Auditory Effect of Perturbing Musical Tones by Interpolation with Other Music Tones

The effect of blending variable amounts of a secondary tone with a primary tone by means of interpolating between their corresponding harmonic amplitudes was investigated. Original tones(bassoon,clarinet,flute,horn,oboe,altosaxophone,trumpet, and violin) were normalized with respect to fundamental frequency, duration, attack and decay times, and loudness; also, harmonic frequencies were flattened. However, the basic time variations of the tones' harmonic amplitudes were preserved. Interpolation was accomplished in the frequency domain using interpolation levels between 5 and 50%. While the effect of perturbation is highly dependent on the primary/secondary instrument pair, results show that the effect of a secondary instrument is heard most easily for primary instruments horn and bassoon and least easily for primary instruments trumpet and saxophone. On the other hand, clarinet and trumpet are heard most easily as secondary instruments, whereas bassoon and violin are slow to be heard. Discrimination scores were correlated with different spectrotemporal measures of the tone spectra: spectral incoherence, normalized spectral centroid deviation, and spectral irregularity. The only significant effect found was that primary instruments with high spectral incoherence tend to mitigate against perturbation by secondary instruments. [Work supported by Research Grants Council Grants 613806 and 613508.