changes in the other factors will be negligible in the final result.

[Tim]

 

The word compression means two very different things in this setting.  The dominant interpretation of usage of compression is about approximating a big file in a smaller size either through some loss of quality with the benefit of some file size reduction (lossy compression) or compressing in a way that doesn't affect quality at all (lossless compression).  This is what we were talking about when it comes Spotify and Tidal music compression.  (I'm sure John and PDK are very familiar with this!)

Perhaps others familiar with the following but I keep forgetting so I decided to write up some quick notes for future reference.

Hearing aids and CI's use the term compression in a very different way.  Here is a Med-El page that talks about it.

Really Med-El's compression term describes squeezing the broad bandwidth of normal hearing into a smaller range that the "electrical hearing" can transmit/sense.  Effectively it is "range compression".  This may or may not result in any "data compression."  With the move to digital hearing aids, it would have been nice if they had found a different term for compression, say "compaction". 

The web page above also doesn't really explain the term compression ratio that seems to have a common default of 3:1.

Perhaps the 3:1 ratio is about how much to compress from the MAPLAW part of the diagram to the electrode part of the diagram.  (Appears to be a range of 60 dB to a range of 20 dB or 3:1.)  Does anyone here use a different compression ratio than 3:1, if so why?  Perhaps our audiophiles use a different range for a music program or our old timers like John have a different default set. 

Here is a screen capture from my Rondo program showing the compression ratio along with the more commonly modified items.

 

[Anthony Canada]

@Tim here is an article that goes into detail about the AGC ratio. It isn't written with your exact observations in mind but it does touch on the subject including 3:1 and 12:1 ratios. Further simulations of the effect of cochlear-implant pre-processing and head movement on interaural level differences - PMC (nih.gov)

I think I have an article at home about the basal membrane's natural ability to do something similar which is somewhat mentioned if you click through from the link Tim provided to Cochlear Implant System | MED-EL Pro (medel.pro) about a third of the way down is a section on loudness growth and you can click/unclick on the graph to see the BM's loudness growth vs MedEl.  

[Tim]

@Anthony Canada Thanks for the article links.  The first article brings back distant memories of an undergraduate digital signal processing class. 

Interesting to see how varied the approaches are for each of the three companies and yet seemingly most patients for all three achieve good outcomes.  The experimentation also highlights that the research is still ongoing and that the processing may continue to improve over time to give us all even better outcomes in the future. 

[Mary Beth]

For those who can tell a difference between the samples, it is interesting to take the test under different conditions and compare…

computer speakers

headphones

AudioLink

AudioStream

Artone BT neckloop

Roger System

to see the way each option impacts audio.

[pdk]

At the moment I have an n7 on one ear and n8 on the other which is definitely impacting on my hearing . I can hear differences in the test streams but not tell the one that has best quality. If you only listen with one ear you are only listening to one channel. Bi-lateral provides so much more which maybe allows me to hear closer to the real sound. I think listening with head phones is best because you are closer to the source of the sound. The sound from my TV streamer is badly degraded. 

Comparing sounds is also difficult you have to keep flipping to and fro. 

For me it all cones down to finding the music that sounds best. 

The quality is not the most important. 

Most of you will have never listened to music on shortwave or mediumwave radio it was great unti FM came along and those days I had really good hearing.