Identification and discrimination of sweep formants

Area of Science:

• Auditory perception
• Acoustics
• Psychoacoustics

Background:

• Previous research indicated a tendency to perceive steady and slightly rising tones as falling.
• Auditory perception experiments often use simple tonal stimuli.

Purpose of the Study:

• To investigate auditory perception of more complex frequency sweeps.
• To determine how stimulus complexity affects the perception of rising and falling tones.
• To analyze the factors influencing sweep discrimination.

Main Methods:

• Experiments replicated earlier sweep tone identification tasks using rising and falling single formant sweeps.
• Stimuli varied in duration (15-40 msec) and sweep rate (0-40 oct/sec).
• Steady-state portions (100 msec) were added to the sweeps.

Main Results:

• The tendency to misperceive level and slightly rising tones as falling diminished with increased stimulus complexity.
• Sweep discrimination was found to be dependent on the initial and final frequencies of the sweep.
• More complex sweeps led to more accurate pitch contour perception.

Conclusions:

• Auditory perception of frequency sweeps is influenced by stimulus complexity.
• The initial and final frequencies are critical determinants for discriminating sweep direction.
• Complex auditory stimuli alter fundamental aspects of pitch perception.