Figure 3 Spectra for the four sounds used in Experiment II. The top two spectra represent the steady-state brass stimuli synthesized at notes C4 and C3. The bottom two spectra represent the steady-state flute stimuli synthesized at notes C4 and C5.

Listeners heard two notes that varied in instrument and/or in pitch interval. They were asked either to discriminate the instrument or identify the pitch interval on any given daily session. Each of the four listeners were tested over six 2 hr sessions. At the beginning of each session, and after every 48 experimental trials, a demonstration of four trials with answers was given to remind listeners of the task. Furthermore, the first session was designated practice for the instrument discrimination task, and the second session was practice for the pitch interval identification task. There were 10 runs of the experiment for each session, and the order of tasks over the six days was ABBAAB, where A was instrument identification, and B pitch interval discrimination. Knowledge of results was given to listeners after every experimental trial, and a summary of their performance was given to them after every run.