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- Ternström, Sten, 1956-
(författare)
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Hearing myself with others : sound levels in choral performance measured with separation of one's own voice from the rest of the choir.
- 1994
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Ingår i: Journal of Voice. - 0892-1997 .- 1873-4588. ; 8:4, s. 293-302
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Tidskriftsartikel (refereegranskat)abstract
- The choir singer has two acoustic signals to attend to: the sound of his or her own voice (feedback), and the sound of the rest of the choir (reference). The balance in loudness between feedback and reference is governed mainly by the room acoustics. Although earlier experiments have shown that singers have a fairly large tolerance for imbalance, with references ranging from -23 to +5 dB, experience suggests that, when singers are given control over this parameter, their preferences are much narrower. A quantification of the optimum balance would be useful in the design of concert stages and rehearsal halls. A method is described for measuring the feedback and reference levels as experienced by singers under live performance conditions. Recordings were made using binaural microphones worn by choir singer subjects. With the given combination of choir and room, it was possible to achieve adequate separation of the feedback and reference signals with simple signal processing. The feedback-to-reference ratio averaged over the 12 singers was found to be +3.9 dB, with extremes of +1.5 and +7.3 dB.
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- Ternström, Sten, 1956-
(författare)
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Perceptual evaluations of voice scatter in unison choir sounds.
- 1993
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Ingår i: Journal of Voice. - 0892-1997 .- 1873-4588. ; 7:2, s. 129-135
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Tidskriftsartikel (refereegranskat)abstract
- The preferences of experiences listerners for pitch and formant frequency dispersion in unison choir sounds were explored using synthesized stimuli. Two types of dispersion were investigated: (a) pitch scatter, which arises when voices in an ensemble exhibit small differences in mean fundamental frequency, and (b) spectral smear, defined as such dispersion of formants 3 to 5 as arises from differences in vocal tract length. Each stimulus represented a choir section of five bass, tenor, alto, or soprano voices, producing the vowel [u], [a], or [ae]. Subjects chose one dispersion level out of six available, selecting the "maximum tolerable" in a first run and the "preferred" in a second run. The listeners were very different in their tolerance for dispersion. Typical scatter choices were 14 cent standard deviation for "tolerable" and 0 or 5 cent for "preferred." The smear choices were less consistent; the standard deviations were 12 and 7%, respectively. In all modes of assessment, the largest dispersion was chosen for the vowel [u] on a bass tone. There was a vowel effect on the smear choices. The effects of voice category were not significant.
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- Ternström, Sten, 1956-
(författare)
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Physical and acoustic factors that interact with the singer to produce the choral sound
- 1991
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Ingår i: Journal of Voice. - : Elsevier. - 0892-1997 .- 1873-4588. ; 5:2, s. 128-143
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Tidskriftsartikel (refereegranskat)abstract
- Most of the people who perform music do so in the capacity of choir singers. An understanding of the particular acoustic properties of the choral sound is of interest not only to performers, but also to educators, architectural acousticians, audio technicians, and composers. The goal of choir acoustics is to describe various aspects of choral sound in acoustic terms, thereby taking into account the acoustics of voice production, the acoustics of rooms, and psychoacoustic properties of the auditory system. This article is an overview of choir acoustics research done in Stockholm over the past 8 years. It is an abridged and adapted version of an overview given in the author’s dissertation, Acoustical Aspects of Choir Singing. Three different kinds of experiments were made: (a) the control of phonation frequency and the vowel articulation of choir singers were investigated, by having individual choir singers perform vocal tasks on demand or in response to auditory stimuli; (b) typical values of sound levels, phonation frequency scatter, and long-time averaged spectra were obtained by measurements on choir singers rehearsing in ensemble under normal or near-normal conditions; and (c) models for certain aspects of choral sound were formulated and evaluated by synthesis. The choir singer’s performance is based on two acoustic signals: her or his own voice (the feedback) and the rest of the choir (the reference). Intonation errors were found to be induced or increased by (a) large level differences between the feedback and the reference, (b) several perceptually unfavorable spectral properties of the reference, and (c) articulatory maneuvers, i.e., intrinsic pitch. The magnitude of the errors would be indirectly related to room acoustics (a and b) and to voice usage and musical/textual content (b and c). When singing alone, singers from one choir used a vowel articulation that was different from that in speech and also more unified; it was also in some respects different from solo singing. Long-time average spectrum effects of room acoustics and musical dynamics were large, as expected; those of choir type and musical material were smaller. To some extent, choirs adapted their sound level and voice usage to the room acoustics. Small random fluctuations in phonation frequency, called "€œflutter"€ and "€œwow,"€ are always present in human voices. With multiple voices, flutter and wow cause, through interference, a pseudorandom, independent amplitude modulation of partial tones, which is known to cue the perceptual "€œchorus effect." The chorus effect is also influenced by the reverberation properties of the room. Choral sounds were explored by means of synthesis, and the importance of realistic flutter was established. Flutter in choir singers was analyzed and simulated in single synthesized voices. Expert listeners were unable to discriminate between simulated and authentic flutter.
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