The purpose of this article is to review the current state of evidence in areas identified by hearing aid used when asked about their expectations for their new hearing aids.
Hearing aid users are concerned with hearing in noise, comfortable loudness and physical fit and accessing sound through a variety of input types are expecting improved audibility. Hearing impaired individuals are counting on the audiologist to guide them through the selection process in order to create them cost effective solution suited to the type and degree of their hearing due tailored to their individual needs.
Dr. Catherine Palmer states that, “Audibility and binaural hearing continue to be key elements for better hearing noise,” when asked about current progress in hearing aids for the elderly.
Signal processing techniques used to remove unwanted sound include digital noise reduction, feedback suppression, and expansion digital noise reduction indeed reduce unwanted background noise. Feedback suppression can be employed without reducing sound quality and further there is acoustic evidence that feedback is reduced when feedback algorithms are employed.
Expansion signal processing allows less gain every soft sounds with the amount of gain increasing as the soft input level increases. This is the opposite of compression (decreasing gain for increasing input).
One of the most dramatic changes in the past five (5) years is the introduction of the open fit hearing aids. The feedback suppression has allowed fittings to leave the ear canal more open than ever before which provides physical comfort and improved sound quality related to the user’s own voice.
Improving audibility is the only specific goal of a hearing aid fitting and verification techniques surround the measurement of audibility with the newly amplified signal. Currently, there is no evidence to assist the audiologist in choosing between the three strategies employed in commercially available hearing aids.
In 2001, Stelmachovicz, et. al., provided clear evidence that individuals perform better with high frequency audibility. The potential positive outcomes that their writer described above are based on the expert fitting provided by the audiologist.
it is clear that the user’s individual expectations, communication needs and lifestyle must be considered within the fitting as well as appropriate verification techniques to ensure that the signal processing is functioning property.