Hypersignal analyses of orchestral instrument signals as correlated with perception of timbre Free

Experiments were conducted to assess the relationships among signal analyses and timbral perception across the playing range of bassoon, trombone, tenor saxophone, alto saxophone, soprano saxophone, French horn, violin, oboe, flute, clarinet, and trumpet. Spectral analyses employed Hypersignal using 9th order Zoom FFT on 22.05 samples/s signals. Spectral centroid and spectral flux measures were calculated. Perceptual experiments included similarity scaling and identification at various pitch chroma across the playing range of the instruments. In addition, a pilot experiment assessing the interaction of pitch chroma and timbre was conducted where timbral judgements were made across, rather than within, pitch chroma. Results suggest that instruments with relatively low tessitura produce higher centroid ranges since the larger air column yeilds a large number of vibrational modes. In contrast, higher tessitura instruments, using smaller air columns, produce fewer modes of vibration with increasing pitch chroma, to the point that the centroids coverge near Bb5. Perceptual data correspond to the spectral, resulting in less specificity among instruments at their higher tessituras. It is suggested that spectral centroid, which maps strongly near A4 in the majority of studies, must be viewed with caution as a predictor of timbre at tessitura extremes.