There is something that I am not seeing addressed in any of the posts so far. I am an engineer and have done some testing on my own. I noticed that all audiograms test for threshold where we can no longer hear a tone. However, I am finding that at normal listening volumes my hearing profile is much different than the threshold (audiogram) shows. My hearing does not drop off nearly as badly as the audiogram shows and the difference between my ears is much smaller. Instead of 20 db drop offs at higher frequencies, it is more like a 3 or 4 db. So for audiophiles who are listening to music at normal volumes it would be important to have a hearing test for frequency response to see what adjustments are actually needed and not only for hearing threshold that is of little importance to music listening.
How did you test this?
Have you explored whether your thresholds are different if the audiologist uses a more distinctive tone?
Loudness growth measures and MCL tests have been around for years - they can measure how you perceive sound growth with your particular level of recruitment. Somebody even used to make a ‘smiley face tool’ to allow the client to respond with how they felt about different loudness presentations.
However, they’re massively subjective, don’t deal with competing sounds in real environments (Lombard Effect) and don’t categorise the levels relative to all the sound energy across the sound spectrum. Meaning that the results will vary by the context, mood and sound stimulus used.
Like you noted, your preference for music probably means you’d express way more loudness growth ‘in music’ but if i played you speech babble with a noise sample over it, you’d hit the decline button much faster. Which loudness result is appropriate for you, at home, in your car, in a bar with friends and music?
I have provided a brief description of how I did my own testing in a response to Neville – just a short time ago. I can provide a more detailed description to those who are interested. Just let me know.
I had two audiograms done and the results were somewhat comparable. The first was at Cosco and it showed some hard-to-believe variations from frequency to frequency although the overall results were roughly similar. The second one was at a business that specializes in hearing aids and made more sense. They used the three repeating beeps that were easier to hear. I am not questioning the validity of the threshold test results. What did not make sense to me was how to correlate those to my real-world experience at more normal volumes. At normal and low listening sound levels I am getting quite a different result in how my ears respond – basically flat out to 5 kHz and then only a 10 dB drop at 8 kHz. And yes I can hear 10 kHz if I turn up the volume even more. That is way different than the 30 dB drop off from the threshold test. As I mentioned in my response to Neville, that may be something that could be important to those of us trying to get the most realistic sound when listening to music.
If I am interpreting your message correctly, it seems that you are in favor of providing a self-adjusting capability to those reasonably knowledgeable in sound technology – kind of like a violin player tuning their own instrument.
Loudness growth testing ‘could’ be something that a manufacturer includes in their app. Especially for fine tuning custom programs; that’s possible and within the realms of app development if there’s sufficient demand.
I am curious about the testing you did in more detail. I found you posted something general but more details would be helpful if anyone wants to try to replicate it. Possibly it would be better to post more details in the thread about this?
Have you been able to use this information to improve your hearing or aid adjustments for day to day living?
Here are some details of my test setup. I used a BK Precision 4017 signal generator that produces a constant output at all frequencies. It was set for a 100 mV peak-to-peak output. This waveform was sent to a 10 Kohm 10 turn potentiometer as a voltage divider to provide an accurate adjustable voltage signal to the earphones. The amplitude of the signal at the earphone connection was then measured on a Tektronix 7904 oscilloscope with a plug in that has 5 mV/div sensitivity. I should mention that any signal generator or scope that has this capability will work just fine. The attenuated signal from the potentiometer was then fed to my Sony MDR-V6 over-the-ear headphones. I did also measure the sound level at the earphones with a dBA sound level meter and for most of my testing used low volume tones of about 35 dBA. I did also do frequency scans at higher volumes to see if the results were any different. They were not. However, the results are very different with a much better (smoother) frequency response than my audiogram that only measures hearing threshold. Let me know if I have missed something.
How do you account for the acoustic coupling from the headphone to your ear-drum?
Audiometers are calibrated to ensure the correct SPL at the drum, do you have a 2cc 0.707 or Zwislocki coupler on a calibrated Bruel and Kjaer reference mic to a calibrated sound acquisition system?
These are over-the-ear headphones so there should be minimal coupling. As another test to confirm my results, I set up my 10 channel Equalizer to compensate for the perceived loss I was measuring at normal listening levels. In listening to orchestral music, I was impressed how well the compensation worked. It gave me exactly the audio result that I was hoping for. I did this test with both headphones and my high-quality speakers and there was no difference. From that I infer that my earphones are not affecting the sound I am hearing by any coupling effects. I did not stick anything in my ears as they do for the audiogram threshold test. I am not questioning the results of the audiogram threshold test – just that it may not be the optimal answer at normal listening levels.
Which all great, but completely ignores the transfer function of the approximately 7cc of the air that sits under the can which, will generate frequency specific reactance values at differing SPL. This is why you need a datum and calibrated transducers.
Excellent you’ve set up the ideal levels for your ‘ideal’ music listening on your graphic equaliser. Please don’t assume that this preference equally applies to how your hearing aid should be set-up.
“…approximately 7cc” I had no idea that my ear canal has such a large volume? Did you by any chance mean 0.7 cc? Sounds like the precise positioning of the hearing aid earpiece is very important to how well it will work.
No, the encapsulated volume under a headphone can is deemed to be approximately 5cc though larger Western male ears can be bigger. This includes the volume of the concha as well as the canal.
You’d normally have about 0.7cc residual volume behind an IIC aid.
What an interesting observation, Electroniker. For starters, I think all tone threshold audiograms should be conducted with the beep-beep option rather than steady - because that can submerge into tinnitus. And, yes, like you, I have noticed although not yet measured, the non-linear behaviour within real music: it’s almost as though a ‘gate’ is active within certain frequency bands, but not equally across each of them. Turning up the volume generally obscures it, but it would indeed not be revealed by standard tone tests.
Then there’s the matter of ‘recruitment’ - i.e. how much spl we can tolerate.
Perhaps that one could better be assessed by using a steady-level multi-tone track, say 15 to 20 simultaneous frequencies, more representative of music?
But, hey ho - everyone’s hearing is different!
What got me started down this exploratory journey is that audiograms from two different providers gave the same result that showed that my right ear was 10 dB worse than my left ear. On the log scale that means it’s 10 time worse or that I hear only 10 % of what my left ear hears. That made no sense to me since in listening to tones or just normal sounds my right ear is at most just a few dB weaker – no more than 10% or one or two dB. The only explanation that I could come up with it that my right eardrum has some scar tissue from a childhood infection. So maybe it won’t respond as well to the threshold test but does OK at normal volumes. My other observation was that my hearing does not drop off nearly as much as the audiograms indicate at frequencies above 500 hertz. So having someone set up hearing aids using the threshold test would give an unbearably bad correction. I sure agree with you that everyone’s hearing is different, but it seems to me that relying only on the threshold test may not produce the desired results and is likely to result in multiple visits to make adjustments that are more accurate at normal sound levels. It seems to me that there should be something more accurate than just the threshold test. Since I am an electrical engineer, I was able to set that up in my lab and produce my own frequency response results at various sound levels.
10dB doesn’t mean 10x worse though.
In terms of measured hearing perception it’s about half as loud though, not 10x. However, due to the way your brain gain-averages and adjusts to your personal recruitment, you won’t perceive it like that in terms of loudness/reduction in sensitivity.
There’s a real difference between understanding the mechanics of power scaling at an engineering level and how it works at a gooey level whe the tyres hit the tarmac.
Indeed there must be an opportunity for a manufacturer to devote the kind of musical insight and care that goes into the best mikes and loudspeakers - along with detailed performance specifications and (of course) an option to self-adjust if we feel that brave.
Probably, because of a smaller market, they’d arrive with a ‘boutique’ price tag. …And while on that topic, I have to say that the most musical BTE aid I have heard in 30 years is a ‘Cyber Sonic’.
Sweet, warm, no artefacts, not deafeningly loud, though not enough high end for my ski-slope ears. Possibly it is analogue. Price on eBay: five English pounds, delivered! There are several such to choose from, most quite clunky to look at, but for enjoying music at home who cares?
I think one of the deafness charities should gather up some such examples of truly affordable instruments and publish listening results. It’s unfortunate that hearing aids are a ‘distress purchase’ - which opens the door to inflated prices.
Oh, that ‘dismal whirl’. Well said, classicalmusic. Decades went past until I happened upon an audiologist, bless her kindly young soul, who went the extra mile to make the best of some very basic UK national health BTEs. Gave me the lows, down to 40 if you please, and sharply low-passed the highs to match my hearing cutoff and minimise a pointless challenge to processing. She set volume compression across the range, rather than band-by-band.
Speech is less helped, of course, but my current priority is enjoying (on hi fi speakers) a wonderful gift of 150 classical CDs from a neighbour!
Prior to my Phonak M70s I was tried with a pair of Signias. Oh, the overshoots (that’s mis-design) and general clog-and-crud whenever all the violins played, or the whole choir sang. And, the receivers had a sharp mechanical resonance at different points in the octave, which caused soloists to jump left and right, phrase by phrase.
Just to be fair, maybe more recent Signias, or the more costly ones, are better.
Our wonderful hearing aids are “medical equipment”
I wish that was a reason to sell hearing aids that allow us to play and enjy music, rather that “Just Good Enough” to understand words…
I understand your point and I think overall we are in pretty good agreement. However, at normal and soft sound levels my ears are almost the same with at most a few percent less sensitivity in my right ear. It is not even close to perceiving tones as “half as loud”. And frequency response is also significantly better than the audiogram would indicate. So maybe we have to work with the “gooey level” as you suggest.