Believe it or not, whether your hearing loss was made worse by jet engines, diesel tractors, hunting rifles or Skillsaws, the outcomes are not dissimilar. And, of those suffering with sensorineural loss in the United States today, those with normal lows and a precipitous drop in highs make up the majority. Not to minimize the difficulty of your type of loss, but to let you know that you're far from being alone.
For that reason, the hearing industry has spent considerable research and resources into your type of hearing loss. That doesn't mean that amplification is not a viable solution; it means that there will never be amplification strong enough to raise dead hair cells to life, nor should it even be attempted considering abnormal loudness growth and cochlear distortion issues.
Instead, we need to think in terms of "improvements" in auditory function, keeping in mind that high frequency regions of human hearing are the most crucial for speech understanding and for function in noisy listening environments.
Recent advances in "open fittings" are of particular value to those with normal lows and mids--who otherwise would be put off by "occlusion" or a plugged sensation--and moderate to severe drops in the highs. For steeper drops in the highs are several new applications, again limited by how much high frequency gain can be applied without inciting loudness growth problems, and without unmanageable acoustic feedback. In all cases, behind-the-ear type instruments provide the greatest advantage because of microphone and receiver proximity and more powerful amplifiers.
But, we must keep in mind that just because a wide swath of high frequency thresholds cannot be corrected to a normal range does not mean that the octave or two that can be improved is not of significant value. That bit of help can go far in improving signal-to-noise and restoring a degree of the more important central auditory abilities.
I'll need to leave it to your hearing care professional to explore the new options for high frequency losses. However, I would like to share a few postulates relative to successful high frequency hearing aid fittings from our research at DigiCare Hearing Research & Rehabilitation that may be helpful, if observed. I will also include references that can go far in helping you and your hearing health professional solve some of the mysteries of your type of loss:
- Whatever type of coupling is utilized it's fitting must take into consideration the sensitive neuroreflexes of the external ear canal, so as not to introduce unpleasant artifacts into the equation, such as non-acoustic occlusion, lymphatic swelling of tissue, or over-stimulated tympanic plexus at the eardrum. Equally important, the acoustic coupler to your ear should not cause the removal of keratin over the epithelium of the ear canal (Chartrand, 2005b).
- Your amplifier should be an advanced DSP (digital) processor with the widest acoustic bandwidth possible to provide more spatial information to the central auditory process, and to improve signal-to-noise ratio. The wider the acoustic landscape, the better to understand in noise, regardless of limitations in your hearing's actual bandwidth.
- You will need some way to be able to adjust the volume throughout the day, for no one's hearing sensitivity is constant from hour to hour or day to day. For that reason, unless contraindicated by dexterity or cognitive limitations, we always recommend a user volume control in cases of high frequency losses (Chartrand, 2003).
- After all is said and done with amplification, please remember that ear-level amplification is not the end of the road. There is also a whole new world of assistive technology with which to pick up where hearing aids leave off (Diles and Diles, 2005). Your hearing health professional should be well-versed in the many applications and technologies available today.
- Finally, in response to your mention of accompanying tinnitus, you might be interested in reading one our recent studies on tinnitus management in losses like yours. For the severity of the tinnitus in such cases has been found to correlate closely with sensory deprivation (non-use) of the high frequencies--another reason for amplification even when outcomes are limited (Chartrand, 2005a).
Max Stanley Chartrand, Managing Director
DigiCare Hearing Research & Rehabilitation
Chartrand, M.S., (2005b, May). Identifying "Neuro-Reflexes" of the External Ear Canal. AudiologyOnline, Archives, http://www.audiologyonline.com/articles/identifying-neuro-reflexes-external-ear-1030.
Chartrand, M.S., (2005a, April). Tinnitus Loudness Perception in Precipitous HF Losses. AudiologyOnline, Archives, http://www.audiologyonline.com/articles/tinnitus-loudness-perception-in-precipitous-1035.
Chartrand, M.S., (2003, March). Use Volume Controls: Fit(tings) to be tied! AudiologyOnline, Archives, http://www.audiologyonline.com/articles/user-volume-controls-fit-tings-1135.
Diles, C.G., and Diles, W.S., (2005, August). Staying in the Loop: When Hearing Aids Are Not Enough. AudiologyOnline, http://www.audiologyonline.com/articles/staying-in-loop-when-hearing-1017.