Perceptual and Acoustical Features of Natural and Synthetic Orchestral Instrument Tones

Four experiments were conducted to explore the timbres of natural, continuant orchestral instruments with emulation based on sampling, frequency modulation ( FM) synthesis, and a hybrid consisting of sampling and synthesis techniques combined. Identification of instruments using verbal labels was significantly better for the natural and sampling- based signals than for either FM synthesis or the hybrid technique, a result also found for aural categorization. Perceptual scaling of timbral similarities demonstrated great consistency across a series of independent variables, including musical training, monophonic and stereo presentation, and long versus short signal durations. The first dimension of the classical multidimensional scaling (CMDS) solutions mapped onto long- time- average spectral centroid. The second dimension mapped onto a measure of spectral variability. Little evidence was found for the mapping of attack time or signal duration onto either dimension. A third dimension separated most natural instruments from their emulated counterparts. Experiments using verbal attribute ratings confirmed the correlation of spectral centroid, the first dimension of the perceptual space, and ratings of nasality; the second dimension correlated with spectral variability and modestly correlated with ratings of rich, brilliant, and tremulous. Mismatches of spectral distribution and variability resulted in poor emulations of the natural instruments. Results suggest that further study of centroid and time-variant psychophysical properties is warranted.

Verbal Attributes of Simultaneous Wind Instrument Timbres: II. Adjectives Induced from Piston's "Orchestration"

Experiments were conducted to explore the relationship between wind instrument dyad timbres and verbal attributes drawn from the musicological literature in order to compare and contrast results with studies using artificial stimuli and amusical rating scales. In the first experiment, all adjectives in Piston's (1955) "Orchestration" were collated and subsequently reduced to 61 examples. A checklist procedure was used in response to the dyad timbres to further reduce the set of adjectives to 21. The 21 adjectives were used in verbal attribute magnitude estimation of the 10 wind instrument dyad timbres. Principal components analysis of ratings revealed four verbal attribute factors, accounting for 90.604% of the variance: power, strident, plangent, and reed. Correlational analyses demonstrated an improvement in mapping between the ratings and perceptual similarity spaces over the procedure used in Part I of this study. The two-dimensional timbral circumplex was interpreted as having a principal dimension of nasality versus richness and a secondary dimension of reediness versus brilliance.

The Influence of Duration on Verbal-Attribute Ratings of Complex Protomusical Sounds

Based on natural spectra, 7 different complex sounds were synthesized digitally, each in a long version (3 s in duration) and in a short version (0.5 s in duration) for a total of 14 sounds. These stimuli were presented to 34 subjects who rated each sound on each of 12 seven-point verbal scales. A rating was defined as an emotional response. Based on previous work, mutually exclusive subsets of the emotional responses to four scales were assigned to each of three verbal dimensions or factors, the Factors were: I, Tension–Relaxation; II, Lightheartedness–Gloom; and III, Attraction–Repulsion. By means of analysis-of-variance methods it was found that the sounds evoked divergent emotional responses with respect to all three factors and that the emotional responses to shortduration sounds were similar to those to long-duration sounds. Only for Factor II was there a significant interaction, in that two of the short sounds were rated more lighthearted than the two corresponding long sounds. Otherwise it appears that emotional responses to the short sounds did not differ from those to their corresponding long sounds, as measured by mean ratings. Because the responses to given short versions or long versions of the complex sounds were essentially the same, it may be concluded that the short versions contain considerable information, and the two versions are therefore substitutable for each other as experimental stimuli. Another implication is that even very brief complex sounds can elicit emotional ratings of the kind defined here.

Verbal Attributes of Simultaneous Wind Instrument Timbres: I. von Bismarck's Adjectives

A study on the verbal attributes of timbre was conducted in an effort to interpret the dimensional configuration of the similarity spaces of simultaneously sounding wind instrument timbres. In the first experiment, subjects rated 10 wind instrument dyads on eight factorially pure semantic differentials from von Bismarck's (1974a) experiments. Results showed that the semantic differentials failed to differentiate among the 10 timbres. The semantic differential methodology was changed to verbal attribute magnitude estimation (VAME), in which a timbre is assigned an amount of a given attribute. This procedure resulted in better differentiation among the 10 timbres, the first factor including attributes such as heavy, hard, and loud, the second factor involving sharp and complex, a contrast with von Bismarck's results. Results of the VAME analysis separated alto saxophone dyads from all others, but mapped only moderately well onto the perceptual similarity spaces. It was suggested that many of the von Bismarck adjectives lacked ecological validity.

Perceptual Scaling of Simultaneous Wind Instrument Timbres

Timbral similarities among wind instrument duos were studied. Flute, oboe, E♭ alto saxophone, B♭ clarinet, and B♭ trumpet instrumentalists performed in all possible duo pairings (dyads). Source material included B♭4 unisons, unison melody, major thirds, and harmonized melody. Nonunison combinations had each instrument of the pair as the soprano, creating a total of six contexts. Music major and nonmusic major subjects rated the similarity of all possible pairs of dyads in each of the six contexts. Classical multidimensional scaling (MDS) was performed; contexts were treated as " subjects" in an individual differences scaling (INDSCAL) analysis of composite data. The resulting spaces had two stable, interpretable dimensions. From verbal attribute rating experiments ( Kendall & Carterette, in preparation, a), these were identified as " nasal" vs. " not nasal," and " rich" vs. " brilliant." A third dimension was interpreted as "simple" vs. "complex."Extrema in the space were associated with three of the five instruments: Trumpet (brilliant), saxophone (rich), and oboe ( nasal). Data that were amalgamated over contexts and plotted in two dimensions yielded a circumplicial configuration. Implications for orchestration are discussed and a theoretical model of timbre combinations and groupings is presented.