High power hearing aid and choclear damages

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I'm doing a study on young people from 15 to 18 year old  using high 
power hearing aids ( 130 to 140 db of MPO). All of them 've  got   ,in 
the last ten years,   an increase of hearing loss of around 20 dB in the 
area between 1000 to 2500 Hz . 
I'm looking for people who have experience in  choclear damages in hear 
impaired people
If somoeone is interested to collborate please conctact me.