Abstrocti It is unclar whether or not the perceptual~gregation of a mistuned harmonic from a periodic complex tone depends sFificallY on harmonic relations kmeen the other partials. A matching procedure used previously for harmonic complexes (1) was adapted and extended to regular inharmonic complexes. Near matches to the mistuned partial, indicating segregation, were almost as frequent in the inharmonic conditions as in the harmonic case. Mso, small but consistent mismatches, pitch shifis, were found in all conditions, These were similar in direction and size 10earlier findings for harmonic complexes. The results sup~rt the propsst that aspects of s~ctral regularity other than harmonic relations alone can affect auditory grouping,
BACKGROWThe percepti segregation of a rnistund partial from a harmonic complex tone has ofien been reported, In one study, listeners were asked to adjust the frequency of a pure tone until it matched that of a mistuned partial in an otherwise harmonic complex (1). Mistuned partials up to at least the 12th could be matched successfully. Small but systematic mismatches between the frequency of the mistuned partial and the preferred frequency of the pure tone were found. These "pitch shifis" were generally exaggerations of the mistuning imposed on a partial, It has since been proposed (2) that these pitch shifts can be ex~lained in terms of the operation of a template mechanism on a set of partials whose internal representation is affected by random processes (neural noise). For a template aligned optimally with the harmonic partials, occasions when the frequency of the mistuned partial is represented as more displaced from the center of a "slot" in the template will lead to greater segregation, and hence to more "hits'.. From this, it follows that rnistunings in either direction will lead to pitch estimates displaced ouhvards from the slot center. This account could in principle generalize to any arbitr~template, whether harmonic or not (2).Aspects of spectral pattetig other than harrnonicity can also affect audito~grouping. For example, a single even harmonic in an otherwise odd-harmonic complex is typically judged as more salient than its odd neighbors (3), This finding has since been extended to regular but inharmonic complexes, created by applying either frequency shifi or pkd stretch manipulations to harmonic stimuli (4), It has been suggested that these findings indicate the operation of a principle of audito~~ouping based on common spectral pattern. This proposal is investigated here,
H STUDYOn each trial, subjects heard the following sounds in a continuous loop: 12-component complex tone (420 ms)s ilence (200 ms)~pure tone (310 ms) + silence (500 ins). A mistuning of +/-4°/0 was applied to one of the components 2-11, The complexes for conditions 1-3 were harmonic, 15% frequency shfied, and 3% spectrally stretched, respectively (see Table 1). The nominal tidarnental frequency used was 200 W, roved in the range +/-10"/O. Subjeets adjusted the pure tone to match the pitch of the mi...
