Index of content:
Volume 27, Issue 5, September 1955
- PROGRAM OF THE FORTY‐NINTH MEETING OF THE ACOUSTICAL SOCIETY OF AMERICA
- Session A. Music and Speech
- Contributed Papers
27(1955); http://dx.doi.org/10.1121/1.1917947View Description Hide Description
The acoustic spectra of a cornet have been measured with the instrument equipped with several mutes of the type used in dance orchestra work. Data will be presented showing the sound pressure levels of the first ten to fifteen overtones of the instrument when fitted with each of the mutes. The instrument was blown naturally by a cornetist, with an attempt to obtain a normal characteristic tone for each mute. The sound spectrum of the muted instrument will be compared to that of the open or unmuted instrument. The mutes tend to exhibit the same formant or frequency response for several different notes, indicating resonance phenomena in the acoustic networks. The measurements have been made by playing the instrument in a dead room and recording the sound on tape with a high quality condenser microphone and magnetic tape recorder. The sounds were then analyzed by playback through a heterodyne type wave analyzer.
27(1955); http://dx.doi.org/10.1121/1.1917948View Description Hide Description
Radiographs and photographs of trumpet players were made while the tones they produced were recorded. Detailed measurements were made of the anatomical positions assumed by each player for each tone and for spoken vowels. The vowel orientations used in producing tones in three different octaves were compared with the formant patterns evidenced in the trumpet tones. A close relationship was found to exist. The report of the results of the study will include slides depicting radiographs of the oral and pharyngeal cavities and graphic representations of the acoustical structure of the tones produced.
27(1955); http://dx.doi.org/10.1121/1.1917949View Description Hide Description
The aim of the paper is to resolve a conflict between observations. In the observations, the stimulus is a complex, periodic wave consisting only of high‐frequency harmonics of a “missing” fundamental. Schouten found that a low subjective pitch was heard even when a search tone revealed no fundamental. And, recently, low pitch has been heard despite the presence of strong low‐frequency masking noise. Yet, using five independently generated harmonics, Hoogland found that the low pitch emerged only when the sound intensity was high and nonlinear distortion produced an audible fundamental. The conflict is resolved by taking into account the phase pattern of the harmonics, which Hoogland did not control. When one adjusts the phases haphazardly, he often duplicates Hoogland's finding. But, when he adjusts them in such a way that all the harmonics come into their maxima at the same time and in sum produce an impulsive wave form, Schouten's low‐pitched “residue” is clearly heard. Hoogland's observations thus fall neatly into line with composite place‐periodicity theory.
27(1955); http://dx.doi.org/10.1121/1.1917950View Description Hide Description
Equipment was assembled and a procedure was developed for the measurement of power spectra of consonants. Detailed power spectra as well as measurements of grosser spectral properties were made on a fairly large sample of English and Russian stops and fricatives. Special criteria were developed for the evaluation of the data obtained. Possibilities of utilizing the data automatic recognition were considered.
27(1955); http://dx.doi.org/10.1121/1.1917951View Description Hide Description
This paper reports on the frequency analysis of speech. Various distortions of speech sounds, such as “differentiation,” “integration,” and “peak clipping,” have been studied in terms of both wave form and spectrum. The results can be related to articulation scores obtained for speech communication systems by previous investigators. Comparisons have also been made with published data on the spectrum levels of speech. The effects of time constants on these results will be discussed.
- Session B. Sound in Fluids
27(1955); http://dx.doi.org/10.1121/1.1917952View Description Hide Description
In 1950, Gierer and Wirtz advanced a theory of ultrasonicabsorption in liquids that attributed virtually all excess absorption to processes involving dislocation migrations in quasi‐crystalline liquids. In particular they deduced an expression for the temperature dependence of α involving only one acoustically determined parameter. Use has been made of this theory to calculate the mean temperature coefficient of the absorption coefficient for a number of liquids for which the appropriate physical data were available. In all cases, the agreement with the experimentally determined temperature dependence is very poor, and in general the correct sign for the coefficient is not predicted by the theory. Since the theory was supposed to account for absorption in both associated liquids (negative temperature coefficient) and nonassociated liquids (positive temperature coefficient), the results suggest that the proposed theory is not acceptable. This work was supported in part by the Office of Naval Research.
27(1955); http://dx.doi.org/10.1121/1.1917953View Description Hide Description
Measurements of ultrasonicabsorption have been made in an associated and a nonassociated liquid as a function of hydrostaticpressure in order to compare the pressure dependence of the relaxation phenomena involved. Absorption data were obtained in carbon bisulfide (non‐associated) at frequencies from 15 to 65 mc, up to pressures of 1000 kg/cm2 and at a temperature of −29°C. At this temperature and at atmospheric pressure the data could be fitted by assuming a relaxation frequency of 44.6 mc. As the pressure was raised the absorption coefficient decreased and the relaxation frequency increased. At 1000 kg/cm2 the relaxation frequency was over 65 mc. Absorption measurements in glycerol at 0°C over the same frequency and pressure range showed that the relaxation frequency decreased from about 55 to 43 mc as the pressure is raised. These results are in accord with the concept that different mechanisms of excess sound absorption exist in these two liquids.
27(1955); http://dx.doi.org/10.1121/1.1917954View Description Hide Description
It is desirable to have more experimental data concerning the acoustical properties of liquids not only because such data will lead to a better understanding of the liquid state but also because of the immediate application of such results to the development of acoustical devices. Acoustical velocities were measured at 500 kc in a number of organic liquids and binary solutions prepared therefrom. A precision ultrasonic interferometer was employed. For the most part sound velocities were found to vary linearly with temperature. Densities were determined at 20°C. Adiabatic compressibilities at 20°C were calculated and some conclusions drawn concerning the cohesive properties of certain of the solutions. The molecular sound velocity in a binary liquid solution is the sum of the products of the respective molecular sound velocities in the pure liquids by their corresponding mole fractions all at the same temperature. Where practicable, effective molecular radii were calculated from the data. The usefulness of the molecular weight of the liquid in predicting values of the temperature coefficient of velocity is discussed. Apparently many more experimental data are needed before an adequate theoretical analysis is possible.
27(1955); http://dx.doi.org/10.1121/1.1917955View Description Hide Description
The absorption of sound in aqueous solutions was studied over the frequency range 1–55 Mc as a function of concentration, temperature, dielectric constant, and with as solvent. The absorption maximum in the range 1–10 Mc was verified, and also a secondary relaxation peak, not previously reported, was observed near 30 Mc. The primary relaxation frequency was decreased when the dielectric constant was lowered, while the secondary relaxation frequency was increased. The absorption cross section was increased when the dielectric constant was decreased. The activation energy was determined for both isodielectric and isocomposition solutions. Substitution of as a solvent had no effect on the primary relaxation frequency but increased the absorption cross section. The secondary relaxation was not observed in solutions. The results indicate that a reaction between two ions of unlike sign is not the rate‐determining step in the primary relaxation process and that a reaction between ions of like sign is also improbable. All observed data can be explained on the assumption that the reaction is between two dipole molecules. This work was sponsored by the Office of Ordnance Research.
27(1955); http://dx.doi.org/10.1121/1.1917956View Description Hide Description
The attenuation of 10 megacycle sound pulses in the liquid crystalpara‐azoxyanisole is presented as a function of temperature in the region of the liquid crystal—isotropic liquidphase change. An absorption peak of optical sharpness is encountered at a temperature Tc just above the phase transition temperature. As one might suspect, Tc is dependent upon external influences. The dependence on externally applied magnetic fields is presented and the significance of these measurements is discussed. This work was supported in part by the Office of Naval Research.
27(1955); http://dx.doi.org/10.1121/1.1917957View Description Hide Description
The ordinary single‐crystal interferometer has been used by many investigators for attenuationmeasurements in liquids. The accuracy is poor because the peaks and dips have a complicated dependence on attenuation,reflection coefficient at the reflector, and parallelism of crystal and reflector. It will be shown that if the crystal is connected to an appropriate circuit, the voltage on the crystal will have a complex exponential dependence on the crystal‐to‐reflector distance. That is, the amplitude will fall off exponentially, and the phase will shift linearly, with path length; the reflection coefficient does not affect the results. The advantages of this arrangement are (a) the attenuation is measured directly, and (b) good velocity measurements can be made on liquids even if the attenuation is so high that the dips that are gotten with the conventional arrangement are few and poorly defined.
27(1955); http://dx.doi.org/10.1121/1.1917958View Description Hide Description
Measurements were made to compare the relative effectiveness of and molecules in influencing thermal relaxation in gas. Thermal relaxation times were obtained from absorption measurements taken in and mixtures. The “direct” absorption technique was employed in conjunction with pulsed sound waves having a carrier frequency of 110 kc. Data were taken in the region of 100–700 kc/atmos and at a temperature of 21°C. Commercial anhydrous was used in this research. In dried a value of 0.153 was obtained for the maximum amplitude absorption coefficient per wavelength. Measurements were taken at vapor concentrations of 0.39%, 0.77%, and 1.14%; an average value of 1.70 was obtained for the relative collision transition efficiencies of and . This value is comparable to the figure of 1.86 obtained by D. Sette and J. C. Hubbard [J. Acoust. Soc. Am. 25, 994 (1953)] for and . This work was supported by the Office of Naval Research.
- Session C. Bioacoustics
- Invited Papers
27(1955); http://dx.doi.org/10.1121/1.1917959View Description Hide Description
The ultrasonic focused beam method of producing selective, precisely localized, quantitatively reproducible lesions in the brains of experimental animals is illustrated. The acoustic calibration procedure, the surgical preparation of the animal, and the technique of irradiation are demonstrated in this motion picture. The complete instrumentation setup is shown in operation. A lesion is produced in the depths of the brain of a monkey. This technique, which is currently being used in studies of brain structure and function, was developed at the Bioacoustics Laboratory of the University of Illinois. A lesion of practically any desired size (as small as one millimeter in diameter) and shape can be produced at any specified location in the brain without disturbance of intervening tissue and without disruption of blood vessels even within the site of the lesion. In addition, it is possible by proper choice of the dosage to irreversibly affect fiber tracts (white matte) without destroying surrounding or neighboring nerve cell bodies (gray matte)r which receive the same dosage of radiation. This means that in producing lesions in white matter it is readily possible to retain the boundary between white matter and neighboring gray matter as the boundary of a lesion produced by ultrasound. Examples of ultrasonically produced lesions in both white and gray matter of a variety of sizes and shapes and at various depths in the brain will be illustrated by stained tissue sections. This procedure represents a significant advance over other methods of producing lesions which have been used up to the present time. The method has considerable potential value for neurosurgery.The support, in this research field, of the Physiology Branch of the Office of Naval Research is acknowledged.
27(1955); http://dx.doi.org/10.1121/1.1917960View Description Hide Description
The dissipation of vibrational energy in tissues may be ascribed to one or more of the following four loss mechanisms: (a) viscous damping; (b) structural rearrangement; (c) elastic hysteresis; (d) scattering. Each of these mechanisms exhibits a characteristic dependence of attenuation on frequency. Losses of type (a) and (b) are accompanied by velocity dispersion and losses of type (c) inherently lead to a dependence of attenuation on the amplitude of vibration. The available evidence indicates that below 20 kcps viscosity is the controlling factor. In the frequency range from 200 kcps to 10 mcps a constant loss per cycle is often observed which may be interpreted either in terms of a distribution of relaxation times or as a hysteresis due to the plasticity of tissues. In tissues of marked inhomogeneity or at interfaces between structures of different acoustic impedance, scattering produces additional attenuation. The relative roles and magnitudes of these loss mechanisms are of direct interest in medical applications of ultrasound such as physio‐therapy, brain surgery, and diagnosis of abnormal growth. More general ultrasonic absorption studies are valuable for the understanding of the physics of living tissues.
27(1955); http://dx.doi.org/10.1121/1.1917961View Description Hide Description
The behavior of the human body in receiving and transmitting vibrations is reviewed. Measurements in this area were made for two purposes: (1) to determine the pathways to the body surfaces taken by vibrational energy generated inside the body by such excitations as human speech and muscular activity of the heart, and (2) to determine the vibrations inside the body as a result of exposing the body surface to vibrations, e.g., the physical aspects of hearing (which will not be discussed in this review), cases where parts of the body surface are brought into contact with vibrating machinery or where the whole body is exposed to a sound field. The impedances measured on different areas of the body surface and their practical application to physiological, mechanical, and engineering purposes are discussed. Examples are given of how the body impedances influence the design of ballistocardiographic tables and of ear protectors and how knowledge of these impedances determines the usefulness of vibration pickups attached to the body surface. Vibration characteristics of certain parts of the body such as the skull, losvet jaw, and chest are briefly summarized. The present status of the problem of absorption of airborne sound by the body surface is reviewed and some of the unsolved questions discussed.
- Contributed Papers
27(1955); http://dx.doi.org/10.1121/1.1917962View Description Hide Description
Local and systemic changes were studied in hairless mice following irradiation of the integument with high intensity airborne sound. Comparisons were made between effects of subthermogenic (without skin heating) and thermogenic (skin heating) sound levels. Criteria, other than morphological, used in skin analyses included cytochemical examination of skinlipids, glycogen, PAS‐reactive substances, and alkaline phosphatase. Failure to induce injury or any change in skin cytochemistry after local skin irradiation daily for three months with subthermogenic sound (18 kc, 150 db) indicated that direct effects of sound are negligible at these levels. The inflammatory response of skins exposed to higher sound levels (20 kc, 160–168 db) was found to result from local absorption of sound energy and its conversion into heat. Analysis of systemic effects included studies of changes in adrenal, hemopoietic, and reproductive organs.Skin treatment with subthermogenic sound produced no appreciable systemic response. A marked systemic reaction, however, always accompanied sound induced skin burns. Additional studies on effects of auditory stimulation on adrenals and eosinophils showed that prolonged exposure of mice to loud noise fields (10–20 kc, 110 db) proved to elicit only a mild systemic response. This work was sponsored in part by the Aero Medical Laboratory, Wright‐Patterson Air Force Base, Dayton, Ohio, under contract No. AF 33(616)‐2505
27(1955); http://dx.doi.org/10.1121/1.1917963View Description Hide Description
The measurements reported here were carried out to check those calculated from the heating of mice in the field of the Penn State siren [Danner, Ackerman, and Frings, J. Acoust. Soc. Am. 26, 731–39 (1954)]. In the present experiments the mice were placed in individual containers in a white noise field within a cylindrical reverberant chamber. Reverberation times were measured using filtered portions of the output of a 633 A microphone placed within the chamber. Care was taken to assure that the absorption coefficientsmeasured were not a function of the number of mice in the chamber. In agreement with the siren measurements these reverberation time measurements showed an increase of the acoustic absorption with increasing frequency for both haired and hairless mice; the numerical values of the absorption coefficient from close to 100% for haired mice at 20 kc down to less than 10% for hairless mice at 6 kc showed agreement within the limits of experimental error. This work was supported in part by USAF contract No. 33(038)‐786.
- Session D. Speech
27(1955); http://dx.doi.org/10.1121/1.1917964View Description Hide Description
An auditory test to establish the adequacy of an idealized specification of vowel articulation is described. Articulatory configurations of the vocal tract are specified by means of three numbers: the position of the point of greatest constriction, the degree of constriction at that point, and the size of the mouth opening. The stimuli in the recorded test are the outputs of 279 such configurations of an electrical vocal tract analog. All sound samples are highly similar in duration, intensity, start‐stop characteristics, and fundamental frequency and inflection. The instructions to subjects are standardized, and are of two types: one restricts responses to one of nine vowel categories while the other permits a nonvowel response as well. Subjects were experienced in phonetic transcription. The ranges of articulatory configurations identified as given vowels by the subjects are plotted as contours, and these data are compared to results of other investigators. Certain disagreements are pointed out and discussed. The results, in general, show good agreement with previous data, and demonstrate, therefore, the adequacy of the three‐number articulatory description. This work was supported by funds from the Air Force Cambridge Research Center.
27(1955); http://dx.doi.org/10.1121/1.1917965View Description Hide Description
Listener reception of intelligibility test materials was studied as a function of the amount of prior exposure to the speaker's voice. Separate evaluations were made for listening in quiet and listening in noise. The procedure for each evaluation involved one group of listeners receiving no exposure to the speakers' voices, a second group receiving two‐minute exposure, a third group receiving four‐minute exposure, and a fourth group receiving eight‐minute exposure to the recorded voices of each of the four speakers who read intelligibility test words. Mean reception values for lisening in quiet were significantly higher for the listening groups exposed to the speakers' voices two, four, or eight minutes than was the mean reception value for the listening group which was not exposed to the speakers' voices. For listening in noise, the mean reception value was significantly higher only for the listening group exposed to the speakers' voices for eight minutes as compared to the mean reception values for the listening groups who were not exposed to the speakers' voices or who were exposed to the speakers' voices for two or four minutes. Mean values of listener reception did not follow the same trend for each speaker.
27(1955); http://dx.doi.org/10.1121/1.1917966View Description Hide Description
Generally quality defects of voice are presented as “independent of phonemes,” i.e., the sounds being articulated, and as the result of the unique wave composition of voice defective speakers. The purpose of this study was to investigate a voice quality disorder while varying specific speech sounds. The subjects with hoarse voice quality were selected to speak syllables in which the phonetic elements were controlled. The utterances were recorded and played to trained judges who rated the degree of hoarseness present in the utterance. Statistical analysis(analysis of variance) of the data collected indicated that significant differences in voice quality do exist as some function of the vowel and consonant content of the syllable. Further analysis (t test) reveals that high vowels result in significantly less judged voice quality defectiveness than the low vowels. Front‐back vowel comparisons were generally less indicative of real differences. Of the consonants, it is seen that the voiceless, or whispered, plosives, such as t, p, and k, contribute to a judgment of less defectiveness than the other consonants. Generally, the findings are that voiceless consonants are judged less defective than voiced consonants, fricatives increase the judgment of hoarseness, the manner of articulation of consonants is related to perceived voice quality and place of articulation appears to have only slight correlation. In general the results suggest that the degree of perceived voice quality may be related in part to the secondary acoustic characteristics of syllables, such as duration, frequency, and intensity. Such investigations are now in progress.