Reduction of the Harmonic Series Influences Musical Enjoyment With Cochlear Implants.

OBJECTIVE: Cochlear implantation is associated with poor music perception and enjoyment. Reducing music complexity has been shown to enhance music enjoyment in cochlear implant (CI) recipients. In this study, we assess the impact of harmonic series reduction on music enjoyment. STUDY DESIGN: Prospective analysis of music enjoyment in normal-hearing (NH) individuals and CI recipients. SETTING: Single tertiary academic medical center. PATIENTS: NH adults (N = 20) and CI users (N = 8) rated the Happy Birthday song on three validated enjoyment modalities-musicality, pleasantness, and naturalness. INTERVENTION: Subjective rating of music excerpts. MAIN OUTCOME MEASURES: Participants listened to seven different instruments play the melody, each with five levels of harmonic reduction (Full, F3+F2+F1+F0, F2+F1+F0, F1+F0, F0). NH participants listened to the segments both with and without CI simulation. Linear mixed effect models (LME) and likelihood ratio tests were used to assess the impact of harmonic reduction on enjoyment. RESULTS: NH listeners without simulation rated segments with the first four harmonics (F3+F2+F1+F0) most pleasant and natural (p <0.001, p = 0.004). NH listeners with simulation rated the first harmonic alone (F0) most pleasant and natural (p <0.001, p = 0.003). Their ratings demonstrated a positive linear relationship between harmonic reduction and both pleasantness (slope estimate = 0.030, SE = 0.004, p <0.001, LME) and naturalness (slope estimate = 0.012, SE = 0.003, p = 0.003, LME). CI recipients also found the first harmonic alone (F0) to be most pleasant (p = 0.003), with a positive linear relationship between harmonic reduction and pleasantness (slope estimate = 0.029, SE = 0.008, p <0.001, LME). CONCLUSION: Harmonic series reduction increases music enjoyment in CI and NH individuals with or without CI simulation. Therefore, minimization of the harmonics may be a useful strategy for enhancing musical enjoyment among both NH and CI listeners.

Reverberation time influences musical enjoyment with cochlear implants.

OBJECTIVE: To identify factors that enhance the enjoyment of music in cochlear implant (CI) recipients. Specifically, we assessed the hypothesis that variations in reverberation time (RT60) may be linked to variations in the level of musical enjoyment in CI users. STUDY DESIGN: Prospective analysis of music enjoyment in normal-hearing individuals. SETTING: Single tertiary academic medical center. PATIENTS: Normal-hearing adults (N = 20) were asked to rate a novel 20-second melody on three enjoyment modalities: musicality, pleasantness, and naturalness. INTERVENTION: Subjective rating of music excerpts. MAIN OUTCOME MEASURES: Participants listened to seven different instruments play the melody, each with five levels (0.2, 1.6, 3.0, 5.0, 10.0 s) of RT60, both with and without CI simulation processing. Linear regression analysis with analysis of variance was used to assess the impact of RT60 on music enjoyment. RESULTS: Without CI simulation, music samples with RT60 = 3.0 seconds were ranked most pleasant and most musical, whereas those with RT60 = 1.6 seconds and RT60 = 3.0 seconds were ranked equally most natural (all p < 0.05). With CI simulation, music samples with RT60 = 0.2 seconds were ranked most pleasant, most musical, and most natural (all p < 0.05). Samples without CI simulation show a preference for middle-range RT60, whereas samples with CI simulation show a negative linear relationship between RT60 and musical enjoyment, with preference for minimal reverberation. CONCLUSION: Minimization of RT60 may be a useful strategy for increasing musical enjoyment under CI conditions, both in altering existing music as well as in composition of new music.