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Detection of frequency changes in transposed sequences of tones
1Department of Speech and Hearing Sciences, Indiana University, Bloomington 47405, USA.
The Journal of the Acoustical Society of America
|January 1, 1996
Summary
Detecting frequency changes in transposed tone sequences is harder than in non-transposed ones. This difficulty in frequency discrimination increases with transposition but is influenced by pattern complexity and uncertainty.
Area of Science:
- Auditory Perception
- Psychoacoustics
- Cognitive Psychology
Background:
- Auditory perception research often investigates the discrimination of simple tones.
- Understanding how listeners process complex sequences, especially with frequency shifts, is crucial for auditory scene analysis.
Purpose of the Study:
- To investigate the impact of transposition (frequency shifting) on the ability to detect changes in relative frequencies within tone sequences.
- To examine how pattern complexity (number of tones) and uncertainty affect frequency discrimination thresholds in transposed patterns.
Main Methods:
- Seven experiments were conducted using five-tone and two-tone patterns.
- Listeners judged which of two transposed comparison patterns matched the relative frequencies of a standard pattern.
- Experiments varied pattern length and uncertainty levels (high vs. minimal).
Main Results:
- Frequency discrimination thresholds were significantly higher for transposed patterns compared to non-transposed ones, irrespective of pattern length or uncertainty.
- Performance tended to degrade with increased transposition, particularly under high uncertainty, with most effects seen within two semitones.
- Minimal uncertainty greatly improved performance for five-tone patterns but had no effect on two-tone patterns.
- Thresholds for two-tone patterns were comparable to five-tone patterns under minimal uncertainty.
Conclusions:
- Transposition significantly impairs relative frequency discrimination, similar to its effects on absolute frequency discrimination.
- Stimulus complexity and pattern familiarity (uncertainty) similarly influence both absolute and relative frequency discrimination in auditory sequences.