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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.

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.

The following group of papers resulted from a special session entitled SpeechRecognitionandPerceptionfromanArticulatoryPointofView 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 Bjo¨rn 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 etal. 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.

Acoustic transmissions from a low‐frequency source near Heard Island in the southern Indian Ocean were monitored at 16 sites worldwide. The results are presented in the following papers. A summary is presented of what has been learned about the dimensions of this new subject: global acoustics.

Deinking remains an important step in environmentally conscious manufacturing of paper. A novel method based on acoustic‐coaxing‐induced microcavitation is presented for deinking of xerographic ink from paper. Microcavitation evolves microimplosions which are effective in deinking. Acoustic coaxing is an acoustic mediation that enables one to control the onset, intensity, and evolution of acoustic microcavitation. Acoustic microcavitation is brought about by low‐megahertz acoustic fields giving rise to micron‐size bubbles that live a few microseconds. Liquid‐borne microparticles when exposed to strong sound fields will not, ordinarily, cause any cavitation. However, if in addition to this sound field there exists even a very weak, high‐frequency auxiliary acoustic field, cavitation by the microparticles is readily facilitated. This technique of facilitating cavitation is referred to as ‘‘acoustic coaxing.’’ Acoustic‐coaxing methods for deinking are a chemical‐free, environmentally responsible means of recycling paper. Here, initial experimental results are presented and the technique is elaborated upon in detail for easy implementation. Preliminary results indicate that the paper fibers are entirely undamaged, and the ink separation leaves them immaculately white. The microimplosions appear to occur preferentially at the ink sites.

At present, the paper industry lacks an on‐line, noncontact quality control system. Several studies indicate that there are strong correlations between paper strength and elastic stiffness properties. These elastic properties or elastic coefficients can be determined by measuring the velocities of propagation of various ultrasonic waves. Lamb waves, for instance, propagate in paper and appear to be sensitive to paper strength. Experiments have been conducted with a laser‐based system to both generate and detect ultrasonic Lamb waves in copy paper. Results obtained regarding the relationship between the generation laser spot size, power density, and ultrasonic signal strength are presented. Paper damage is assessed at the generation spot. Phase velocity dispersion curves are produced for those modes that have sufficient signal‐to‐noise ratio. These dispersion curves are then compared to those predicted by ortotropic plate theory. [Work supported by OIP‐GT.]