The Performance of Music and Speech with Different Frequency Lowering Devices

Abstract

Objective: Previous research studies have documented the benefits of both frequency transposition (FT) and non-linear frequency compression (NLFC) for patients with different degrees of hearing loss, however, very few studies directly compare the effect of two different frequency lowering (FL) techniques on the same population to investigate if superior performance in terms of speech and music perception exists. Design and Sample: The aim of the study was to determine whether people with a moderate to severe hearing loss have improved music perception and speech intelligibility with the use of FL and if the benefits is dependent on a specific FL strategy. A parallel research design was implemented and a purposive sampling method was used. Participants (n=20) were experienced hearing aid users with bilateral, moderate to severe hearing losses and no FL experience. A music perception questionnaire were completed by participants to rate their perception of music and the Music Perception Test (MPT) were used to assess participants’ musical performance. The Phoneme Perception Test (PPT) and Hearing-in-Noise Test (HINT) were used to assess participants’ speech perception abilities. Two commercial hearing aid devices with different FL approaches (FT and NLFC) were used. Results and Conclusion: Results indicate that participants distinguish high frequency sounds better with both FL strategies than without it resulting in better speech intelligibility in quiet and in noise. Greater speech scores with NLFC compared to FT was evident. Participants that used FT showed more confusion regarding speech perception. In terms of music perception the study shows that NLFC improves participants’ pitch and melody perception whereas mostly no musical improvement was observed with FT. With the use of FT participants’ ability to identify melodies decreased. A strong preference to listen to classical music with NLFC compared to FT was noted. Therefore it is evident that FL can improve speech and music perception for people with moderate to severe hearing losses but the perceived benefit seems to be dependent on the specific FL strategy implemented.