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Nov 1981

Volume 70, Issue S1, pp. S1-S109

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back to top Session K. Musical Acoustics I: General
Contributed Papers
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Using nearfield holography to study energy flow from musical instruments (A)

W. Y. Strong, Jr., T. B. Beyer, D. J. Bowen, E. G. Williams, and J. D. Maynard

J. Acoust. Soc. Am. Volume 70, Issue S1, pp. S22-S22 (1981); (1 page)

Online Publication Date: 12 Aug 2005

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We have developed a technique called nonwavelength limited, or nearfield, acoustical holography that can experimentally determine the radiated pressure field, particle velocity field, and the vector intensity field of low‐frequency (below 1500 Hz) sound sources where the source is often smaller than a wavelength. Mappings which show the rate and direction of the acoustic energy flow from the source (nearfield) out to the farfield may be constructed. These mappings are valuable for locating sound sources and determining their strengths. Most of our early work focused on relatively simple sources, but recently we have been looking at more complex sources such as musical instruments, specifically guitars and cellos. The instruments are intact and string excited. Holographic reconstructions of the top of the guitar show both the plate motion and the motion of the air in the rose. Preliminary results indicate that the rose is a dominant source of the radiated sound energy over the first two octaves of the guitar's range. Maps of the energy flow around and away from the instrument will be presented.
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Brass wind instrument impulse response measurements (A)

A. H. Benade and J. H. Smith

J. Acoust. Soc. Am. Volume 70, Issue S1, pp. S22-S22 (1981); (1 page)

Online Publication Date: 12 Aug 2005

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Apparatus has been built for pulse reflectometry of brass instruments. The current version uses spark excitation and an electret microphone at the mouthpiece rim terminating plane. Selectable low pass filtering in the microphone channel reduces noise and aids in the visual interpretation of reflected pulses via control of signal bandwidth. Discontinuities of air column cross section, taper, etc. can be located and identified using familiar techniques from electrical reflectometry. Multiple‐reflection patterns characteristic of prototype musical shapes must be taken into account. These are being worked out. Reflectogram FFT's give input impedance functions in good agreement with those obtained via swept frequency capillary excitation methods. Studies of several tubas show that availability of both time and frequency domain representations of the response function greatly increases diagnostic power for the evaluation and correction of instruments. Comparisons will be made with reflectometer data of Krüger (Zwota, DDR) and the tuba impedance measurements of Caussé (IRCAM, Paris). [Work supported by NSF.]
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Anomalous behavior of a clarinetlike system (A)

John Backus

J. Acoust. Soc. Am. Volume 70, Issue S1, pp. S23-S23 (1981); (1 page)

Online Publication Date: 12 Aug 2005

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Some preliminary work has been done on the problem of understanding in detail the interaction between the vibrating clarinet reed and its associated vibrating air column. In the course of the work, a configuration of brass tubing with tone holes was found which is rather difficult to sound with a clarinet mouthpiece and reed and which produces a poor “stuffy” tone. The input impedance curve of the configuration does not appear to be sufficiently different from that of a conventional clarinet to explain this behavior. Measurements with an impedance tube showed that at the amplitudes associated with playing, nonlinear effects at the tone holes produce an increase in the acoustic resistance that lowers the Q of the system by about a factor of two. However, this also does not appear to explain the difficulty of sounding the configuration; it was found that the Q of a piece of tubing could be lowered by about a factor of two by lining the wall with an insert of emery cloth, yet the rough wall tube could be sounded about as easily as a smooth tube. It is hoped that understanding this configuration will help in understanding the behavior of the clarinet, so work is continuing. [Work supported by the National Science Foundation.]
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Oboe and bassoon perturbation weight function measurements (A)

A. H. Benade and J. C. Carman

J. Acoust. Soc. Am. Volume 70, Issue S1, pp. S23-S23 (1981); (1 page)

Online Publication Date: 12 Aug 2005

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The adjustment of woodwind air columns for proper tuning and intermode cooperation requires knowledge of the fractional mode frequency shifts (Δf/f)n produced by air column cross‐section perturbations Sp(x), as represented by the formula (Δf/f)n  =  − ∫ 0LWnSpdx. In the conical woodwinds direct measurement of the weight function Wn(x) via a movable perturbing volume is not practicable. Instead, closely spaced probe microphone measurements of the modal pressure wavefunctions permit calculation via
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. We have measured the set of Wn′s of several representative fingerings on the Triebert system 6A (conservatory), system 3, and Vienna Academy system oboes, and on the German system bassoon. Effects of nonuniform taper, tone holes, etc. are in agreement with theoretical expectation. Overall the patterns of inter‐instrument similarity and of departure from simple‐cone behavior are quite parallel to what we reported earlier for the clarinet family. [Work supported by NSF.]
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Measurements of violin vibrato (A)

Joan E. Miller

J. Acoust. Soc. Am. Volume 70, Issue S1, pp. S23-S23 (1981); (1 page)

Online Publication Date: 12 Aug 2005

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The periodicity of bowed violin strings has been measured with high resolution by means of a specially designed violin bridge and computer interface. (See ASA Meeting, May 1981, Ottawa, Canada.) The equipment has been used here to examine various characteristics of vibrato. Period lengths are measured with accuracies ranging from 0.5 to 4 cents for a corresponding frequency range of 195 to 1950 Hz, and the four strings are each sampled every 5 ms. Thus, data are gathered in the form of a time series whose probability density and spectrum can be estimated. These measures are examined in the context of actual music as well as sustained notes played on different strings with different fingers and in different positions by different players.
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Coupling of violin string vibrations to the acoustic field (A)

Gabriel Weinreich and Eric B. Arnold

J. Acoust. Soc. Am. Volume 70, Issue S1, pp. S23-S23 (1981); (1 page)

Online Publication Date: 12 Aug 2005

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We have developed a method for determining the monopole and dipole moments of a violin resulting from unit force amplitude applied at the string, at any frequency corresponding to a string resonance, that is, at a frequency at which the instrument would be bowed. What is actually measured is the quantity related to this by a reciprocity theorem, namely, the amplitude of string displacement produced by a controlled acoustic pressure and pressure gradient. The violin is immersed in turn in acoustic fields produced by each of four independent speakers and the string displacements (for both string polarizations) are measured; in each of the four cases, we also determine the acoustic pressure and the three components of pressure gradient at the position of the violin. By a computer superposition, fields that have unit pressure amplitude and zero gradient, and fields that have unit gradient component in each direction but zero pressure, are simulated. From this the moments can be calculated. Results on a number of violins will be reported. [Work supported by NSF.]
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Recent plate mode findings compared with tests on the free plates of Stradivarius violin (A)

Carleen M. Hutchins

J. Acoust. Soc. Am. Volume 70, Issue S1, pp. S23-S23 (1981); (1 page)

Online Publication Date: 12 Aug 2005

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Recent findings indicate that in the best violins we have been able to make so far eigenmodes 1, 2, and 5 in the unattached top violin plate lie in a harmonic series with mode 5 around 370 Hz and modes 2 and 5 in the back at matching frequencies. An early test on the disassembled plates of a fine concert Stradivarius violin corroborates these findings.
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A study of the pitches produced by violinists while playing a short piece of music (A)

M. V. Mathews and J. E. Miller

J. Acoust. Soc. Am. Volume 70, Issue S1, pp. S23-S23 (1981); (1 page)

Online Publication Date: 12 Aug 2005

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Computer recordings were made of the pitches produced by four violinists playing a section of a Mozart (G Major) violin‐piano sonata and a G Major scale. Twelve repetitions of the scale and sonata were recorded. The sonata was played with a recorded piano accompaniment. Selected notes in the recorded material were analyzed to study the variation in pitch from repetition‐to‐repetition of the same note, variation in pitch in different parts of the note, and to observe the pitch variations produced by vibrato. The pitch transitions between successive notes were also observed.
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Nonlinear vibrations in plates and gongs (A)

Thomas D. Rossing and N. H. Fletcher

J. Acoust. Soc. Am. Volume 70, Issue S1, pp. S23-S24 (1981); (2 pages)

Online Publication Date: 12 Aug 2005

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Certain types of gongs show a frequency shift, up or down, when struck. In order to understand this nonlinear behavior, we have studied a variety of flat and curved plates under varying amounts of radial tension or compression. Flat plates show a nonlinearity of a hardening type, whereas most curved plates show softening behavior. The degree of nonlinearity appears to be sufficient to explain the frequency shift observed in Chinese opera gongs [T. D. Rossing and R. E. Ross, J. Acoust. Soc. Am. Suppl. 1 64, S150 (1978)]. [Work supported by the U.S.‐Australia Cooperative Science Program and by the Australian Research Grants Committee.]
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Spectral and perceptual analysis of percussion instruments (A)

Elizabeth Cohen, Michael S. Hart, and Andrew Schloss

J. Acoust. Soc. Am. Volume 70, Issue S1, pp. S24-S24 (1981); (1 page)

Online Publication Date: 12 Aug 2005

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A series of recordings of percussion family instruments were made in both live and anechoic settings. We examined the response of idiophones (cymbals, gongs, chimes) and membranophones to strokes gauged to produce approximate levels for pp, p, mp, f, etc., which differ by roughly 10 dB. An assortment of strokes, including rim shots, were also included. The sounds were recorded on a Nagra stereo recorder, digitized and analyzed. The results from the three‐dimensional spectral plots were compared to subjects data as to pitch and spectral content of instruments. From the study of some members of the idiophone family, we are able to detect certain temporal and spectral characteristics pertinent to the evolution of Chinese gongs. The degree of inharmonicity of the partial sequence for these instruments was also measured.
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Piano training system using a micro‐computer and the characteristic extraction of the learners' playing a fundamental etude (A)

Ikuo Kitagaki and Kunihiro Suetake

J. Acoust. Soc. Am. Volume 70, Issue S1, pp. S24-S24 (1981); (1 page)

Online Publication Date: 12 Aug 2005

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A computerized piano training system is discussed here. It consists of a keyboard adaptor quasi‐fixed in a piano, a micro‐computer, and a TV monitor fitted with it. The system permits detecting time when a learner depresses a keyboard, processes the data, and evaluates the playing. The data and the evaluated information are displayed graphically on a TV monitor. Considering that a fundamental etude is essential as an educational material and that physical measure of the playing of an etude is considered to be more significant than that of popular musical compositions, we designed the system focusing on the playing of fundamental etudes such as “Hanon.” With the system, we obtained data on about three hundred learners. Thus, it became clear that the playing of the Hanon Etude can be classified into three kinds of typical patterns.
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Absolute tonality and absolute pitch (A)

W. Dixon Ward and Ernst Terhardt

J. Acoust. Soc. Am. Volume 70, Issue S1, pp. S24-S24 (1981); (1 page)

Online Publication Date: 12 Aug 2005

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The initial 5 s of each of the 12 major‐key preludes from Bach's Well‐Tempered Clavichord was recorded as written and also shifted by ±1, 4, 6, or 7 semitones, and a randomized tape consisting of two repetitions of each of the 108 items was prepared. Twenty musicians, mostly pianists, decided whether each item was played in the correct key, transposed up, or transposed down; a simplified version of the original (correct) score was printed on the answer sheet. Only two subjects failed to discriminate, at the 5% confidence level, the correct rendition from the transposed ones, even when only the ±1‐semitone transpositions are considered. The four subjects claiming to possess absolute pitch performed slightly better than the rest, but it is clear that absolute identification of tonality is an ability that is more widespread than commonly supposed. The results support the “unlearning” theory of Abraham and Watt: an inborn potential for developing absolute pitch is relatively common, but it tends to become atrophied or suppressed because of the far greater importance of relative pitch in our musical environment. [Research supported by the Bryng Bryngelson Communication Disorders Research Fund.]
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More on “lucky” equal temperaments (A)

Donald E. Hall

J. Acoust. Soc. Am. Volume 70, Issue S1, pp. S24-S24 (1981); (1 page)

Online Publication Date: 12 Aug 2005

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Equal temperaments with N tones per octave can only approximate the small‐integer frequency ratios of just tuning. At the Iowa City conference (May 1981) I discussed a probability approach to the question of just how remarkable are the close fits made available by values such as N = 12, 19, 31, and 53. After briefly reviewing that method, I will present an extension of the calculated results up to N = 600, as well as some remarks about ways of predicting which values of N should be “lucky.”
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