Acoustic foundations of the speech-to-song illusion.

Abstract

In the "speech-to-song illusion", certain spoken phrases are heard as highly song-like when isolated from context and repeated. This phenomenon occurs to a greater degree for some stimuli than for others, suggesting that particular cues prompt listeners to perceive a spoken phrase as song. Here we investigated the nature of these cues across four experiments. In Experiment 1, participants were asked to rate how song-like spoken phrases were after each of eight repetitions. Initial ratings were correlated with the consistency of an underlying beat and within-syllable pitch slope, while rating change was linked to beat consistency, within-syllable pitch slope, and melodic structure. In Experiment 2, the within-syllable pitch slope of the stimuli was manipulated, and this manipulation changed the extent to which participants heard certain stimuli as more musical than others. In Experiment 3, the extent to which the pitch sequences of a phrase fit a computational model of melodic structure was altered, but this manipulation did not have a significant effect on musicality ratings. In Experiment 4, the consistency of inter-syllable timing was manipulated, but this manipulation did not have an effect on the change in perceived musicality after repetition. Our methods provide a new way of studying the causal role of specific acoustic features in the speech-tosong illusion via subtle acoustic manipulations of speech, and show that listeners can rapidly (and implicitly) assess the degree to which non-musical stimuli contain musical structure.

Spontaneous Production Rates in Music and Speech

“…Second, we had participants produce these phrases many times in a cyclical fashion (Cummins and Port, 1998) and we measured spontaneous rate by aggregating across these repetitions. Recent research suggests that the repetition of speech causes listeners to perceive more song-like qualities (Deutsch et al, 2011;Tierney et al, 2013Tierney et al, , 2018Falk et al, 2014;Vanden Bosch der Nederlanden et al, 2015). We hypothesized that repeated productions may lead to SPRs more similar to those in music performance tasks.…”

Individual Differences in Perception of the Speech-to-Song Illusion are Linked to Musical Aptitude but not Musical Experience

“…Falk, Rathcke, & Dalla Bella (2014) manipulated the stability of pitch contours within syllables and found that song percepts were more common for the more stable contours. Tierney et al (2018b) found that higher song ratings for song illusion stimuli were linked to more isochronous rhythmic structure and a greater tendency for syllable pitches to follow musical melodic statistics. Rathcke, Falk, & Dalla Bella (in press) found that recordings with greater sonority led to earlier and stronger transformations to song.…”

“…(2015a), Tierney et al (2018a), and Tierney et al (2018b). Second, several studies have demonstrated that a range of acoustic and musical stimulus characteristics modulate the strength of the illusion.…”

“…To this end, we used the same set of illusion and control stimuli and testing methods employed in our previous research on the song illusion (Tierney et al, 2013;2018b). Our first research question was whether this paradigm can elicit stable individual differences in the strength of perception of the illusion across individuals.…”

Does age affect perception of the Speech-to-Song Illusion?

“…An increasing number of studies have used a variety of stimuli to examine various aspects of the Speech-to-Song Illusion, making this illusion a well-established perceptual phenomenon [16][17][18][19][20][21][22][23][24]. To provide a strong test of our age-related hypothesis about the Speech-to-Song Illusion, we attempted to maximize the likelihood that listeners would experience the Speech-to-Song Illusion by using the original stimulus recorded by [25], rather than the variety of stimuli that have been used previously [e.g., 1,8].…”