Hearing aids-external electronic devices used to help individuals with hearing loss-traditionally consist of a microphone, an analog-to-digital converter, a digital signal processor, a digital-to-analog converter, and a receiver that delivers an acoustic signal into the external auditory canal. In 2008, 97% of all hearing aids sold used digital processing. Catherine V. Palmer, PhD, provides a review of current digital hearing aids.
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December 2009Children are now being fitted with hearing aids by the age of 6 months due to successful early identification of hearing loss and new screening guidelines. Adult amplification recommendations are based on hearing evaluations and patients’ reported difficulties.
The choice of a hearing aid depends on a number of factors, including degree of hearing loss, site of lesion, ear shape and size, desired battery life, and patient preference. Behind-the-ear (BTE) hearing aids are attached to an earmold that couples the hearing aid to the ear canal. Other hearing aids can be in the ear (ITE) and in the canal (ITC) or completely in the canal (CIC). The newest style consists of a mini-BTE coupled to the ear with slim tubing ending in a small dome, leaving the ear canal open. The new styles can also make the distinction between having the receiver cased in the BTE or at the end of the sound channel (the slim tubing). Having the receiver in the canal allows for a smaller BTE case without loss of amplification; however, the receiver is more exposed to moisture, heat, and cerumen in the ear canal.