In the Preface to this book, the authors state that it "was written to provide an introduction to the principles of acoustics for those students who have little or no background in engineering. The material is especially directed to students in speech and hearing sciences, although those in other health-related fields and theater arts may also find the approach useful." We are therefore forewarned that this is a very elementary text, and (possibly) restricted to audio and airborne sound.The first four chapters of the book are devoted to the presentation of periodic motion and wave phenomena and the presentation is almost completely nonmathematical. It therefore provides little base for treatment of more complicated situations in the later chapters.In Chap. 5, the authors present an almost nonmathematical analysis of vibrating systems, working mainly with a series of tables. There is a presentation of a Helmholtz resonator without much comment as to its potential usefulness in analysis.My dissatisfaction with the mathematical or, rather, nonmathematic treatment grew greater in this chapter. Two thirds of a page, plus six equations, is used to develop the idea that frequency is equal to sound velocity divided by wavelength. Then, after that extremely elementary treatment, the authors proceed to a description of speech production that, while descriptive in nature, is carded out at a much higher level. There is a detailed drawing of the larynx, plus a schematic diagram of the vocal mechanism, but the connection between the text and the diagrams was inadequate for this reviewer. The chapter ends with the introduction of such concepts as formants, plosives, stops, and fricatives. The first is introduced with no direct definition but the others are explained with considerable care and clarity.The chapter on the ear and hearing is rather well done, except that a better connection between text and some of the drawings would have been useful.Chapters 8 and 9 concern themselves with the physical side of acoustics, electroacoustics and sound measurement. These introduce the student to simple electric circuits, microphones and loudspeakers, as well as various aspects of sound pressure levels and measurements in very gentle fashion. The problem of combining sound levels is treated in reasonable detail. Problems of room absorption and noise reduction are also treated carefully, and in elementary fashion. There are many caricature drawings in the book, some of them not very clear (photographically). These are apparently aimed at lightening a subject that the student might find heavy. My own feeling for the work is that it oscillates between an introduction to the subject at a junior college level, to a presentation that is closer to that of elementary school. This unevenness is not an asset, in my opinion. The book does contain about 15 pages of definitions of acoustical terms, and has a large number of references where the student can pursue the subject further. Both of these are real assets to the text. xvi 4-334 pp. ISBN.' 2-...

Laboratory measurements have been made of the permeability (k), free porosity (ϕL), compressional velocities (VP or VE), and compressional attenuations (QP or QE) in Fontainebleau sandstone over a continuous range of porosities ϕ from 3 to 28%. This large variation was achieved without any composition change: Fontainebleau sandstone is made of fine quartz grains with regular grain size (≈250 μm). Permeability was measured with a falling head permeameter. Velocities and attenuations were obtained either through an ultrasonic experiment for frequencies around 500 kHz or through a resonant bar technique experiment for frequencies around 5 kHz and in both cases with varying water saturation. The results show an excellent correlation between permeability k and total porosity ϕ for all our samples. For low porosities (ϕ = 3% to 9%), permeability (in millidarcies) is 2.75×10−5(ϕ)7.33, while for high porosities (ϕ = 9% to 28%), permeability k (in millidarcies) is given by 0.303(ϕ)3.05. The correlation is also excellent between free porosity and total porosity. On the other hand the correlation between acoustic properties and total porosity is not as clear as for hydraulic properties whatever the frequency (500 kHz or 5 kHz) or the water saturation. On the average, velocity decreases, and attenuation roughly increases with increasing total porosity. Velocity and attenuation values are related to the variation of grain contact structure, and two samples with the same porosity and permeability may exhibit different velocities and attenuations. The clear correlation between hydraulic properties and porosity is related to constant grain size, while the lack of correlation for acoustic properties emphasizes the importance of the microstructure.

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A new analytical solution is presented for the laboratory pulse decay permeability problem. With this solution, pulse decay permeability problem. With this solution, permeability of a core sample can be calculated from the permeability of a core sample can be calculated from the decay rate of a pressure pulse applied to one end of the sample. This development permits rapid. accurate measurement of permeability in samples such as tight gas sands, limestones, and shales. Introduction Because of its usefulness in measuring very low permeability. the pulse decay technique has been permeability. the pulse decay technique has been discussed often in the literature. In this technique, a small pore pressure pulse is applied to one end of a jacketed sample, and the pressure vs. time behavior is observed as the pore fluid moves through the sample from one reservoir to another. Brace et al. cave an approximate solution to this problem with the assumption of a linear pressure gradient at all times. This simplification leads to a predicted exponential pressure vs. time decay. By means of numerical solutions, Lin and Yamada and Jones have shown that the Brace solution can lead to significant errors in calculating permeability. These numerical solutions. however. are inconvenient to use and require considerable computer programming time. We present an analytical solution based on realistic assumptions and boundary conditions. Experimental Technique To understand the theoretical problem more thoroughly, a short description of the experiment is desirable. Fig. 1 is a schematic of the system. Initially, both valves are open and pressure is constant throughout the system. Next, Valve 1 is closed, and the pressure is changed slightly in the large Reservoir 1. Valve 1 remains closed for a few minutes to allow thermal effects to diminish (particularly important if the pore fluid is (as). Valve 2 then is closed, and, at time equal zero. Valve 1 is opened. A small differential pressure between the reservoirs will be indicated by the p transducer and will decrease with time. Pressure in Reservoir 1 remains constant during the decay. After the differential pressure has decreased by approximately 20%, Valve 2 is opened to terminate the decay. This accelerates the equilibration of pressure so that the next measurement can be made. pressure so that the next measurement can be made. Theory As stated earlier, the pressure in Reservoir 1 remains essentially constant during the decay (t 0) because the volume of Reservoir 1, V1, is much greater than the pore volume, Vp, or the volume of Reservoir 2, V2. It can be assumed that fluid viscosity, is independent of position, x, in the sample and that fluid density, p, position, x, in the sample and that fluid density, p, permeability, k, and porosity, are dependent only on permeability, k, and porosity, are dependent only on fluid pressure, P. By combining Darcy's law with the one-dimensional diffusion equation we obtain ,..................(1) where B is fluid compressibility, Bs, is rock compressibility, and Bk is the dependence of permeability on pore pressure. The magnitude of the nonlinear terms pore pressure. The magnitude of the nonlinear terms with respect to the linear ones is equal to (Bk + B)P0, where P0 is the pressure pulse amplitude. Because (Bk - B ) = 10 -2 bar - 1 (Ref. 8) and P0=1 bar, the product is small, and, hence, nonlinear terms can be product is small, and, hence, nonlinear terms can be ignored. If we further assume that the equation of flow is ------- = --- --------, ......................(2) SPEJ P. 719

TARIF, P. and BOURBIE, T. 1987, Experimental Comparison between Spectral Ratio and Rise Time Techniques for Attenuation Measurement, Geophysical Prospecting 35,668-680.Two techniques for the measurement of attenuation-spectral ratio and rise time techniques-were tested and compared in the laboratory. The spectral ratio technique proved to be reliable and easy to implement for intermediate values (5 < Q < 50) of attenuation. For low (Q > 50) and high attenuations, the spectral ratio technique is inaccurate. Calculating the rise time on simulated signals, we found a relation between rise time z and the ratio traveltime to quality factor T/Q which could be approximated in intervals by the linear relation z = zo + C*T/Q. The constants zo and C depend on the absolute value of T/Q and on the initial source signal. The rise time technique, performed on the first quarter period of the signal, enables high attenuations (Q < 5 ) to be measured. The determination of the relation between z and T/Q is possible if one knows the initial source. We theoretically approximate this relation through a simulation using a realistic propagation model. With laboratory measurements made on Fontainebleau sandstone, we show that the rise time technique using the theoretical relation z = z(T/Q) gives comparable values of Q to those obtained from the spectral ratio technique. In borehole seismics, where it is often difficult to remove undesired signals, the rise time technique applied with the right (7, T / Q ) relation is the best method to use.