Preferred Low- and High-Frequency Compression Ratios among Hearing Aid Users with Moderately Severe to Profound Hearing Loss

Abstract

This study aimed to determine the low- and high-frequency compression ratios of a fast-acting device that were preferred by people with moderately severe to profound hearing loss. Three compression ratios (1:1, 1.8:1, and 3:1) were combined in the low and high frequencies to produce nine schemes that were evaluated pair-wise for three weeks in the field using an adaptive procedure. The evaluation was performed by 21 experienced hearing aid users with a moderately severe to profound hearing loss. Diaries and an exit interview were used to monitor preferences. Generally, the subjects preferred lower compression ratios than are typically prescribed, especially in the low frequencies. Specifically, 11 subjects preferred linear amplification in the low frequencies, and 14 subjects preferred more compression in the high than in the low frequencies. Preferences could not be predicted from audiometric data, onset of loss, or past experience with amplification. The data suggest that clients with moderately severe to profound hearing loss should be fitted with low-frequency compression ratios in the range 1:1 to 2:1 and that fine-tuning is essential.

Transitioning Hearing Aid Users with Severe and Profound Loss to a New Gain/Frequency Response: Benefit, Perception, and Acceptance

“…Until relatively recently, the evidence to support the use of advanced signal processing technology for this population has been sparse, which may contribute to the reluctance of audiologists to fit their severely and profoundly hearing-impaired clients with the features described above. Audiologists also may face opposition from the clients themselves, as hearing-aid users with severe and profound hearing loss may, due to their dependence on amplification, perceive that the risks of altering their amplification characteristics outweigh the potential benefits (Keidser et al, 2007;Keidser et al, 2008). When participants in the Keidser et al (2007) study were initially introduced to nonlinear amplification, using a gain-frequency response shape that often provided less gain across the low and midfrequencies than they were used to, many commented that the devices seemed insufficiently loud relative to their own linear or near-linear hearing aids.…”

“…Audiologists also may face opposition from the clients themselves, as hearing-aid users with severe and profound hearing loss may, due to their dependence on amplification, perceive that the risks of altering their amplification characteristics outweigh the potential benefits (Keidser et al, 2007;Keidser et al, 2008). When participants in the Keidser et al (2007) study were initially introduced to nonlinear amplification, using a gain-frequency response shape that often provided less gain across the low and midfrequencies than they were used to, many commented that the devices seemed insufficiently loud relative to their own linear or near-linear hearing aids. Consequently, these participants were concerned that the new lower gain levels for medium-and high-input levels would prevent them from adequately hearing, and therefore functioning, in their daily life.…”

“…As a consequence, hearing aid users with severe and profound hearing loss often were provided with, and have therefore adapted to, compensatory gain in the low and midfrequencies. This was evidenced by a comparison of the gain/frequency responses, as measured for a 65 dB SPL input level, of the participants' own devices in the Keidser et al (2007) study and the National Acoustic Laboratories' revised formula with profound correction factor (NAL-RP [Byrne et al, 1991]). A frequency response that provides gain in the low and midfrequencies that is significantly higher relative to gain in the high frequencies is likely to have detrimental effects on speech understanding due to upward spread of masking, particularly in environments with high levels of low frequency-weighted background noise (Dillon, 2001).…”

Candidacy and Device Options: Personal Amplification Systems for School-Aged Children

“…Several recent research studies have demonstrated the merits of WDRC for children, especially when combined with digital signal processing. [30][31][32] In many contemporary hearing aids, WDRC and compression limiting are dually employed to allow for appropriate gain across a wide range of input levels and reduce high-level distortion, respectively. Furthermore, a low compression threshold (e.g., 45-dB SPL or lower) may be particularly beneficial for children, as it allows for appropriate gain to enhance audibility for low-level phonemes such as /s/, /f/, and /th/.…”

Optimisation of Service Provision for Adults with Severe and Profound Hearing Loss

“…Hearing aid fitting should be done carefully with appropriate counselling about what differences to expect from the sound. Low compressions ratios and long time constants are recommended to give comfortable gain without distortion and preserve valuable cues (Keidser, 2007;Souza, 2009). Hearing aid performance should be adjusted where cochlear dead regions are present (Baer et al, 2002, Vinay & Moore, 2007.…”