Extended Bandwidth, Limited Bandwidth, and Frequency Transposition
Lau et al (2014) compared three hearing aid fitting options across 13 adults (5 male, 8 female) with bilateral sensorineural hearing loss (SNHL). The three fitting options included a bandwidth limited to 4000 Hz (LBW), an extended bandwidth to 9000 Hz (EBW), and linear frequency transposition that transposed signals above 4000 Hz (LFT).
The purpose of the study was to compare participant’s performance using LBW, EBW, and LFT as the best fitting options for people with moderately severe SNHL has been unclear. The authors report previous literature has indicated EBW is preferred by people with normal hearing and “listeners with a mild degree of hearing loss also may prefer a broader bandwidth.” Each of the three fitting options were worn at home and in the lab. Minimal pair-word tests, data-logging, questionnaires, speech perception tests, subjective judgments and more were used to evaluate hearing aid fitting success.
Lau et al state that “the findings in the current study indicated than an EBW with an advanced amplification circuitry could improve the recognition of /s/ words relative to LBW. In addition, the EBW option was more preferable among listeners for home use than the other two amplification options. Logically, the current results support the use of the EBW option for individuals with a moderately severe, high-frequency hearing loss….” They conclude that “the findings in the current study support the notion of fitting an EBW as the better choice for this group of listeners….”
For More Information, References, and Recommendations
Beck DL, Olsen J. (2008) Extended Bandwidths in Hearing Aids. Hearing Review.
Lau CC, Kuk F, Keenan D, Schumacher J. (2014) Amplification for Listeners with a Moderately Severe High-Frequency Hearing Loss. Journal of the American Academy of Audiology. 25:562-575.