Music and speech have some differences which include spectral shape, intensity and “crest factors”. Most modern digital hearing aids cannot handle the more intense inputs that are characteristic of music.
Four new technologies and four clinical strategies will be provided to optimize hearing aids for music as well as for speech. These technologies are designed to circumvent some problems associated with the analog-to-digital conversion process- a major weak point with many modern hearing aids.
Audio files will be showing the problems of the hearing aid not being able to handle the higher level signals associated with music, as well as demonstrating the difficulties with frequency compression for music.
Given the limitations of most modern digital hearing aids to handle the more intense inputs that are characteristic of many forms of music, there are a number of clinical strategies and technologies that an audiologist may use to alter the electro-acoustic characteristics of hearing aids that otherwise work quite well for their clientele for speech. Clinical strategies consist of those approaches that can be remediated in a clinical setting while technological strategies are hard wired into the hearing aid circuitry.
None of these technologies or clinical strategies are software based. The technologies are built in to the hearing aid and cannot be adjusted clinically. Software adjustments are not the approach that should be taken whenever music is a considered input to a hearing aid. Data are shown for several hearing aid manufacturers’ technologies.
Clinical strategy #1: Reduce the input to the hearing aid, and if necessary, increase the volume.
Clinical strategy #2: Removal of the hearing aid for music.
Clinical strategy #3: Use a (tape) covering of the hearing aid microphone
Clinical strategy #4: Use an ALD with a volume control to reduce the input
Technology #1: Use a less sensitive microphone or one with reduced low frequency sensitivity
Technology #2: Analog compression prior to the A/D converter with digital expansion.
Technology #3: Changing where the dynamic range of the A/D converter operates.
Technology #4: Use of a post 16 bit IC architecture
Frequency transposition is problematic with music and this will be discussed at length along with audio demonstrations. There is one “island of refuge” for frequency transposition; namely one octave. This creates unexpected perfect fifths and major thirds in the music, but this is not dissonant, and as such this one octave shift may be acceptable to a certain proportion of music listeners and performers.
THREE LEARNING OBJECTS
After attending this seminar, the participant should be able to:
- Select software programming that is optimized for music
- Explain the engineering limitations of most modern hearing aids for music
- Identify some simple clinical strategies to improve a hearing aid for music