Something I want to document about my hearing. The hearing tests that the specialists do don’t capture everything that’s going on. The hearing tests measure how loud you can hear each frequency, but they don’t indicate the quality of the hearing.
I mean sometimes my wife sounds like a Dalek from Dr Who, music sounds terrible, out of tune, notes sound like the wrong note, a guitar sounds like a piano, and I can’t tell what some sounds are. (I have to ask “What’s that noise” – “Oh, you mean the fridge?”)
For the past 3 days any noise I hear between about 200 and 600 Hz all sounds the same. If I press notes on a keyboard app that is generating a sine wave every note sound the same.
If were to do an official hearing test, it would register me as having good hearing at 250Hz. But what the hearing tests don’t show is that my ear/brain is not differentiating and different in the tones of 250Hz and 500Hz.
It could be that the doctor’s don’t care about that, because the levels at each frequency give a good enough indication of the health of the hearing. Or it could be they are unaware.
Anyway I did 2 plots yesterday, one is of the sound volume level I am hearing, and one is of the sound quality.
The top graph has the usual shape of my hearing tests, worse at the left, better high, but the bottom graph is slightly different. I did this hearing level above manually, without an app, using a sine wave generator, so that I could track more frequencies. (32,40,51,64 etc instead of just 125Hz,250Hz etc). The official tests have big gaps between the frequencies being measured.
The second graph shows the ‘Quality’ of hearing. I gave each frequency a quality score from 1-4.
My worst ‘quality’ of hearing is from 200 to 800Hz.
My worst actual hearing is below 200Hz, but it sounds clear.
I actually prefer the loss of hearing to the bad hearing.
For the frequencies around 400Hz, then I turn them up they sound all wrong. Out of tune. Like a Dalek. Underwater. The hearing tests do not measure this. But I can hear it in my head.
I can also measure it by doing a frequency sweep from say 100Hz to 1000Hz. This is where you play a single note and slowly increase the frequency of it. I can hear a single tone increasing in frequency up until about 200Hz, then the tone disappears and I hear one massive noisy tone overwhelming everything else, my guess is it’s around 400Hz but it’s hard to tell. Then, when the rising pure tone hits around 700Hz, the strange tone disappears and I can hear the individual tone slowly rising again and by 800Hz it’s clear again. At 300Hz-600Hz the background noise is so bad I lose the single tone altogether.
The third way I can hear this loss of quality is if I play a scale on a piano app that is playing a sine wave. The notes from C4 (262Hz) up to C5 (523Hz) are almost indistinguishable – they all sound like the same note. To help improve this I am playing myself songs in this scale, and trying to imagine what they should sound like.
I am playing ‘I am not done changing’ which covers C,D,E,F
I am playing ‘Amazing Grace’ which is so familiar to me from a young age so I can ‘hear’ (imagine) the notes even when my ear is not hearing them and try to force/train my ear to heat them properly. Amazing Grace also has a good message so that encourages me!
Twinkle Twinkle little star has a simple melody and is also well known from a young age so it’s a strong memory.
Joy to the World just goes form C down to C, hitting every note – so it’s very useful!
Today I was able to isolate the ringing to exactly 320 Hz and an octave up at 640 Hz. By playing it back into my ear while I was writing this article it seems to have mostly gone!
CIST and SSHL 