Friday, April 24, 2009

Do high frequencies really matter much at all?

I used to be more obsessed(I have OCD) about wanting to hear high frequencies but after researching it on the internet, I begin to wonder exactly how important the highs are? Someone in this forum said 75% of environmental sounds are low frequencies so 20% must be mids and 5% highs. Thus I am missing very little in the way of environmental sounds and ive been told by friends and family that they too would not miss the annoying high pitch sounds as long as their speech comphrension remained normal. Hear Again no longer hears above 2000Hz(too annoying) and doesn't miss it since her speech comphrension remained unchanged. She even said music sounds better without those annoying high tones!

As for speech, several posters here keep saying how important 2000-4000Hz is but Hear Again had 6 high frequency electrodes disabled and doesn't really hear above 2000Hz anymore, yet her speech comphrension has not dropped at all! My own dad has a moderate high frequency loss, yet he has absolutely no trouble understanding speech and can even hear S, F, TH sounds! I even checked the speech banana and most of the letters fall in the low(er) frequencies. The highs help with S, F and TH but even those speech sounds aren't puretones and have lower frequency components. I can hear S and F, just not tell the difference between the two.

From reading on the internet and that article I posted I have logically concluded that low frequencies(125-500Hz) account for 60% of speech, the mids(500-2000Hz) accounts for another 30% and the highs(2000-8000Hz) account for the last 10%. My dad and Hear Again is missing that 10% but still understands 90% of speech. My dad understands close to 100% since he hears unaided naturally.
I am also missing that 10% and alot of the 30% but I am able to access all of the 60% and some of the 30% which is why im currently understanding about 70%(up to 80%) of what my dad says without lipreading.

My results are probably a little above average. Look at this post where this profoundly deaf man scores over 90% speech! So if people like him, me and many others can still score great on speech comphrension using our residual low frequency hearing, it sounds like(pun intended) high frequencies simply add clarity and details to speech and sounds(which is never a bad thing) but low frequencies are the fundamental structure of speech as well as environmental sounds.

I gotta be honest there that I have no real idea what high frequencies are like, how can I miss what I don't know? It's like my colorblind brother, to him, his world looks normal(in it's browns, blues, yellows) and he argues that colors aren't that important. I guess it's nice to see all 1 million colors instead of only 10 thousand. But I agree that my brother's colorblindness hardly affects his life other than posing some inconvinences when many different colors appear identical and he confuses them. He has trained himself to differnate colors by hue, for example red and green look like different hues of brown with red being a much darker hue.

I have learned something akin to what my brother learned with sounds. I can fill in the missing gaps when listening to speech. S and F sound like "ehhh" to me and when listening to sentences, I can usually deduce the proper letter unless the word happens to be a rhyming word such as "fit" and "sit" but put in a sentence, I usually know what the word should be. My own audiologist says I should keep training my brain to discern different words then it will begin to come naturally to me instantly and readily. I notice my brother discerning colors instantly because he has trained his brain to differnate the hues.

To summarize it up, high frequencies 2000Hz and above account for only 5% of environmental sounds(shrill whistles, squeals and squeaks) and only 10% of speech(S, F, TH consonants) so I ask again exactly how significent is missing on a small percentage of speech and sounds? How much of a difference does it make to those who are hearing or still have high frequency hearing? Has anyone tried a comparsion? I will be trying that at my audiologist by telling him to turn off the gains above 500Hz then to turn off the gains below 500Hz.

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