• Volume/Page
  • Keyword
  • DOI
  • Citation
  • Advanced
   
 
 
 

Journal of the Acoustical Society of America

SECTION LISTING

BROWSE VOLUMES

Year Range: 
Search Issue | RSS Feeds RSS
Previous Issue Next Issue

Nov 1979

Volume 66, Issue S1, pp. S1-S89

Return to All Sections
back to top
RSS Feeds
back to top Session O. Musical Acoustics II: General Musical Acoustics
Contributed Papers
FREE

Radiation fields of a violin in the region of the Helmholtz and main body resonances (A)

Gabriel Weinreich and Eric B. Arnold

J. Acoust. Soc. Am. Volume 66, Issue S1, pp. S29-S29 (1979); (1 page)

Online Publication Date: 11 Aug 2005

Full Text: | Download PDF

Show Abstract
The measuring system previously described [G. Weinreich and E. B. Arnold, J. Acoust. Soc. Am. Suppl. 1 65, S72(A) (1979)] has been used to analyze the acoustic fields radiated by a violin in the frequency range of the Helmholtz and main body resonances. The violin is driven electrodynamically by an ac current through the string and a permanent magnet mounted over it. The frequency of the driving oscillator is locked to the string resonance by a feedback loop actuated by an acceleration sensor at the bass foot of the bridge, and is adjusted by moving a small Delrin mass which slides on the string, so that the tension maintains its normal value. Observations at the Helmholtz resonance include the nearfield motion of air through the f holes, which is otherwise difficult to see, and the resulting farfield pattern. Because of the 90° relative phase shift between the s wave and p wave as one moves from the nearfield to the farfield, the nearfield pattern, with its strong motion in the forward direction, becomes completely bidirectional in the farfield. [Work supported by NSF.]
FREE

Calibration procedure and error analysis for a violin radiation measuring system (A)

Eric B. Arnold and Gabriel Weinreich

J. Acoust. Soc. Am. Volume 66, Issue S1, pp. S30-S30 (1979); (1 page)

Online Publication Date: 11 Aug 2005

Full Text: | Download PDF

Show Abstract
The system referred to in the preceding paper involves measurement of acoustic pressure, both in amplitude and in phase, on two concentric spheres of known radii. Among possible sources of error are: the finite number of measurements; inaccuracy in microphone positioning; scattering by the moving boom system; electrical and acoustical noise in the microphone system; spurious phase shifts and gain inequalities in the microphone and amplifier channels; timing errors and overtone sensitivity of the phase‐sensitive detectors; offsets and quantizing errors in the analog‐to‐digital converter; and numerical computation errors. Effects due to the nonideal nature of the anechoic chamber are in a different category, since our system measures the reflected wave directory. [Work supported by NSF.]
FREE

Measured reproducibility of clarinet spectra (A)

A. H. Benade and C. O. Larson

J. Acoust. Soc. Am. Volume 66, Issue S1, pp. S30-S30 (1979); (1 page)

Online Publication Date: 11 Aug 2005

Full Text: | Download PDF

Show Abstract
Published spectra show little consistency beyond a tendency toward strong odd partials. Neglect of radiation pattern and wave‐statistics fluctuations in rooms, join with inadequate specification of the player's task to cause this variability. We have studied 0.5 s alternating C4, D4 tones lasting about 35‐s total at mezzoforte level (reed just beginning to beat), played on six clarinets, A, B♭ (three), C, E♭ All instruments were optimized to similar criteria over the past decade by one of us (AHB) who also made each its own mouthpiece (the bores were dissimilar). The instruments all have been used by major players. The player (AHB) walked about while playing (0.75 m/s), as did the two persons carrying the recording microphones, in a room V = 8000m3, T60 = 1.2 s. Source and mike position changes, plus mode perturbation effects from three people, assure the equivalent of at least 75 statistically independent data points for each component of each tone. The SPL for the first five harmonics averaged over all twelve tones are 50, 22.6, 48.8, 27.0, 48.3 dB (σ = 2 dB). Room fluctuations are within ±1 dB (95% confidence). Most of the remaining variation comes from interinstrument differences and not player/instrument instabilities. These results are consistent with a preliminary experiment analyzed by Karla Brasaemle. [Work assisted by NSF.]
FREE

A functional model of a simplified clarinet (A)

S. E. Stewart and W. J. Strong

J. Acoust. Soc. Am. Volume 66, Issue S1, pp. S30-S30 (1979); (1 page)

Online Publication Date: 11 Aug 2005

Full Text: | Download PDF

Show Abstract
A functional model (computer simulation) of a simplified clarinet has been implemented on a digital computer. The simplified clarinet consists of a standard clarinet mouthpiece and reed attached to a straight cylindrical tube without tone holes. The tube and mouthpiece are represented in the model by a lumped element approximation to a transmission line. Application of Kirchoff's circuit laws to this circuit gives a coupled set of differential equations which were solved numerically on a digital computer to yield volume velocities and pressures in the mouthpiece and tube. The pressure in the mouthpiece drives the reed which is represented in the model as a tapered bar clamped at one end. The partial differential equation describing vibrations of such a bar was solved numerically to obtain the size and shape of the reed aperture. The reed aperture area governs the volume velocity into the tube which in turn drives the air column vibrations. The model exhibits self‐sustained oscillations, threshold blowing pressures, and “lipping” of the tone. The spectra of the mouthpiece and radiated pressures are in general agreement with actual clarinet spectra. Some interesting features of the model are the inclusion of a frequency‐dependent viscous loss in the tube and a dependence of the aperture volume velocity on the initial or rest opening of the aperture.
FREE

Temperature‐induced length and tension variations affecting the pitch of a stretched string (A)

Robert E. Kelly

J. Acoust. Soc. Am. Volume 66, Issue S1, pp. S30-S30 (1979); (1 page)

Online Publication Date: 11 Aug 2005

Full Text: | Download PDF

Show Abstract
The pitch variation of a stretched string is analyzed in terms of length and tension perturbations caused by temperature. In particular, it is shown that tension changes due to differential expansion between the string and its frame usually dominate the effects caused by an explicit length deviation. Numerical examples are given for various combinations of string and frame compositions. The corresponding problem for the wind instruments is briefly considered, including the typical viewpoint of performing musicians.
FREE

Contrasting sounds in the upper male voice (A)

Lloyd A. Smith

J. Acoust. Soc. Am. Volume 66, Issue S1, pp. S30-S30 (1979); (1 page)

Online Publication Date: 11 Aug 2005

Full Text: | Download PDF

Show Abstract
Four sounds were contrasted in the upper male voice. The sounds were identified as follows: (1) falsetto; (2) head tone; (3) pharyngeal voice; (4) operatic head voice. All sounds were sung by a tenor on the vowel /a/ at a pitch level of A4, 415 Hz. Spectrographic analyses were performed to determine what physiological relationships might be inferred among the sounds. The length of time the singer was able to sustain each sound was tested in order to gain information concerning the relative air flows. The results show that the pharyngeal voice and operatic voice have much more energy in the high partials and have much lower rate of air flow. This evidence indicates that these two sounds are characterized by much more complete closure of the glottis than is exhibited in the other two sounds. It is concluded that the four sounds are produced by only two different laryngeal adjustments. Acoustical differences accounting for differentiation of sounds produced by the same laryngeal setting are discussed. A recommendation is made concerning the pedagogical use of registers and suggestions are made for further research.
FREE

The effect of envelope on fusion of tones with inharmonic partials (A)

Elizabeth Cohen

J. Acoust. Soc. Am. Volume 66, Issue S1, pp. S30-S30 (1979); (1 page)

Online Publication Date: 11 Aug 2005

Full Text: | Download PDF

Show Abstract
Temporal envelopes for tones with an inharmonic partial structure were generated using the Systems Concepts Digital synthesizer. [E. Cohen, J. Acoust. Soc. Am. Suppl. 1, 65, S123(A) (1979)]. The reasons for choosing envelopes based on musical viability rather than a flat “psychoacoustically standard” pattern, will be discussed. Subjects were asked to make judgments on the degree of tone dispersion for single tones differing in degree of inharmonicity and temporal envelope. The importance of attack and decay times, as well as transients in the signal will be explained. A real‐time experiment on the determination of subjective interval size of dyads using two different envelope patterns also revealed that duration of the “steady state” portion of signal has an effect on tone fusion.
FREE

Optional modules for a flexible musical acoustics course (A)

Donald E. Hall

J. Acoust. Soc. Am. Volume 66, Issue S1, pp. S30-S31 (1979); (2 pages)

Online Publication Date: 11 Aug 2005

Full Text: | Download PDF

Show Abstract
Musical acoustics courses draw students with a wide range of backgrounds, from nonmusicians to graduate music majors. Within either group there is a variety of topical interests—one instrument or another, room acoustics, hi‐fi, harmonic theory, perception, etc. To meet the needs of such a diverse group, I have been offering a course with a spiral organization that branches into roughly a dozen optional modules, of which each student is to choose two or three for detailed study. I will describe the course outline and how the module assignments are handled. Student evaluations of this approach are very favorable, and have also given useful feedback for improving the scheme.
FREE

Loudspeaker requirements for electronic organs in churches (A)

J. Robert Ashley and Roy A. Pritts

J. Acoust. Soc. Am. Volume 66, Issue S1, pp. S31-S31 (1979); (1 page)

Online Publication Date: 11 Aug 2005

Full Text: | Download PDF

Show Abstract
When visiting a strange church, we can identify the organ as a pipe organ or an electronic organ with just a few minutes of listening (and without visual inspection). A run on the pedal organ will show the usual organ loudspeaker to cease radiating below 60 Hz. Modulation distortion will show that the all important middle octave (261–525 Hz) is being radiated from the same cone as the low tones. The lack of high‐frequency power radiation is noticeable. We deem these faults are caused by the fact that organ loudspeakers have not been designed, they have just happened. Dr. J. E. Bensen reported (in 1959) an experiment in the Sydney (Australia) Town Hall which proves this need not be true. We have repeated Dr. Bensen's experiment in the First Methodist Church, Colorado Springs, Colorado, and verified his conclusion. To prove that the recent loudspeaker revolution can make the electronic organ viable, we use a Moog Synthesizer to simulate several pedal and great organ stops.
Return to All Sections
Close

Home Publications Meetings Contact ASA Site Map Back to Top

Copyright © Acoustical Society of America

close