When speech enhances Spatial Musical Association of Response Codes: Joint spatial associations of pitch and timbre in nonmusicians

Previous studies have shown that the effect of the Spatial Musical Association of Response Codes (SMARC) depends on various features, such as task conditions (whether pitch height is implicit or explicit), response dimension (horizontal vs. vertical), presence or absence of a reference tone, and former musical training of the participants. In the present study, we investigated the effects of pitch range and timbre: in particular, how timbre (piano vs. vocal) contributes to the horizontal and vertical SMARC effect in nonmusicians under varied pitch range conditions. Nonmusicians performed a timbre judgement task in which the pitch range was either small (6 or 8 semitone steps) or large (9 or 12 semitone steps) in a horizontal and a vertical response setting. For piano sounds, SMARC effects were observed in all conditions. For the vocal sounds, in contrast, SMARC effects depended on pitch range. We concluded that the occurrence of the SMARC effect, especially in horizontal response settings, depends on the interaction of the timbre (vocal and piano) and pitch range if vocal and instrumental sounds are combined in one experiment: the human voice enhances the attention, both to the vocal and the instrumental sounds.