Perceptual Coherence : Hearing and Seeing

experience. Erickson (2003) found that when untrained listeners and choral
directors judged the similarity between sung vowels of classical singers,
the first two dimensions were identical: pitch and frequency of the spectral
centroid. The choral directors did, however, also use the vibrato frequency
to judge similarity.
I would argue that the lack of effect due to experience is due to the task
itself. Regardless of experience, all subjects were judging the difference in
terms of acoustic differences and not in terms of the source or musical implications.
Only two sounds were presented at one time, and the pairs were
presented in a random order. Listeners were instructed to judge the difference
between the sounds and not commit the stimulus error of judging the
difference between the sources. This outcome can be contrasted to the typical
results comparing untrained and trained listeners in tasks involving musical
tonality. In such tasks, untrained listeners make their judgments in
terms of the difference in pitch, while trained listeners make their judgments
in terms of the musical intervals. Thus, untrained listeners are treating
pitch and timbre differences acoustically, while explicit training allows
trained listeners to treat intervals as entities (Krumhansl, 2000).
The effect of musical training on identification and discrimination tasks
has also been small (e.g., Brown et al., 2001). Erickson, Perry, and Handel
(2001) found that experienced singers were only slightly more accurate in
detecting which of three vowels sung at different pitches was produced by
the “oddball” singer. Moreover, this difference disappeared when the range
in pitches exceeded one octave. In similar fashion, Lutfi, Oh, Storm, and
Alexander (2005) found no differences among practiced listeners, musicians,
and nonmusicians in distinguishing between actual and synthesized
impact sounds.
Timbre as a Source Variable
The Perception of Quality: Auditory Timbre 361
We would expect that there would be a close coupling between the physical
properties of objects and the acoustical properties of the resulting sounds
and that that coupling should enable the listener to identify the source. This
emphasis on identifying the source of a sound may result in different ways
of listening than when a subject is listening for the quality or the meaning
of the sound. Of course, the source itself can have inherent meaning: something
to run toward or run away from, for example.
Moreover, we would expect the context, the prior probabilities of different
sounds, higher-level cognitive factors such as memory and attention,
and individual differences among the listeners to be important factors in
determining the ability to identify the source. Although there seem to be
consistent acoustic properties that correlate with similarity judgments, this