Sound quality assessment in cochlear implant and hearing aid users - SQ_CI

The study consisted of several phases. In the first phase, the aim was to be able to change the parameters of the hearing aid fitting in a controlled and standardised manner. To this end, a master hearing aid (Grimm et al. 2006) was used instead of a real hearing aid, with which the basic function of level- and frequency-dependent amplification in hearing aids can be simulated. The target parameters included low-frequency (<1 kHz) amplification and compression. The aim was to test the extent to which changing these parameters leads to an improvement in sound quality in bimodal cochlear implant fitting compared to a common prescriptive fitting rule (DSL i/o, v. 5, Scollie et al., 2005). The sound quality was assessed using the MUSHRA method, whereby three different music signals were presented. It was initially shown that most of the test subjects were able to give a reliable assessment of the sound quality. After adjusting for non-reliable data, it was shown that increasing the low-frequency amplification relative to the reference fitting led to a significant improvement in sound quality, while reducing the amplification worsened the sound quality. The results of this study phase are published on a preprint server: https://www.medrxiv.org/content/ In a second phase, the results from the first phase were to be verified under realistic conditions and using a real hearing aid. For this purpose, the manipulations used in the first phase were transferred to the fitting software of the hearing aid and a total of five different music samples were assessed using an A-B comparison. Here, the above described results obtained with the Master Hearing Aid were largely confirmed, although the changes in sound quality as a result of the parameter manipulations were relatively small. Overall, the study indicates that an increase in the low-frequency amplification compared to that proposed by the common DSL i/o, v. 5 rule leads to an improvement in the sound quality for music signals with bimodal cochlear implant fitting. References: Grimm, G., Herzke, T., Berg, D., & Hohmann, V. (2006). The master hearing aid: A PC-based platform for algorithm development and evaluation. Acta acustica united with Acustica, 92(4), 618-628. Scollie, S., Seewald, R., Cornelisse, L., Moodie, S., Bagatto, M., Laurnagaray, D., ... & Pumford, J. (2005). The desired sensation level multistage input/output algorithm. Trends in amplification, 9(4), 159-197