Bimodal Benefit for Music Perception and Appreciation: Effect of acoustic bandwidth and resolution of low-frequency acoustic stimuli
D'Onofrio, Kristen Leigh
Previous literature has examined the effect of acoustic bandwidth on bimodal benefit for speech recognition (e.g., Zhang et al., 2010; Sheffield & Gifford, 2014). The current study extends this earlier work to examine the effect of acoustic bandwidth for music perception and appreciation. The primary aims were two-fold: (1) to determine the minimum and optimum acoustic bandwidth necessary to obtain bimodal benefit for music perception, music appreciation, and speech perception, and (2) to determine whether optimal acoustic bandwidth is correlated with resolution of acoustic, low-frequency stimuli via behavioral (pitch discrimination) and objective (FFR) measures. Acoustic stimuli were presented to the non-CI ear in the following filter conditions: < 125, < 250, < 500, < 750 Hz, and wideband (full bandwidth). Music and speech perception for all filter conditions were assessed via measures of timbre perception, musical sound quality, and monosyllabic word recognition. The fundamental frequencies (F0) tested via pitch discrimination and FFR were music notes from the Western tonal system closest to the low-pass filter cutoffs used for music and speech perception testing, including: B2 (123 Hz), B3 (247 Hz), B4 (494 Hz), and F#5 (740 Hz). Generally, performance for all stimuli improved with increasing acoustic bandwidth; however, the bandwidth that is both minimally and optimally beneficial may be dependent upon stimulus type. On average, speech recognition required a smaller acoustic bandwidth (< 250 Hz) for significant benefit, whereas musical sound quality required wideband amplification. Our results did not indicate a relationship between bimodal benefit and pitch discrimination or neural representation of F0 via FFR. Further research is warranted to investigate optimal acoustic bandwidth for additional stimulus types; however, a shift toward a more personalized fitting approach for the acoustic hearing ear may be an important clinical consideration.