[Influence of overtones and undertones on melody recognition with a cochlear implant with SSD]

Many cochlear implant (CI) users have difficulties recognising pitches and melodies because pitch transmission is blurred and shifted. This study investigates whether postlingually deafened adult CI users recognize melodies better when overtones are removed or undertones are added.Fifteen unilaterally postlingually deafened CI users (single sided deafness = SSD) were included aged 22 to 73 years (MW 52, SD 11.6) with CI hearing experience between 3 and 75 months (MW 33, SD 21.0) with varying MED-EL devices. Three short piano melodies were presented to them firstly to the normal-hearing ear and then in modified overtone or undertone variants and the original variant to the CI ear. These variants should be identified as one of the three original melodies. In addition, musical experience and ability were assessed by the Munich Music Questionnaire and the MiniPROMS music tests.The CI users showed the best melody recognition in the fundamental frequency variant. The overtone variant with the third overtone was as good as the original variant with all overtones with regard to melody recognition (p=1). However, the undertone variant with the first undertone was recognised significantly worse than the fundamental version (p=0.032). Furthermore, there was no correlation between musical experience or musical ability and the number of melodies recognised (p>0.1).Since a reduction of overtones did not worsen the melody recognition, overtone reduction should be considered in future music processing programs for the CI. This could reduce the energy consumption of the CI.