Preferred Compression Amplification Setting for Individuals with Varying Audiogram Configurations

Abstract

Introduction: It is believed that increase in number of compression channels in hearing aids will help individuals having audiograms with different configurations. The cognitive abilities were also found to determine the benefit with multichannel hearing aid by interacting with the compression parameters like number of channels and types of compression. With this understanding, the current study aimed to evaluate the perceptual benefit and its relationship with working memory, with increase in number of compression channels in hearing aids in dual and syllabic compression setting. This was investigated in three groups of participants with flat, gently sloping, and steeply sloping SNHL. Methods: The aided speech perception benefit from increasing the number of compression channels in hearing aids was evaluated in 60 adults with bilateral mild to moderately-severe SNHL having flat, gently sloping, and steeply sloping SNHL (i.e., in three groups), using three hearing aids (having 4-channel, 8-channel, & 16-channel), in dual and syllabic compression settings, at two input levels (60 dBSPL & 80 dBSPL). Sentence identification score in quiet for phonemically balanced (PB-SIS) and high frequency (HF-SIS) sentences, speech quality rating in quiet, and SNR-50 (PB-SNR-50 & HF-SNR-50) were obtained in six aided conditions. To understand the relationship between working memory and aided speech perception, auditory digit-forward, auditory digit-backward, operation span, and reading span were also assessed in these three groups. Results: The aided sentence identification in quiet (PB-SIS and HF-SIS) indicated similar perceptual benefit with increase in number of channels, in syllabic or dual compression, at conversation and loud speech levels. The aided PB-SNR-50 did not significantly vary with increase in number of channels, in both compression settings, in the three groups. In gently sloping SNHL, a significant improvement in HF-SNR-50 was obtained with increase in number of channels in both compression types. The speech quality rating with syllabic compression improved with increase in number of compression channels in flat, and gently sloping, and in dual compression in steeply sloping SNHL groups. Aided speech quality rating revealed a preference for syllabic compression in flat, and gently sloping SNHL groups and for dual compression in steeply sloping SNHL group. There was no significant difference between groups present in all the aided speech perception measures investigated. There was a significant positive moderate correlation found between auditory forward-digit span with speech quality rating in flat and gently sloping SNHL groups. In contrast, the reading span negatively correlated with speech quality rating with decrease in number of compression channels in gently sloping SNHL group. In flat SNHL group, the PB-SNR-50 showed moderate positive correlation with auditory digit-forward span and reading span with increase in the number of channels. There was no relationship between working memory measures with aided SIS in three groups and with aided SNR-50 in gently and steeply sloping SNHL groups. Conclusion: Individuals with flat, gently sloping, and steeply sloping audiogram configurations benefit equally well with 4-, 8-, and 16- channel hearing aids in dual and syllabic compression setting, in terms of sentence identification in quiet and in noise. Quality perception improved with increase in number of channels in syllabic compression in the three groups and in dual compression in steeply sloping sensorineural hearing loss. Some of the working memory skills influenced the aided speech quality rating with multichannel compression amplification. Speech quality measures revealed the preference better for compression parameters in individuals with different audiogram configurations.