bluuebunny/crossref_metadata_2025 huggingface dataset:
A personal philosophy of design for noise control in ships
Authors: Baylis J. R.
Published: October 2005

This personal philosophy has evolved from eight years of active participation in the research and the design of Navy ships for controlled noise characteristics. The design for the control of noise begins with the establishment of requirements. Noise specifications must serve an understandable operational purpose that can be communicated to the many people that will design and build the ship. The requirements must be capable of being met within the state of the art, and at a cost that is commensurate with the value of the noise control. The cost must be acceptable to the producer as well as the customer, and the producer must understand from the beginning the amount of engineering and test that he is committed to. The techniques for controlling the noise of ships are well known, but there are choices to be made for those techniques to be used in construction, and those that can be used to come up to specification after test. An allowance should be made for the cost of test and for the cost of corrections to be made after test.
U.S. merchant ship noise: Recent measurements and proposed criteria
Authors: Gales R. S. , Jones D. T.
Published: October 2005

To provide guidance in the regulation of noise on U.S. merchant ships, noise levels and octave-band spectra were measured on seven ships of the U.S. Merchant Fleet. Ships selected included tankers, ore carriers, general cargo, and container ships; with steam turbine, gas turbine, and diesel propulsion. They ranged in size from 8000 to 36 000 gross tons and in construction date from the 1920's and 1970's. Locations measured included machinery and engine rooms, passageways, berthing spaces, mess and recreation spaces, bridge, radio room, and offices. Noise exposures based on measured sound levels and time spent in various spaces were calculated for individual crew members in various occupational categories. Exposures are compared with various criteria for hearing conservation, including the 24-h equivalent continuous sound level (Leq 24). A-weighted sound levels in other ship spaces are compared with various function-based criteria, such as speech communication, hearing of warning signals, rest and relaxation, and recovery from temporary hearing loss. Recommended criteria for A-weighted sound level on U.S. Merchant vessels are presented for immediate use and future goals.
Pressure sensitivity amplification in interferometric fiber optic hydrophones
Authors: Hughes R. , Jarzynski J.
Published: October 2005

The induced optical phase change when a pressure is applied to a fiber optic hydrophone is examined both theoretically and experimentally. The induced phase change is calculated both with and without a plastic jacket around the glass fiber. It is shown that the phase change predicted from a detailed three-dimensional analysis can be adequately described in terms of the much simpler two-dimensional generalized plane strain approximation. Sensitivities calculated assuming hydrostatic boundary conditions are shown to correspond closely in value with static pressure-sensitivity measurements. The application of a plastic jacket can substantially increase the pressure sensitivity of the fiber. The increased phase shift is due primarily to the tendency of the jacket to increase the axial strain experienced by the glass fiber. It is predicted that maximum pressure sensitivity (up to 30 times that of the bare fiber) will be achieved by jacketing with Teflon.
Studies of PVF2 transducers
Authors: Carome E. F.
Published: October 2005

Thin film polyvinylidine fluoride (PVF2) polymer transducers are being used for various applications over the frequency range 0.2 to 30 MHz. Operated in the thickness mode, they have been employed as sources and detectors of longitudinal and surface waves. Wideband impulses are easily generated and detected with these elements, so that a transducer's performance can easily be evaluated by examining its direct and Fourier transformed response. Detailed data are presented on the sensitivity, frequency response, and other characteristics of various PVF2 transducer configurations. [Work was partially performed at Stanford University and supported by ONR.]
Utilization of semiconductor strain gauges in pressure gradient sensor designs
Authors: Cuomo F. W. , Hilliker D. J.
Published: October 2005

The performance of a pressure gradient sensor of the fixed baffle type embodying semiconductor strain gauges is discussed. The output is optimized by the utilization of a bridge circuit providing good linearity and temperature compensation. Experimental data are obtained by means of a low-frequency acoustic calibrator similar in design to an earlier device [T. H. Ensign, J. Acoust. Soc. Am. 50, 108(A) (1971)] and compared with identical gradient transducers employing ceramic elements.
Serial-parallel architecture for real-time synthesis of music
Authors: Ferretti E.
Published: October 2005

Parallel architecture is extremely suitable for the synthesis of music. For example the performance of several instruments at the same time is a directly related task for parallel architecture. Serial architecture on the other hand is ideally suited for optimizing real-time tasks. The reasons for serial-parallel architecture are (1) to utilize a single-type module for computing all tasks in real time, (2) to have a means of adjusting the number of tasks without changing the basic system or violating real-time requirements, and (3) to have a means of computing time waveforms which require a large amount of transcendental functions for approximating natural sounds. This paper will discuss the issues of system configuration, accuracy, dynamic range of output versus computation, multiple instruments, and modeling of natural sounds for computer music. Some examples of computer music will be presented, and a high-speed film of a vibrating rubber band will be shown. [This work was supported in part by a private grant from Michael Lay, and use was made of computer facilities in the Computer Science Department.]
Dumb ways to play intelligent instruments
Authors: Mathews M. V.
Published: October 2005

In the last five years a new generation of digital instruments has been developed using the new integrated circuit technology. In contrast to previous digital instruments, which were confined to studios, these new instruments are small enough, cheap enough, portable enough, reliable enough, and powerful enough to form a new class of performance instruments. In addition to sound synthesis circuits, they include mini- and microcomputers with general computing power and with digital memories. Because of their computational power, we call them intelligent instruments. Musicians must learn very different performance techniques to take advantage of the potential of these instruments. In this paper we review some of the initial ways in which the instruments have been played. We conclude that although many of the performances are interesting, much must be learned before the full potential of these instruments is utilized.
Sequential drum
Authors: Mathews M. V.
Published: October 2005

A sequential drum is described. It consists of a square surface 20″ by 20″ which is hit with conventional drum sticks. Transducers on the surface generate three electric signals each time the surface is hit. One signal is a pulse whose amplitude is proportional to the impact. The other two signals encode the x and y positions of the stroke. The three signals are transmitted to a digital sound synthesizer (Alles machine) which generates a note each time a signal is received. The loudness of the sound is controlled by the amplitude pulse. The timbre of the sound is controlled by the x and y signals. The pitch of the sound is obtained from a score stored in the memory of the digital synthesizer. Each time the drum is struck, the next pitch in the score is played; thus, the desired sequence of pitches is produced automatically by the instrument.
Musical spectroscopy I: The real-time power spectrum in instrument and voice teaching
Authors: Potter Charles E. , Teaney Dale T.
Published: October 2005

We have explored the uses of a real-time sound color “machine” in the music studio environment. The spectral analysis is performed by a 512 line, 33-ms FFT instrument; the output of which is sampled every 65 ms at a logarithmically uniform density of 96 points/8va and stored in one of two 512- × 10-bit buffers. The 5-8va spectra are displayed as graphs one above the other. The rms scale is well suited to a single instrument. A piano keyboard graphic underlines each spectrum. In operation, a model spectrum by the teacher or from a recording is captured by action of a foot switch; the student then observes his own spectrum, running in real time or frozen, on the graph below the model. The spectrometer provides a graphic notation that relates the kinesthetics of production behavior to the acoustic properties of the instrument on the one hand and to the aural penetration of the sound on the other hand. A change of vowel, an alternate fingering, or the influence of a mute is usually enough for the student to get the idea of what the display means to him, and “the machine” then becomes a sort of recording secretary in the performance training dialog.
Results of monitoring of noise and air quality in feeder areas at various proximities to freeways for matched groups of school children
Authors: Swing J. W.
Published: October 2005

Community noise levels throughout feeder areas serving 16 grammar schools in the Los Angeles County School District were monitored in order to determine the environmental noise exposure experienced by 3rd and 6th graders in socioeconomically matched groupings. Schools for this study were selected such that the noise environments for one-half of the feeder areas would be largely controlled by freeway traffic noise. Noise monitoring at school sites within each feeder area was also conducted. Additionally, indoor and outdoor air quality monitoring was conducted on a rotational basis during December 1978 and January 1979 at each school site. Estimates of each feeder area's relative air quality have been extrapolated from the school studies which were in turn correlated to South Coastal Air Basin air quality data. Community noise levels, based upon approximately 350 site days of monitoring, are presented along with each feeder area's socioeconomic and ethnic population descriptors. The influence of freeway proximity on environmental noise levels and ambient air quality is discussed.
Unmanned noise source identification via analog tape microsampling
Authors: Watson Hal , Holman Jim
Published: October 2005

A new method of analog tape microsampling is discussed. The method centers about a controller which turns the analog tape recorder on and off at a low sample rate at low sound levels and at a high sample rate at sound levels above a preset threshold. Results of its application to airport/aircraft/community noise environments are discussed with regard to accuracies of level statistics and source identification.
Sound propagation in colloidal suspensions in electrolytes
Authors: Gültepe M. E. , Barrett-Gültepe M. A. , Yeager E.
Published: October 2005

The propagation of ultrasonic waves through colloidal suspensions in electrolytes is of interest from the standpoint of understanding sound propagation in the sea and in biological systems, and as a means for study of colloidal systems. Ultrasonic velocity and absorption measurements have been carried out in suspensions of particles of various configurations, including polystyrene latex (monodispersed spheres of, e.g., 5500 Å), kaoline (sodium form, platelets), montmorillonile (sodium form, platelets), and microcrystalline cellulose (rods) over a range of suspensions concentrations at several frequencies. The velocity changes associated with the colloid occur principally because of the difference in static adiabatic compressibility of the colloid phase and bulk electrolyte. With very small particle size—high surface area system, the change in compressibility of the solvent molecules adsorbed on the colloid surfaces may also be significant. The principal factors contributing to the additional absorption are relative motion losses, thermal conductivity across the interfaces, an ionic double layer, and adsorption-desorption relaxation. Particle-particle interactions must also be taken into account in the more concentrated suspensions. [Research supported by ONR.]
Sound velocity versus temperature measurements in tissues
Authors: Jacobs Steven R. , Christensen Douglas A. , Rockhold Steven A. , Johnson Steven A.
Published: October 2005

We have developed a sensitive interferometric technique for measuring the variation of the velocity of ultrasound in tissue as a function of temperature. The tissue samples are placed between two transducers mounted in an invar holder, and this assembly is situated in a temperature-controlled water bath. The transmitting transducer is excited continuously by a crystal-controlled oscillator at a frequency of 10 MHz. The phase of the received signal is compared with the phase of the transmitted signal by a vector voltmeter. Variations in velocity are detected as changes in the relative phase between the transmitted and received signals. The overall accuracy of the system allows resolution to within 3° of phase difference. This corresponds to an accuracy of 10 ppm for a transducer spacing of 10 cm. The experimental data will be used in a larger project aimed at measuring internal body temperature nonintrusively with computer-aided tomography. Temperature resolution on the order of 0.1°C across 1 cm of tissue are expected in the final instrument.
Nearfield of ultrasonic transducer-lens systems: Comparison of experiment and theory
Authors: Edwards P. L. , Cook Bill D. , Dardy Henry D.
Published: October 2005

Local acoustic pressures in the nearfield of ultrasonic transducer-lens systems were determined by measuring the scattering from a microsphere scanned through the field. The lens was placed both adjacent to and separated by a distance of one focal length from the transducer. Typical parameters were the following: frequency 5.0 MHz, transducer diameter 0.5 in., focal length 1.0 in., diameter of microsphere 0.002 in. Experimental results show remarkable comparison with the details predicted by the Gaussian-Laguerre formulation presented elsewhere in this meeting. [This research was conducted at the Naval Research Laboratory, Physical Acoustics Branch, Washington, DC.]
Studies of acousto-optic interactions in optical fibres
Authors: Carome E. F. , Koo K. P. , Schmidt P. B.
Published: October 2005

Studies are continuing of acoustically induced phase and intensity modulation of light beams propagating in optical fibres. A fibre element submerged in water is irradiated with plane acoustic waves. The optical field exiting from the output end of the fibre is precisely scanned. Acoustically induced changes in the output pattern are being examined in an effort to obtain information on fibre mode-mode coupling and other phenomena. Details of the measurements and recently obtained experimental results are presented. [Work supported in part by ONR.]
Acoustic emission from leaking values
Authors: Dickey J. W.
Published: October 2005

The acoustic emission associated with leakage through air, steam, hydraulic, and water valves has been investigated. Experiments were performed to determine what characteristics of the acoustic emission may be related to leak rate with the hope that instrumentation could be developed to acoustically detect and measure leakage. The spectral and temporal characteristics of leakage-associated signals taken from externally mounted detectors or valves indicate that average acoustic amplitude in selected frequency ranges provide a useful measure of valve leakage for most styles of air, steam, hydraulic, and water valves. The existence of cavitation in water and hydraulic fluid complicates leakage measurement and, for hydraulic fluid, the sum of event amplitudes multiplied by their rate of occurrence results in a value which increases with increasing leak rate. The data collection and analysis used to support the conclusions are discussed.
A mode of peripheral auditory processing
Authors: Houde R. A. , Bancroft J. C. , Parkins C. W.
Published: October 2005

A model of peripheral auditory processing was developed to guide the experimental design of a multichannel cochlear implant. The model specifies the neural processing necessary to represent observed PST histogram behavior of single eighth-nerve neurons and its relationship to the design of a multichannel vocoder processor. The model includes electrical characteristics of the cochlea. Simulation studies of stimulation characteristics are reported.
Two-tone suppression in the auditory nerve of the cat: Suppression thresholds and rate of growth
Authors: Javel Eric
Published: October 2005

Our previous work has been directed at elucidating the behavior of the two-tone suppression phenomena when both tones are excitatory. Analyzing the phase-locked response of fibers possessing low characteristic frequency (CF), we have shown [E. Javel, J. Acoust. Soc. Am. Suppl. 1 65, S83(A) (1979)] that suppression exists throughout an auditory nerve fiber's response area and that the ability of an excitatory tone to suppress the response to another excitatory tone is similar to a nonexcitatory tone's ability to suppress. For a given suppressor-tone intensity, suppression is maximal when the suppressor tone lies near fiber CF, and suppression magnitude is reduced on either side of CF. The contours relating suppression magnitude to frequency are similar in shape, but not in extent, to the isointensity response contours observed in determinations of response area. The “threshold” for suppression is systematically related to fiber sensitivity at the suppressor-tone frequency, but it is always greater or equal to the pure-tone threshold at that frequency. Threshold for suppression is not related to the threshold for the tone being suppressed. Once the threshold is exceeded, suppression for both excitatory and nonexcitatory tones grows with increasing suppressor-tone intensity in a manner consistent with that described by Sachs and Abbas [J. Acoust. Soc. Am. 60, 1157–1163 (1976)]. The final slope of the curve relating suppression magnitude to suppressor-tone intensity is near unity for suppressor frequencies near fiber CF, but is usually greater than one for suppressors much lower in frequency than CF and less than one for suppressors higher in frequency than CF. Suppression does not saturate at high intensities, but in many instances its magnitude is obscurred by the “notch” often seen in single-tone rate-intensity functions [Kiang et al., J. Acoust. Soc. Am. 46, 106(A) (1969)], i.e., the “notch” cannot be suppressed. [Work supported by NIH.]
AP tuning curves and anatomical correlates from acoustically traumatized cats
Authors: Shepard N. T. , Abbas P. J.
Published: October 2005

Compound action potential tuning curves, using a forward-masking paradigm, were developed on both a control group and a group of acoustically traumatized cats. Differences observed between the two populations included a decrease in the sharpness of the tip, in the sensitivity of the tip, and/or in the sensitivity of the tail region. Phase contrast light microscopy was performed on all exposed ears using a celloidin embedding technique with horizontal sectioning. Whenever an abnormality in an AP tuning curve was seen, histological evidence of damage to the organ of Corti in an appropriate region corresponding to the signal frequency was observed. However, several cases of damage to the cochlea were observed with normal tuning curves. Wherever the tip region of the tuning curve was elevated, evidence of damage to all three rows of OHC and to the IHC was seen. Several other observations relating to the extent of damage to the OHC and IHC independently were found to be similar to results from single-fiber recordings in acoustically traumatized cats [M. C. Liberman and N. Y. Kiang, Acta Otolaryngol. Suppl (STOCKH) (358). 1–63 (1978)].
Some new causes of acoustic impedance change during acoustic stimulation in man
Authors: Singh V. R.
Published: October 2005

Investigation of the actual nature and causes of the acoustic impedance change during acoustic stimulation in the ear has been an active area in the recent past. It is believed that the impedance change is only due to the middle ear muscle activity, but according to the present investigation, this is not true. The acoustic impedance has been studied with and without ipsilateral sound stimulus by using an electroacoustic bridge technique in living human ears, temporal bones, and mechanical models of the ear. The change in the acoustic impedance is also found in denerved cadaver bones and mechanical ears. This clearly shows that the muscle activity is not the only cause, but some new causes like physiological characteristics of the eardrum, anatomical structures of the ear, local induction phenomenon in the ear, and compliance of the eustachian tube are also responsible for the acoustic impedance change during the sound stimulation. The present study is useful in investigating the actual nature and causes of infections and diseases of the ear. [Work supported by Canadian Commonwealth Scholarship and Fellowship Committee.]
Prediction of noise in ships by the application of “statistical energy analysis.”
Authors: Jensen John Ødegaard
Published: October 2005

If it will be possible effectively to reduce the noise level in the accomodation on board ships, by introducing appropriate noise abatement measures already at an early design stage, it is quite essential that sufficiently accurate prediction methods are available for the naval architects. In general, the structure-borne noise contribution from the various noise sources may be precalculated with a reasonable accuracy using empirically based calculation models. The prediction very often fails, however, when the empirically based calculation model is applied for an untypical structure or for a special noise abatement measure, e.g., increased structural damping. The paper discusses whether it might be possible to derive an alternative calculation model based on the “statistical energy analysis” approach (SEA). By considering the hull of a ship to be constructed from plate elements connected by combination of L junctions, T junctions, and cross junctions, a SEA-calculation model has been derived. Examples on application of the SEA model for prediction of the structure-borne sound transmission are given, partly through simple two-element structures consisting of stiffened and unstiffened plate panels, partly through a hull section consisting of several stiffened plate sections. The results of the SEA calculations are compared with corresponding results of vibration measurements on the structures.
The airborne path in shipboard noise control
Authors: Junger M. C.
Published: October 2005

Reverberant noise in living and working spaces other than the machinery room is typically controlled by structure-borne paths. However, as machinery vibration isolation and foundation damping techniques are perfected, airborne flanking paths discussed in this paper become increasingly important. In contrast to representative masonry walls, the finite extent of shipboard partitioning and bulkheads is an essential factor in determining transmission loss (TL). Consequently, structural damping is beneficial not only near coincidence, but also at higher frequencies. A second distinguishing feature of much shipboard partitioning is frame stiffening. This extends the beneficial effect of damping to frequencies below coincidence. Stiffening frames cause marked TL degradation below the TL of the underlying uniform plate, in spite of the latter's smaller mass. In conclusion, the concept that mass per unit area is the single most important factor in determining TL is not relevant to the shipboard situation.
Control of shipboard airborne noise caused by propeller cavitation with a naturally aspirated compliant air layer
Authors: Gray Leslie M.
Published: October 2005

Propeller cavitation can often be a severe source of shipboard airborne noise, especially in after spaces on high-speed or high-powered vessels. Control of this noise source is difficult since the cavitation imparts vibration energy to major hull structure. Typical noise control of this source usually involves such treatments as damping. isolated decks and bulkheads, and added mass. Unfortunately, this additional weight is often unacceptable to the ship designer. This paper investigates control of this source by introduction of a compliant air layer between the water and the hull structure, which will act as a simple springlike isolator. The potential effectiveness of this compliant air layer is outlined. A source of air is proposed which employs the negative pressure reduction due to flow over an emitter on the hull to suck atmospheric air into the ship's boundary layer. An example design is presented for a high-speed yacht which will provide adequate air for substantial reduction of propeller-airborne noise for vessel speeds over 15 knots.
Perceptual equivalence of cues for a phonetic trading relation: Primacy of phonetic over psychoacoustic effects
Authors: Best Catherine T. , Morrongiello Barbara , Robson Rick
Published: October 2005

Recently a phonetic trading relation was found for two different cues to the identification of [split] versus [slit], namely, silent closure duration versus initial formant transition differences for the [plit]-[lit] contrast. Within limits, varying either cue produces the phonetic contrast; an extra amount of one compensates for lack of the other. [Erickson, Fitch, Halwes, and Liberman, J. Acoust. Soc. Am. Suppl. 1 61, S46(A) (1977)]. Subsequently, a three-way discrimination test was devised to more clearly show that the phonetic effects of the independent cue manipulations are perceptually equivalent [Fitch, Halwes, Erickson, and Liberman, Haskins Laboratories: Status Report (1979)]. The researchers hypothesized that the trading relations and perceptual equivalence phenomena reflect perceptual specialization that takes account of the common origin of cues in single articulatory gestures. But the phonetic generality of the paired phenomena needs assessment; therefore, we used their procedures to test the simpler [stay]-[say] contrast. Both phenomena were replicated and virtually identical in magnitude to those reported earlier. To test the phonetic specificity of the phenomena, we ran a perceptual equivalence discrimination test with nonspeech sine-wave analogs of the stimuli, using naive subjects. Results suggest that, in perceiving stimuli, speech sharply increases the effectiveness and shifts the absolute value, of a weak psychoacoustic boundary. [Work supported by NICHD.]
Difference limens for fundamental frequency contours in sentence level stimuli
Authors: Harris M. S. , Quinn A. M. S.
Published: October 2005

Two experiments were performed to measure the difference limen (DL) for fundamental frequency using sentence level speech stimuli. In experiment I a male reader recorded five sentences. They were analyzed and synthesized using a linear prediction vocoding system. Part of each sentence was varied in 5-Hz steps above and below the original contour. Sentences (original contour and one of the changed contours) were presented to listeners using the method of constant stimuli. DL's ranged from less than 5 to 15 Hz depending on the sentence. There was no significant difference between DL's as a function of direction of change (up or down from original). Experiment II was an attempt to determine if the variability in DL due to sentences was a function of differences in placement of the frequency change. The changes in fundamental frequency began and ended at voiceless portions in all sentences. The median DL for the speaker also used in experiment I was 12 Hz. No significant differences as a function of sentences were found. For another speaker the DL's were over 15 Hz.
Adaptation of speech by nonspeech: Evidence for complex acoustic cue detectors
Authors: Samuel Arthur G. , Newport Elissa N.
Published: October 2005

Three selective adaptation experiments were run, using nonspeech stimuli (music and noise) to adapt speech continua ([ba]-[wa] and [cha]-[sha]). The adaptors caused significant phoneme boundary shifts on the speech continua only when they matched in periodicity: Music stimuli adapted [ba]-[wa], whereas noise stimuli adapted [cha]-[sha]. However, such effects occurred even when the adaptors and test continua did not match in other simple acoustic cues (rise time or consonant duration). Spectral overlap of adaptors and test items was also found to be unnecessary for adaptation. The data support the existence of auditory processors sensitive to complex acoustic cues, as well as units that respond to more abstract properties. The latter are probably at a level previously thought to be phonetic. Asymmetrical adaptation was observed, arguing against an opponent-process arrangement of these units. A two-level acoustic model of the speech perception process is offered to account for the data.
Acoustical evaluation and control of normal room modes
Authors: Bonello Oscar J.
Published: October 2005

Analysis of a new criterion for the correct distribution of normal room modes is presented. This criterion replaces unsuccessful earlier ones. It is based on the resonance modes density curve related to one-third octaves. A computer program, easy to perform, allows to obtain the best dimensional ratio of the room, to avoid sound coloration. This method was duly verified, applying it to the calculation of the dimensions of a high number of existing studios considered of excellent quality and of others with evidence of coloring. The correspondence of theoretical and practical conclusions was very good. As second step, it will describe a special device for acoustical absorption. This resonant absorber is frequency selective with high absorption in the low-frequency end, remaining low and constant beyond 2000 Hz. By means of a computer program, the spatial distribution of the isolated room modes can be plotted. It allows to place the absorption devices in the exact position to obtain maximum control of each mode.
Sound transmission loss of windows
Authors: Quirt J. D.
Published: October 2005

An extensive series of measurements has been made to obtain a systematic evaluation of the effects of glass thickness and interpane spacing on the sound transmission loss of windows. These included 93 laboratory measurements conforming to ASTM standard E90 and field measurements on a subset of 18 of these window types. The samples studied included glass thicknesses from 3 to 6 mm and interpane separations from 6 to 150 mm. In addition, the effects of absorptive treatment, cavity dividers, and nonparallel glass surfaces were investigated. The data contradict one widely held belief about window design.
Consulting on more than a building a day
Authors: Drommond David E.
Published: October 2005

Acoustical Engineers are normally able to spend considerable time analyzing a room in order to provide a satisfactory acoustical space; however, such time cannot be spent when faced with the large number of buildings that the Church erects each year. Designs must be “mass produced,” yet each building should also receive individual attention. Standard acoustical practices have been modified to meet these peculiar needs. This paper summarizes the design. review, construction, and inspection phases of a typical meetinghouse designed for the high volume mode.
Benjamin Bauer's contribution to audio and acoustics
Authors: Abbagnaro Louis A.
Published: October 2005

Benjamin Bauer worked actively in Audio and Acoustics for over 40 years. He made contributions in the areas of engineering acoustics, psychoacoustics, and underwater acoustics. This paper will describe selected major topics in those areas which are still of interest today.
Amplitude and phase accuracy of broadcasting microphones
Authors: Abbagnaro Louis A.
Published: October 2005

Phase and amplitude accuracy of microphones can influence the quality of recorded programs. These effects have become more pronounced as multichannel recording has become an accepted format, and they can degrade both the frequency response and spatial accuracy of the information. Techniques to overcome such problems, include special microphone designs such as multielement microphones, “sound field” microphones, and the use of artificial heads. Strengths and weaknesses of several approaches are reviewed.
Digital technology and acoustical accuracy in domestic music reproduction
Authors: Berkovitz Robert
Published: October 2005

Accuracy of spectral magnitude measurement is a generally accepted criterion of sound reproduction ability, but there is little correspondence between the conditions under which usual loudspeaker measurements are made and the realities of loudspeaker usage. It is also unclear whether specific programs are intended for field reproduction, in which the listening environment is cancelled, or source reproduction, from which the recording environment is absent. The achievement of either objective depends upon (1) the use of loudspeakers which meet certain directivity criteria and (2) new transmission systems which may be suitable applications of digital encoding. Loudspeaker measurements which employ digital signal processing may aid the design of such loudspeakers and transmission systems by allowing (1) acquisition of binaural data in actual room settings, (2) observation of the response of linear basilar membrane models to real sources, (3) extraction of useful interaural cross-correlation data, and (4) separation of room effects from those of direct source radiation. Examples of such measurements are shown.
Elements of quality variation: voice modes and singing
Authors: Colton R. H. , Estill J.
Published: October 2005

In this presentation, the results of several experiments on voice quality will be reviewed. In all these studies, the subjects produced four perceptually distinct voice qualities on each of several fundamental frequencies throughout the whole phonatory range. In one experiment which tested the perceptual distinctiveness of each quality, observers were presented stimuli from which all but spectral cues had been eliminated. Observers were able to recognize the four qualities even at extremes of fundamental frequency. Analyzed acoustically, the four qualities are distinguished by frequency bandwidth, location of resonant peaks, spectral envelope, and dynamic range. Physiologically, each quality is characterized by specific behaviors in the larynx and within the vocal tract. In one, the vocal tract is very large, and the vocal folds appear to approximate with very little mass and with a very short closed phase. In another, the pharynx is small, with rapid opening and closing of the vocal folds. In yet another quality, the vocal tract is very small, with a peculiar configuration of the supraglottal structures. These and other observations are indicative of the differences among these qualities. Each quality represents a particular set of the vocal mechanism or mode of voice use. From the results of more recent experiments, we have developed the concept of voice modes to be unique sets of perceptual, acoustic, and physiological elements. These elements in the perceptual domain, for instance, are very much like distinctive features, except that they are probably not binary phenomena. Depending on the type of combination and the degree to which they are used, these “voice quality features” can be used to specify the voice quality. This concept will be discussed in this paper. Voice modes and the concept of distinct physiological, acoustical, and perceptual features should be useful and meaningful to any singer. With these concepts, he or she can quickly learn the proper antecedent physiological conditions necessary for a specified vocal quality. Once mastered, he or she can vary elements of the voice mode set to produce subtle or gross differences of vocal quality that can result in greater variety in performance.
Elements of frequency and amplitude modulation in the trained and pathologic voice
Authors: Shipp T. , Izdebski K.
Published: October 2005

Rhythmic changes in the frequency and/or intensity of the vocal signal during sustained phonation is characteristic of trained singers and individuals with some neurological dysfunction. The questions that are explored in this presentation are: (1) For the two groups, what aspect of the acoustic signal is being modulated? (2) Is the mean repetition rate similar for the two groups? (3) How regular are the cyclic variations in the signal between the two groups? and (4) What physiologic assumptions can be made about the origins of these phenomena? Acoustic analysis of sustained vocal output by ten professional opera singers producing frequencies throughout their vocal range and the sustained vocal phonation by selected patients from a population of spastic dysphonic individuals indicates two differences between the groups: Singers primarily vary the frequency of phonation ±0.5 semitone for vibrato, whereas the patients primarily varied signal amplitude. The mean rate at which the variations took place were the same for the two groups. The variability of cycle-to-cycle measures was extremely small in the professional singers and quite large for the patients. The vibrato rates obtained were substantially below those given as normal physiologic tremor rate. Similarity in the rates between the two groups suggests that the physiologic mechanism for vocal tremor and vibrato may be the same with the singers demonstrating an ability to inhibit the pulses in all muscle groups except for the superior laryngeal nerve innervating the cricothyroid muscle. Patients and, perhaps, less skilled singers demonstrate periodic muscle stimulation in sites throughout the vocal tract including the respiratory system.
Remote measurement of water currents using correlation sonar
Authors: Edward J. A.
Published: October 2005

In correlation sonar the relative velocity between a source/receiver platform and an ensemble of scatterers distributed over the transmit beam pattern is obtained from the spatial and temporal cross correlations over an array of hydrophones. With a two-dimensional array and suitably encoded transmissions, it is possible to measure the three components of the mean-velocity vector plus the variation within the resolution volume of the radial component. For remote current profiling, one can measure the velocity components in a water volume bounded in angle by the transmit beam pattern and in range by the signal waveform and integration window parameters using a simple monostatic array configuration. If desired, a complete velocity profile can be measured during each transmission cycle. This paper will review the basic theory of correlation velocity measurement and will discuss system design contraints and operating parameters and their relationship to such performance measures as volume and depth resolution, profiling range, and measurement accuracy. In addition, results from a limited number of in-water measurements will be presented. [Work supported in part by the National Oceanic and Atmospheric Administration.]
Doppler sonar measurements from FLIP
Authors: Pinkel R.
Published: October 2005

A pulse-to-pulse incoherent Doppler sonar has been developed at the Marine Physical Laboratory for use in the observation of oceanic internal gravity waves. Mounted on the Research Platform FLIP, the sonar transmits at frequencies between 65 and 90 kHz at a peak power of −32 kW. During preliminary tests, measurements have been made out to a range of 1.6 km, depths of 1.2 km, with a range resolution of 25 m. The sensitivity of the sonar measurements to a given internal wave group depends on both the orientation of the sonar beam and the direction of propagation of the wave packet. Since the vertical angle of wave propagation is a function of frequency, a predictable pattern can occur in sonar derived estimates of the interal wave frequency spectrum. These can be used to infer a limited amount about the azimuthal directional properties of the wavefield. A more direct approach is to use multiple sonars, operating simultaneously but pointed in different directions. A four sonar system is currently being constructed for use on FLIP. This should permit accurate estimates of azimuthal directionality of waves up to kilometer scales.
Ocean acoustic monitoring and multipath stability
Authors: Spindel R. C. , Spiesberger J. L. , Metzger K.
Published: October 2005

A procedure for remote sensing of mesoscale ocean dynamic processes has been proposed by Munk and Wunsch [Deep Sea Res., 26A, 123–161 (1979)]. It is based on the measurement of acoustic travel time variations between fixed sources and receivers distributed on the boundary of a large ocean area. Inverse theory is invoked to estimate the structure of the interior sound velocity field from travel time perturbations along individual ray paths. In this paper we present the results of a 48-day multipath stability experiment that demonstrates sufficient path stability to enable ocean acoustic remote sensing using this technique. A 220-Hz phase encoded signal with 64-ms resolution was transmitted at 10-min intervals between a moored source and a receiver at a 900-km range. Ray paths are clearly resolved, unambiguous, and identifiable. [Work supported by ONR.]
Remote acoustic sensing of fluid and biological processes in the ocean
Authors: Orr M. H. , Hess F. R.
Published: October 2005

A towed four-frequency acoustic backscattering system has been used to detect a variety of fluid processes in the ocean. A short review of experimental results obtained during the past three years will be presented. Examples of acoustic records which show detected short period internal waves, mixed processes, the seasonal variability of the particulate distribution and dispersion of man-introduced particles in the ocean, and interleaving water masses will be presented. Internal wave spectra calculated from the acoustic records will be discussed. Acoustic data showing the interrelationship of predator and prey, and active biological avoidance of research instrumentation will also be presented. [Work supported by NORDA, NOAA and NSF.]
Structure-borne noise transmission through ship stanchions
Authors: Burroughs C. B. , Fishcer R. W. , Shiflet F. L.
Published: October 2005

Stanchions provide a path for structure-borne noise transmission from a noise source space on one level to noise sensitive spaces on another level in commercial and combatant surface ships. Measurements of structure-borne noise from one level to an adjacent level were made with and without a stanchion in place in the laboratory full-scale model of ship compartments at Hopeman Brothers. Measured data of the structure-borne noise transmission loss across the stanchion and the difference in the airborne sound power levels radiated into the compartments with and without the stanchion in place are presented. Results of statistical energy analysis (SEA) are compared to measured data. Methods for reducing structure-borne noise transmission through stanchions are suggested.
Sodar studied atmospheric temperature inversions of the Salt Lake Valley
Authors: Davis G. , Dickson D. R.
Published: October 2005

Inversional temperature phenomena indigenous to Utah's Salt Lake Valley were observed and studied over a continuous time span of 28 days occurring in December-January 1976–1977. The phenomena were combined with local topographical barriers to maintain a situation of marked atmospheric stability in the lowest kilometer. The nonturbulent conditions resulting were commonly neutral in character, but composite conditions retained generally stable patterns of inversion genesis and disintegration. Particular attention was given to comparing available rawinsonde raw data (soundings) with their coincidental sodar counterparts obtained from the continuous record. Results implied a compatibility between two techniques of sensing used, one being a remote sensor, the other in situ. Best agreement was discovered in the inversion cases below 500 m and with those of stronger intensities.
Masking, temporal integration and speech intelligibility in subjects with noise-induced hearing loss
Authors: Tyler Richard S. , Fernandes Mariano , Wood Elizabeth J.
Published: October 2005

Three psychoacoustical measures of frequency analysis were obtained from ten normal-hearing subjects and twelve subjects with noise-induced hearing loss. First, thresholds of pulsed 500- and 4000-Hz pure tones were measured in the presence of a continuous, 60 dB/Hz spectrum level white-noise masker. Second, thresholds of pulsed, pure tones were measured in the presence of a continuous, 85-dB SPL tonal masker of 500 and 4000 Hz. Third, the intensity required to mask pulsed, 500- and 4000-Hz test signals at 10-dB sensation level was measured with sinusoidal masker of five adjacent frequencies [psychoacoustical tuning curves]. We also measured thresholds for 10- and 1000-ms duration signals of 500 and 4000 Hz as an indication of temporal integration. Two tests of speech intelligibility, one in a speech-spectrum shaped noise and one in a speech-babble background, were presented at a fixed intensity. Some hearing-impaired subjects clearly display increased thresholds in white noise (larger critical ratios), pronounced downward spread of masking, and flat or inverted tuning curves. Reduced frequency analysis and poor temporal integration were significantly correlated with reduced speech intelligibility in noise.
Comparison of intensity discrimination in normal hearing, cochlear impairment and hearing loss simulated by masking
Authors: Florentine M.
Published: October 2005

Intensity discrimination was measured as a function of level in normal hearing, cochlear impairment, and normal hearing with hearing loss simulated by masking. Both moderate flat losses and high-frequency sloping losses were studied. The stimuli were 500 ms tones with rise-fall times of 25 ms and interstimulus interval of 200 ms. Difference limens were based on several blocks of 100 trials using a two-alternative forced-choice procedure with feedback. In general, the high-frequency cochlear impairment and the high-frequency simulated loss show enlarged difference limens at levels below 90 dB SPL. However, one observer with a flat cochlear impairment showed enlarged difference limens throughout the entire intensity range, whereas the simulated flat losses show enlarged difference limens only in the range of recruitment. Interestingly, the difference limens are enlarged in the intensity range of abnormally rapid loudness growth. [Work supported by NIH.]
A male-female speaker interaction for speech discrimination in noise with elderly compared to college age listeners
Authors: Gengel R. W. , Marks M.
Published: October 2005

Speech discrimination was measured in quiet and in noise for 30 elderly and 30 college-age listeners using a recorded male and female speaker. Results indicated there were no differences in intelligibility between speakers for the quiet condition. In contrast, for the noise condition, the male speaker was approximately 12% more intelligible than the female for the elderly group but approximately 16% less intelligible than the female for the younger group. This relative difference of about 28 percent in discriminability between talkers for elderly compared to college age listeners indicates a strong interaction between speakers and listener groups. Some statistical analyses of the audiometric data from the elderly listeners and electroacoustic analyses of the speech of the talkers will be discussed in an attempt to account for the interaction effect that was found.