Effects of asynchrony and ear of presentation on the pitch of mistuned partials in harmonic and frequency-shifted complex tones

Abstract

When a partial of a periodic complex is mistuned, its change in pitch is greater than expected. Two experiments examined whether these partial-pitch shifts are related to the computation of global pitch. In experiment 1, stimuli were either harmonic or frequency-shifted (25% of F0) complexes. One partial was mistuned by +/- 4% and played with leading and lagging portions of 500 ms each, relative to the other components (1 s), in both monaural and dichotic contexts. Subjects indicated whether the mistuned partial was higher or lower in pitch when concurrent with the other components. Responses were positively correlated with the direction of mistuning in all conditions. In experiment 2, stimuli from each condition were compared with synchronous equivalents. Subjects matched a pure tone to the pitch of the mistuned partial (component 4). The results showed that partial-pitch shifts are not reduced in size by asynchrony. Similar asynchronies are known to produce a near-exclusion of a mistuned partial from the global-pitch computation. This mismatch indicates that global and partial pitch are derived from different processes. The similarity of the partial-pitch shifts observed for harmonic and frequency-shifted stimuli suggests that they arise from a grouping mechanism that is sensitive to spectral regularity.

Grouping and the pitch of a mistuned fundamental component: Effects of applying simultaneous multiple mistunings to the other harmonics

“…As noted earlier, the partial-pitch shifts produced by mistuning a component in a complex tone are associated with spectral grouping rather than with global-pitch perception (see Roberts, 2005). In particular, a mistuned component typically shows a pitch shift in the direction of mistuning whether the spectral frame is harmonic or frequency shifted Brunstrom and Roberts, 2001). However, for harmonic relations and random perturbations from it, the magnitude of the pitch-shift gradient associated with the F0 component is strongly correlated with the strength of the periodicity cue corresponding to the F0 frequency.…”

“…In these cases, the effect of mistuning a component from its original frequency (as defined by the shift or stretch transformation) has also been found typically to increase its salience and to produce a partialpitch shift in the direction of the mistuning (Roberts andBrunstrom, 1998, 2001;Brunstrom and Roberts, 2001). Furthermore, the global pitches evoked by frequencyshifted stimuli cannot account for the grouping of their components (Brunstrom and Roberts, 2000;Roberts and Brunstrom, 2003).…”

Pitch, harmonicity and concurrent sound segregation: Psychoacoustical and neurophysiological findings

“…If the amount of mistuning exceeds 1–2%, the mistuned harmonic usually “pops out” from the complex, and is heard as separate tone (Brunstrom and Roberts, 2001; Hartmann et al, 1986; Hartmann et al, 1990; Lin and Hartmann, 1998; Moore et al, 1986; Roberts and Brunstrom, 1998; Roberts and Holmes, 2006). However, the mistuned harmonic continues to contribute to the pitch of the complex for mistunings of up to 3% (Darwin et al, 1994; Moore et al, 1985).…”

Envelope Processing and Sound-Source Perception

“…Results from a number of studies show that the ability to detect change in a target component of a complex is at times either unaffected or impaired by gating asynchrony. These include studies of identification thresholds of masked signals (Gordon 2000), pitch processing (Carlyon 1994;Brunstrom and Roberts 2001), and profile analysis (Green and Dai 1992;Hill and Bailey 1997;Lentz et al 2004). Though the independent variable in all cases was some characteristic of the target component, task performance was influenced by cross-spectral processing between the target and remaining (nontarget) stimulus components.…”