I'm often asked why digital hearing aids are so expensive when there are advertisements on television and in magazines for "personal sound amplifying devices" that promise that you will "hear better than ever before!" for only $29.99 [and if you act now, get a second device free!]. While always taking the time to explain in great detail as to why "you get what you pay for", I've never seen it explained quite as well as Dr. Judith Albrecht did in the recent member newsletter from the Pennsylvania Academy of Audiology.
Dr. Albrecht, operating under the assumption that pictures do more than words, reprinted a graph illustrating how these devices under-amplify the high frequencies, the range of sounds that are essential for speech understanding, while over-amplifying low-frequency sounds. The over-amplification of low frequency sounds has a negative effect on benefit, making the world sound too noisy and masking valuable speech content in the higher pitches.
In her graphic, re-re-printed below [click to enlarge], the o--o--o line represents a patient's thresholds which are very representative of the average sensorineural hearing loss that most patients suffer from. Anything below that line is inaudible to this patient, while anything above it is audible. At the other end of the loudness spectrum, the U--U--U line represents the loudest sound the patient can tolerate and so anything near that line or over it will be perceived as uncomfortably loud.
As you can see, the custom digital hearing aid does a much better job of making the high-pitch sounds --again, so necessary for improved speech intelligibility-- audible while preventing sounds from getting too close to the patient's tolerance levels.
If the hearing loss that almost every patient has, the sensorineural hearing loss, were easily rectified by just making sounds louder, then the the cheap little $29.99 amplifier would be the perfect solution. Unfortunately that's not the case, but fortunately, there are plenty of audiologists nearby waiting to be of service to you.
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