Utility of Nonlinear Frequency Compression in Children with Severe to Profound Hearing Loss

Abstract

A major difficulty faced by children with severe to profound hearing loss is the limited benefit from conventional amplification, particularly, at high frequencies. This puts them at a disadvantage of not perceiving high frequency information which is essential for speech and language development. The present study aimed to investigate the utility of nonlinear frequency compression (NLFC) in children with severe to profound hearing loss who have limited or no benefit from high frequency amplification. Two groups who differed in their 4 kHz aided threshold were considered. Group 1 had 12 participants whose aided threshold at 4 kHz with their own hearing aid was 60 to 80 dBHL. Group 2 had ten participants whose aided threshold at 4 kHz with their own hearing aid was >80 dBHL. Detection thresholds for tones and for Ling’s six sounds, identification of Ling’s six sounds, and speech identification scores in quiet and in noise were obtained with and without NLFC. Results indicated a benefit from NLFC for aided detection thresholds at 500 Hz, 2 kHz and 4 kHz for Group1, whereas Group 2 improved significantly only for 2 kHz. NLFC proved beneficial for improving aided awareness thresholds and identification of high frequency speech sounds for both groups, with Group 1 obtaining more benefit compared to Group 2. It can be concluded that NLFC can be beneficial for children with severe to profound loss and that it can be a viable amplification option in this population as in children with sloping hearing loss.