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The Reflections series takes a look back on historical articles from The Journal of the Acoustical Society of America that have had a significant impact on the science and practice of acoustics.

A substantial fraction of the membership of the Acoustical Society of America are faculty at various types of educational institutions and are actively engaged in educational activities. However, papers focusing on aspects of teaching, pedagogy, demonstrations, student learning, and other education topics are not often published in JASA, even though the Education in Acoustics Committee regularly offers special sessions on these topics at every ASA meeting. This special issue of JASA dedicated to Education in Acoustics includes 41 papers from authors all over the world. This introduction to the special issue briefly describes each of the papers, which have been organized into several broad categories: teaching methods and exercises; project-based learning; use of experiments, demos, and experiential learning; adapting to teaching during COVID-19; circuit models and impedance concepts; software apps and online resources; teaching musical acoustics; and descriptions of acoustics programs at a variety of institutions. [ABSTRACT FROM AUTHOR]

In many paper handling machines, the sound radiated from impacts on paper is a major noise source. It is shown that in typical impact line printers both nonresonant and resonant paper vibration are significant mechanisms of sound generation. Both can probably be controlled by increasing the backing bar stiffness of the printer while keeping the printing force constant. The paper-hammer impact on the backing bar dominates paper impact noise below 1250 Hz. Above 2500 Hz the hammer impact on the paper is the dominant source. From 1250-2500 Hz the two impacts contribute equally to the sound generation. Finally, consideration of the design of a ''quiet'' paper leads to the suggestion of a paper with high density and low bending rigidity. This might be accomplished through microcreping of the paper. [ABSTRACT FROM AUTHOR]

Prescoring based upon the material contained in abstracts was used to allocate presentation times for the papers in Speech Communication submitted for presentation at the 80th Meeting of the Acoustical Society. After the papers were actually presented, their technical content, presentation quality, and discussion quality were judged. No casual relationships could be established between the prescoring and postjudging of the paper, although the papers allocated 15 min were judged statistically better in technical content than the papers allocated 5 or 10 min. It is hoped that this letter might entice others to conduct further experimentation and subjective assessment of different methods for improving professional meetings. [ABSTRACT FROM AUTHOR]

Sonoluminescence is the production of electromagnetic radiation, much of it in the form of visible light, that is emitted from a gas-filled cavity that has grown and collapsed under the influence of a varying pressure field. This resource paper provides a guide to the literature of sonoluminescence, from its early history to the present.

Experiments with laser generation and detection of ultrasound in copy paper indicate that earliest arrivals of ultrasound are antisymmetric. A likely explanation is that the out-of-plane interferometer is relatively insensitive to the symmetric compressional pulse because of the low Poisson ratio of copy paper, but rather sensitive to its antisymmetric flexural wake associated with the random heterogeneities and gradients present in copy paper. © 1997 Acoustical Society of America. [ABSTRACT FROM AUTHOR]

A through-transmission, dry-contact ultrasonic technique aimed at investigating sound propagation in the thickness direction of paper materials is presented. The method uses piezoelectric ceramic transducers immersed in fluid-filled rubber wheels. Thickness and longitudinal velocity are determined from time domain measurements for several commercial paper specimens between 40 and 1750 μm. Dispersion and attenuation are reported at frequencies up to 1.5 MHz. Dispersion is less than 10% between 0.25 and 1.25 MHz. Amplitude calculations are used to evaluate the attenuation coefficient versus the frequency. Using a nearly local form of the Kramers-Kronig relationships, the attenuation coefficient is also obtained from the phase information. By comparing the amplitude- and phase-determined attenuation coefficients, an apparent reflection coefficient is predicted. It is shown that the Kramers-Kronig relationships can be applied to papers thicker than 200 μm under dry coupling conditions. The attenuation coefficient is inversely related to the elastic stiffness for homogeneous specimens. A linear relationship is observed between the attenuation loss and the thickness. The apparent reflection coefficient correlates to the apparent surface roughness of paper. [ABSTRACT FROM AUTHOR]

The A0 Lamb mode in copy paper is generated and detected by using laser ultrasonics. The frequency dependence of the group velocity of the A0 mode is found from the wavelet transform of the measured signal. A best fit of the dispersion curve against predictions based on orthotropic plate theory yields an estimate of the bending stiffness of the sample. The sample is enclosed in an environmental chamber so that the effects of temperature and humidity can be controlled. Results indicate that the bending stiffness decreases with increasing temperature at an approximate rate of 4×10-6 N m/°C, and that it decreases with increasing percent moisture content (PMC) at an approximate rate of 2×10-5 (N m)/PMC. © 2002 Acoustical Society of America. [ABSTRACT FROM AUTHOR]

The notebooks of Wallace Clement Sabine were discovered in 1975, and his consulting files were discovered in 1979. Both findings were reported [J. Acoust. Soc. Am. 61, 629-639 (1977); J. Acoust. Soc. Am. 69, 1-7 (1981)]. By chance, his personal papers were discovered recently and highlights from them are presented here with emphasis on his European activities from 1906 to 1917.

Echolocation (i.e., perceiving objects using acoustic echoes) is well-known in underwater detection and to a lesser extent in robot guidance and machine perception. The paper by Tsakiris and McKerrow is concerned with machine perception in air using Freedman's asymptotic model, which was originally developed to predict the backscattering multiple-echo effect observed in sonar detection. This effect was subsequently shown to be due to the elastic response of underwater targets. Freedman's model can be used in air because the acoustic target is assumed to be rigid. Also, the model's prediction of multiple echoes can be used to obtain information about the shape of the target. This is the so-called inversion of the Freedman model by Tsakiris and McKerrow. In their paper, various simple bodies are tested in air using ultrasound and it is shown that the model provides relatively poor information about body shape. Several explanations are given. However, one explanation is not considered, namely that the model itself is not satisfactory. First, there is poor agreement with exact backscattering theory. Second, deriving information about target shape from the multiple echoes predicted by the model is a highly questionable procedure. Both these aspects are examined here.

It has been previously determined that precompressed onionskin paper may be used as an acoustic decoupler. In our evaluation, compressional-wave measurements were made on various types of paper, and in particular onionskin typing paper, at 32 and 1000 kHz. At the lower frequency, a composite material technique was used to allow pressurization of the samples. The velocity of sound and attenuation were found to vary nonlinearly with pressure over the range from 0 to 2000 psi. This nonlinearity introduces a nonlinear acoustic loading of the transducer elements and is the main disadvantage of onionskin paper. However, it was confirmed that the onionskin paper should be more stable with pressure than the other papers, provided that it has been properly precompressed. Most of the insertion loss provided by onionskin paper is caused by the mismatch in acoustic impedance. Thus, a fairly wide variety of materials should provide equivalent acoustical properties. [ABSTRACT FROM AUTHOR]

The papers in this special issue provide a critical look at some historical ideas that have had an influence on research and teaching in the field of speech communication. They also address widely used methodologies or address long-standing methodological challenges in the areas of speech perception and speech production. The goal is to reconsider and evaluate the need for caution or replacement of historical ideas with more modern results and methods. The contributions provide respectful historical context to the classic ideas, as well as new original research or discussion that clarifies the limitations of the original ideas. [ABSTRACT FROM AUTHOR]

In the present editorial, the Editor-in-Chief of the Journal explains the processes by which manuscripts are handled when they are submitted for publication. Various categories of problem papers are described, and it is emphasized that the outcome of the review process is not always predictable. Metrics for measuring paper quality and journal quality are reviewed and discussed. Arguments are given to the effect that the quality of a paper and its chances of being selected for publication will be considerably improved if the authors adopt a philosophy of literate writing and collegial citing. The detailed meaning of these phrases is discussed with accompanying examples, including the case of a paper by J. J. Waterston, the publication of which was delayed for 47 years until the paper was rediscovered by Rayleigh. © 2000 Acoustical Society of America. [ABSTRACT FROM AUTHOR]

The effects of anthropogenic (man-made) underwater sound on aquatic life have become an important environmental issue. One of the focal ways to present and to share knowledge on the topic has been the international conference on The Effects of Noise on Aquatic Life ("Aquatic Noise"). The conferences have brought together people from diverse interests and backgrounds to share information and ideas directed at understanding and solving the challenges of the potential effects of sound on aquatic life. The papers published here and in a related special issue of Proceedings of Meetings on Acoustics present a good overview of the many topics and ideas covered at the meeting. Indeed, the growth in studies on anthropogenic sound since the first meeting in 2007 reflects the increasing use of oceans, lakes, rivers, and other waterways by humans. However, there are still very substantial knowledge gaps about the effects of sound on all aquatic animals, and these gaps lead to there being a substantial need for a better understanding of the sounds produced by various sources and how these sounds may affect animals. [ABSTRACT FROM AUTHOR]

This paper introduces the Special Issue of The Journal of the Acoustical Society of America on Ocean Acoustics in the Changing Arctic. The special issue includes papers on ocean (and in one case atmospheric) acoustics. Changes in both the ice cover and ocean stratification have significant implications for acoustic propagation and ambient sound. The Arctic is not done changing, and papers in this special issue, therefore, represent a snapshot of current acoustic conditions in the Arctic. [ABSTRACT FROM AUTHOR]

The acoustic decoupling behavior of onionskin paper is examined, with emphasis on sonar transducer applications. Nonlinear changes in the sound velocity of onionskin paper with pressure are used to predict the degradation of both frequency and directional response. These results are obtained by computer analysis of a longitudinal-vibrator equivalent circuit. The results are in reasonable agreement with the measured characteristics of a specific transducer configuration. [ABSTRACT FROM AUTHOR]

This paper is a reply to views on aircraft noise in the community and in the passenger cabin of modern jet aircraft presented in three papers at the 86th Meeting of the Acoustical Society in Los Angeles, Nov. 1973 (Papers MM1, MM3, and MM11). It is argued that procedures used by the author of paper MM-1 can result in EPNL values subject to errors of as much as 8 to 15 EPN dB. Recent measurements by Boeing are quoted that are substantially in agreement with those officially determined in 1971 for 727 aircraft on take-off. It is anticipated that landing noise will show similar agreement with published data. Other Boeing measurements using an aircraft in which engine noise was essentially eliminated indicate that it is technologically impossible to achieve the low community noise levels suggested in MM3 at the present time with a viable commerical airplane. Measurements together with widely accepted hearing conservation criteria indicate that travellers are not being exposed to hazardous noise levels inside passenger cabins of modern jets as claimed in paper MM11. [ABSTRACT FROM AUTHOR]

In this paper, a new method of measuring Young's modulus in a paper cone is presented. The characteristics of this method are as follows. (1) The distribution of Young's modulus along generatrix of the cone can be measured. (2) The technology of laser modulation is applied in this method. As a consequence, the setup of measurement has no influence on the vibration behavior. This new method has been tested and verified. © 1996 Acoustical Society of America. [ABSTRACT FROM AUTHOR]

The following group of papers resulted from a special session entitled Speech Recognition and Perception from an Articulatory Point of View that was held during the spring 1994 meeting of the Acoustical Society of America in Cambridge, Massachusetts. Organization of the session began when Richard McGowan, Terry Nearey, and Juergen Schroeter invited speakers to give papers and critiques on the role of articulation in human perception and machine recognition. Presentations were invited from three speakers or groups of speakers who were representative of the three speech areas in the Society: production, perception, and processing. One talk was given by Björn Lindblom, another was given by John Ohala, and the third by Rick Rose, Juergen Schroeter, Mohan Sondhi, and Oded Ghitza. The invited critiquers for the Lindblom paper were Ken Stevens, Robert Remez, and Bishnu Atal; for the Rose et al. paper, Roger Moore, Joe Perkell, and Terry Nearey; and for the Ohala paper, Mary Beckman, Douglas O'Shaughnessy, and Carol Fowler. These people created a very interesting and provocative session. Robert Fox, associate editor of the speech perception section of the Journal, initiated publication of and edited the papers that appear here. Written versions of the invited papers are included here, as well as the critiques by Stevens, Remez, Nearey, Moore, and O'Shaughnessy. Because it was felt that Carol Fowler's view of the importance of articulation in speech perception was not sufficiently aired in a short critique, she was asked to present her views in a longer paper. © 1996 Acoustical Society of America. [ABSTRACT FROM AUTHOR]

This paper suggests an explanation for listeners' greater tolerance to positive than negative mistuning of the higher tone within an octave pair. It hypothesizes a neural circuit tuned to cancel the lower tone that also cancels the higher tone if that tone is in tune. Imperfect cancellation is the cue to mistuning of the octave. The circuit involves two neural pathways, one delayed with respect to the other, that feed a coincidence-sensitive neuron via excitatory and inhibitory synapses. A mismatch between the time constants of these two synapses results in an asymmetry in sensitivity to mismatch. Specifically, if the time constant of the delayed pathway is greater than that of the direct pathway, there is a greater tolerance to positive mistuning than to negative mistuning. The model is directly applicable to the harmonic octave (concurrent tones) but extending it to the melodic octave (successive tones) requires additional assumptions that are discussed. The paper reviews evidence from auditory psychophysics and physiology in favor—or against—this explanation. [ABSTRACT FROM AUTHOR]

This paper describes ongoing developments to an advanced laboratory course at Kettering University, which is targeted to students in engineering and engineering physics and emphasizes theoretical, computational, and experimental components in the context of airborne acoustics and modal testing [cf. D. A. Russell and D. O. Ludwigsen, J. Acoust. Soc. Am. 131, 2515–2524 (2012)]. These developments have included a transition to electronic laboratory notebooks and cloud-based computing resources, incorporation of updated hardware and software, and creation and testing of a multiple-choice assessment instrument for the course. When Kettering University suddenly shifted to exclusively remote teaching in March 2020 due to the COVID-19 pandemic, many of these changes proved to be essential for enabling rapid adaptation to a situation in which a laboratory was not available for the course. Laboratory activities were rewritten by crowdsourcing archived data, videos were incorporated to illustrate dynamic phenomena, and computer simulations were used to retain student interactivity. The comparison of multiple measures, including the assessment instrument, team-based grades on project papers, and individual grades on final exams, indicates that most students were successful at learning the course material and adapting to work on team-based projects in the midst of challenging remote learning conditions. [ABSTRACT FROM AUTHOR]

The article offers information on the patent application 7,445,173 related to a device for reducing vibration as well as noise of a paper shredder assigned to Michilin Prosperity Co. Ltd. In order to reduce vibration and noise, a paper shredder core assembly is attached to a housing base using buffer devices. The paper shredder core assembly is composed of frames, cutting assembly, gear set and motor.

The recent paper by Hueter et al. on ultrasonic lesions in the central nervous system, which appeared in a recent issue of this Journal (March, 1956), presents a rather limited view of this field and may lead to some misunderstandings. This note is a critical analysis of the Hueter paper. Some of the more important points discussed are: (1) The unique advantages of producing ultrasonic lesions in the brain by using dosages appropriate for selective action combined with focusing of the beam in contrast to the use of focusing alone. (2) The choice of an irradiation procedure in experiments designed for the elucidation of physical mechanisms of the action of ultrasound on tissue. (3) The specification of the acoustic variables required for a dosage description. (4) The inapplicability of Eyring's theory of viscosity, plasticity, and diffusion to the elucidation of observed dosage relations. (5) The clarification of the usage of the terminology, nontemperature effects. (6) The applicability of the reciprocity method for the calibration of thermo-couple probes. [ABSTRACT FROM AUTHOR]

The COVID-19 pandemic has been a global event affecting all aspects of human life and society, including acoustic aspects. In this Special Issue on COVID-19 and acoustics, we present 48 papers discussing the acoustical impacts of the pandemic and how we deal with it. The papers are divided into seven categories which include: physical masking and speech production, speech perception, noise, the underwater soundscape, the urban soundscape, pathogen transmissibility, and medical diagnosis. [ABSTRACT FROM AUTHOR]

Critiques by A. Cohen, H. Davis, B. L. Lempert, and W. D. Ward of my paper 'Impairment to Hearing from Exposure to Noise' are treated individually. Questions raised by the reviewers are discussed and areas for further discussion are noted. [ABSTRACT FROM AUTHOR]

There are currently no models to fully predict the effects of internal wave induced scattering on acoustic pulses. Existing models, which predict time domain statistics, either use the ray-based path integral method or Monte Carlo type simulations. The path integral method fails to accurately predict all of the effects of scattering. The Monte Carlo methods base the statistics on ensemble averages and are not physics-based models. This paper overcomes these limitations by using the modes of the waveguide in a transport theory application. The transport theory equations have, thus far, been used only to explain diffusion of mode intensities and decorrelation due to internal waves at individual frequencies. This paper extends the current narrowband application predict mode correlations across different frequencies and, from that, the broadband time-front, time wander, travel time bias, and the amount of spread in intensity across time and depth. To validate these predictions, this paper uses separate parabolic equation simulations. The comparisons between the two are good, suggesting a success for the mode-based transport theory approach. [ABSTRACT FROM AUTHOR]

In this paper, we consider the problem of bearing ambiguity in the direction of arrival (DOA) estimation due to spatial aliasing when the minimum wavelength of the processing broadband signal is less than the element spacing of a uniform linear array (ULA). First, an extended frequency-difference (FD) method is presented. Unlike the existing FD methods, the extended FD signal is constructed by conjugate multiplying a diagonal matrix consisting of steering vectors at high frequency and pre-processing direction with the array sampled signal matrix at low frequency. Then, this paper establishes a decision criterion for distinguishing the aliasing component that varies linearly with frequency in the extended FD space. Finally, an unambiguous broadband DOA estimation method is achieved by suppressing spatial aliasing in the extended FD space. The simulation results show the effectiveness of the proposed method in low signal-to-noise ratio, low signal-to-interference ratio, and multi-interference conditions. The unambiguous processing ability of the proposed method is further verified in the South China Sea using ship signals in the frequency band of 200 to 700 Hz and a 10-element ULA with a 6.25 m spacing deployed on the seabed. [ABSTRACT FROM AUTHOR]

In the original paper [Yasui and Izu, J. Acoust. Soc. Am. 141(6), 4398–4407 (2017)], the temperature gradient in Rott equations was assumed as zero by mistake as an author error, although temperature gradient was adequately taken into account in the numerical simulations of thermal conduction between a fluid parcel and the wall of a stack. In the present erratum, the results of the corrected numerical simulations are shown. The results show that the pV work done by a fluid parcel is larger in a wet stack compared to that in a dry stack not only in a traveling-wave thermoacoustic engine but also in a standing-wave thermoacoustic engine. The pV work is determined not only by the volume oscillation amplitude of a fluid parcel but also by the change in the mean volume of a fluid parcel. [ABSTRACT FROM AUTHOR]