bluuebunny/crossref_metadata_2025 huggingface dataset:
Speech discrimination in deaf subjects with cochlear implants
Authors: Eddington Donald K.
Published: October 2005

Direct electrical stimulation of the auditory nerve is being considered as a way to provide information useful for speech communication in the profoundly deaf. Single-channel systems that tend to stimulate all fibers alike have had limited success in achieving this goal. Multichannel systems that can generate more complex temporal-spatial patterns of activity are now being introduced. Psychoacoustical experiments relating the parameters of cochlear stimulation to behavioral performance will be reviewed. One set of results using speech-like stimuli will also be presented. The stimuli used were synthesized vowels (/a/, /i/, /u/) and consonant-vowel (CV) syllables (/ba/, /da/, /ga/, /ta/). Vowel triads and CV triads were presented in an AXB discrimination task for several different speech processing schemes and for several different electrode configurations. Initial experiments using a four-channel system produced almost faultless discrimination of these stimuli. [Supported in part by NIH grants.]
Electric power plant environmental noise guide
Authors: Teplitzky Allan M. , Hickman Charles E. , Dubois T. James , Trykoski Michael A. , Paladino Robert C.
Published: October 2005

Increased public awareness on environmental noise has resulted in a need for a comprehensive guide for the abatement of noise emissions from electric power plants. The Edison Electric Institute, the principal organization of investor owned electric utilities, sponsored the development of the Electric Power Plant Environmental Noise Guide (Guide) which providing utility engineers, environmentalists, consultants and regulators with detailed information for predicting, evaluating measuring, specifying, and abating power plant noise emissions. The information used in the Guide was gathered from technical publications, standards, consultants' project files and EEI member companies, and represents the state-of-the-art of power plant noise data. The Guide contains information on the following topics: (a) a method for estimating expected community response to power plant emissions; (b) a method for making noise surveys; (c) relationships between noise emissions and significant design parameters of more than twenty types of power plant equipment; (d) properties of outdoor sound propagation, including the effects of local topography and meteorology; (e) a step-by-step procedure of predicting noise emissions from an existing or proposed power plant and a method for drawing noise contours of the yearly energy average A-weighted sound levels; (f) the effectiveness and relative costs of noise control treatments for major power plant equipment; (g) a methodology for ordering the potential environmental noise impact of major pieces of power plant equipment; and (h) information on consensus noise standard applicable to power equipment. The Guide was prepared for EEI by Bolt Beranek & Newman, Inc., under the direction of the EEI Environmental Noise Regulatory Task Force, and it is available from the Edison Electric Institute, 1140 Connecticut Avenue, Northwest Washington, DC 20036.
A program for power plant fan noise control
Authors: Graham J. B.
Published: October 2005

Fan noise has been identified as a significant component of power plant noise in recent years and, as a result, it is an important factor in the noise control analysis program for power plant work areas and the surrounding community areas. This paper evaluates the relative importance of this noise source and outlines a future program for heavy duty industrial fan noise control in power plant applications.
Noise control of power plant electrical equipment
Authors: Hribar A. E.
Published: October 2005

Power plant electrical equipment noise has been of concern from the earliest days of central plant construction, primarily because of the annoyance, disturbance and speech interference which the noise produced. Today, the concerns and efforts to reduce the noise of transformers, switchgear, motors and generator sets are largely spurred by governmental regulations. A review of past noise control work indicates that significant reductions in noise level have been achieved at the same time that equipment unit capacities have increased substantially. The state-of-the-art in measurement standards and noise control technology is reviewed and present limitations to further progress are noted. This review leads to a critical examination of the outlook for future reductions in noise levels and the likelihood of additional governmental regulations.
Noise control and the consultant in the power industry
Authors: Hoover Robert M.
Published: October 2005

Acoustics and noise control has received considerable attention in the various segments of the power industry. In fact, the power industry has contributed significantly to the development of noise control technology. However, as in other industries, the challenge is to bring the right knowledge to bear on the problem at the right time. This communication challenge and the role of the acoustical consultant serving the power industry is discussed.
In situ measurement of noise of induced-draft fans in a power plant stack
Authors: Thompson A. R. , Theobald M. A. , Simich Alex
Published: October 2005

Induced-draft fans are commonly the most annoying sources of community noise associated with fossil-fuel power plants. The low frequency tones generated by the fans are usually radiated to the community from the top of a tall stack. Measurements of the tone levels in the community are hampered by environmental effects such as strong wind and thermal gradients. Measurements within the flue gas ducting are therefore desirable. However, the flue gas environment is hostile to microphones due to elevated temperatures, particulates, and the presence of gas flow. The interpretation of in-duct data is complicated by the possible effects of standing waves and cross modes in the duct and turbulence generated noise. The recent installation of a dissipative-reactive muffler in a coal-fired plant offered the opportunity to (1) investigate techniques for measuring noise in stacks, (2) evaluate the performance of the muffler under operating conditions, and (3) check the in-stack results against limited farfield data. Good agreement was obtained between reductions in tone levels measured in the stack and in the community.
Noise impact evaluation of a power generating station and a refuse-derived fuel facility
Authors: Lee V. M. , Knoll W. L.
Published: October 2005

Community noise impact assessment of a planned addition of refuse-derived fuel (RDF) facility adjacent to a fossil-fueled power plant was conducted using a computerized atmospheric sound propagation model. Close-in measurements of power plant operation and coal handling system were used for station input, and specifications of major equipment of the RDF facility and estimated refuse-delivering trucks along plant access road segment were used for RDF noise source inputs. Site prevailing meteorological conditions for winter and summer seasons, and daytime and nighttime periods were used to account for the significant effects of the atmosphere on sound propagation. Topographical inputs of receptor grid such as bearing, ground cover, natural and manmade barriers were input from USGS topographical map. Receptor grid output corresponding to each noise source, each season and time period are computed in octave frequency bands, and A-weighted sound-pressure levels for each source or combinations of sources are presented in the form of scaled contour maps of 2 dB increment overlaying an aerial photograph of the site of the same scale. Land use and population-weighted impact can thus be easily evaluated for the existing and the future noise environment when the RDF facility comes on line. Close agreements were obtained between predicted levels of the existing power plant operation and measured levels, and excess attenuations provided by meteorology and topography contributed to the significant reduction of noise levels in the residential community.
Pile driver noise control—costs and benefits
Authors: Kessler F. M. , Schomer P. D.
Published: October 2005

The results of a Construction Engineering Research Laboratory project sponsored by EPA's Office of Noise Abatement and Control is reported here. The costs for feasible pile driver noise control methods were investigated. Noise control methods studied were: (1) substitution of a vibratory pile driver, (2) substitution of a pneumatic cushioned unit (Chelminski), and (3) silencing of a standard unit. Average costs for substituted units are as much as 110% higher than the cost of standard units, while the cost for a retrofitted silenced unit increases only 20%. Maximum pile driver sound levels are reduced about 29 dB by use of the substitute unit, and about 18 dB using a retrofitted silenced unit. The reduction in construction site one-hour equivalent sound level Leq (1), for either a substitute unit, or the retrofitted unit is only 11 dB. Thus, if only pile driver noise control is being considered, outfitting a standard unit with a well-designed muffler and enclosure is the most cost-beneficial approach for construction site noise reduction. A cost-benefit demonstration is to take place at a Corps of Engineers flood control project in Iowa. The resulting field data will be presented, if available.
Principles and history of the acoustic-suspension (air-suspension) loudspeaker system
Authors: Villchur E.
Published: October 2005

In the early 1950's loudspeakers were designed with relatively stiff mechanical suspensions. When these speakers were used as direct radiators the enclosure was made as large as possible, in order to prevent its acoustic stiffness from raising the speaker's fundamental resonance frequency. In the acoustic-suspension speaker system the quantitative relationship between mechanical and acoustic stiffness is interchanged. The mechanical suspensions are made many times more compliant, and the cushion of air enclosed behind the cone correspondingly stiffer. This air is no longer treated as a necessary evil, but as an integral design element of the system: A linear acoustic stiffness is substituted for the nonlinear mechanical stiffness of the cone suspensions. The result is a substantial reduction in low-frequency harmonic distortion, particularly in the stiffness-controlled frequency region below resonance. The enclosure size, also reduced, is dictated by the acoustic stiffness required for a predetermined resonance frequency of the mounted speaker. A brief history of the acoustic-suspension system will be presented, including published attacks on it and discussion of a patent suit in 1962.
Ultrasonic attenuation in beryllium oxide
Authors: Hickernell Fred S.
Published: October 2005

The room-temperature attenuation of longitudinal acoustic waves propagating in the c direction in single crystal beryllium oxide (BeO) has been measured from 0.3 to 1.2 GHz. The attenuation follows a frequency squared dependence with a measured attenuation of 1.1 dB/cm at 1.0 GHz. The magnitude and frequency dependence of the loss indicate an intrinsic interaction with thermally excited phonons characteristic of the ωτ ≪ 1 region. The loss level compares favorably with a value of 1.4 dB/cm predicted from thermal conductivity and crystal structure considerations [D. W. Oliver and G. A. Slack, J. Appl. Phys. 37, 1542–1548 (1966)]. Using the WE lattice loss theory [T. O. Woodruff and H. Ehrenreich, Phys. Rev. 123, 1553–1559 (1961)] a Grunheisen γ of 0.54 is calculated. This compares to longitudinal mode c-axis Grunheisen constants of 0.78 for zinc oxide and 1.51 for cadmium sulfide, binary compounds of the same crystal class. Empirical relationships were developed between crystal constants and ultrasonic attenuation for the II–VI compound hexagonal crystal class.
Gruneisen parameters of some cubic crystals using third-order elastic constants
Authors: Prasad O. H. , Suryanarayana M.
Published: October 2005

The third-order elastic constants of 26 cubic crystals and two mixed crystals belonging to octahedral class have been evaluated from the available literature data on the hydrostatic pressure variation of the corresponding second-order constants using the method elaborated [O. H. Prasad and M. Suryanarayana Acustica 38, 192–193 (1977)] wherein the third-order constants can be evaluated without any reference to uniaxial stress measurements. The evaluated third-order constants for each of the crystals are used in the well-known equations [W. P. Mason and T. B. Bateman, J. Acoust. Soc. Am. 36, 644–652 (1964)] to obtain the 39 mode gammas all of which add up to give the Gruneisen parameter γ of the crystal in question. The correctness of the evaluated parameters is verified by evaluating the thermal expansivity α of each crystal using the familiar equation connecting α with γ The crystals studied are NaCl, NaBr, NaF, LiF, KCl, KBr, KI, KF, RbCl, RbBr, RbI, AgCl, AgBr, MgO, CsBr, Nb, Fe-α, Ag, Cu, Au, Al, Ge, Si, ZnSe, ZnTe, RbAg4I5, and mixed crystals AgCl-AgBr and KCl-KBr near room temperature and in a few cases at different temperatures and pressures.
Transversal waves velocity evaluation in sand bottoms
Authors: Carbó R.
Published: October 2005

This paper presents the evaluation of the transversal wave sound propagation velocity in a wet mixture of sand, when the grazing angle is lower than the limit. This evaluation is made by means of getting the frequencies at which the amplitude of reflected echo reaches a minimum. We started from the theoretical model giving the plane waves reflection characteristics when the target is made of a series of dioptrics; in our study the dioptric was formed by two parallel perpex wall, 0.01 m thick, making a receptacle filled with the sand-water mixture of thickness several times greater than 0.01 m; this special container was then immersed in a water tank. It was possible for us to separate very clearly all the minima of the reflection coefficient corresponding to the perpex walls from those produced by the sand-water mixture, as well as to locate all the series of minima in function of the acoustic impedance presented by the mixture. By comparing these results with those obtained by straight measure of the delayed time suffered by the transversal wave traveling through the sandy layer, we are able to confirm the behavior of the sand medium, for transversal waves propagation, in function of porosity.
A technique for measuring the complex acoustic ground impedance
Authors: Myles Mark M. , Willshire William L.
Published: October 2005

The goal of the study described in this paper was to demonstrate the use of an impulsive source and a Fast Fourier Transform (FFT) processor in an efficient and precise measurement of the complex ground impedance. In essence, this technique measures the impulse response of a sound propagation path that includes a reflection from the ground surface of interest. By simultaneously measuring both the input and output of the system (i.e., the “direct” wave and “reflected” wave) and Fourier transforming them, the Transfer Function can be evaluated. This Transfer Function is identically equal to the complex reflection factor, from which the complex impedance can be derived. Because of the difficulties reported in the past in obtaining the phase of the ground impedance, particular attention was paid to obtaining valid complex results. [This work supported by NASA Langley Research Center.]
Cavitation thresholds of polyalkalene glycol and of castor oil
Authors: Moffett Mark B.
Published: October 2005

Measurements were made of the cavitation threshold for polypropylene glycol and for castor oil in a cylindrical resonator at approximately 16.5 kHz. The threshold for degassed castor oil was ∼233 dB//iμPa peak, in agreement with the measurements of Briggs, Johnson, and Mason [J. Acoust. Soc. Am. 19, 661–664 (1947)]. Degassed polypropylene glycol exhibited wide variability in threshold, with an initial value ∼240 dB//1μPa peak, dropping quickly to values ∼225–228 dB//1μPa peak. Partial restoration to higher values could be attained after a five-hour rest period. [Work supported by Naval Sea Systems Command.]
Sound radiation efficiency of metals
Authors: Dreiman N. I.
Published: October 2005

The purpose of this investigation was to determine the influence of controllable metallurgical properties on the radiated sound after impact using iron—manganese alloys and some forge hammer construction metals. The effect of metal properties on sound radiation can be characterized by the rate of attenuation of the sound, dp. For rectangular plate linear dimensions a and b. dp = 60[(ma)2 + (nb)2]Q−1(σ0Eh3rs)1/2 × {4.8498[σ0(1 − μ2)mprs]1/2 − 0.3536[(ma)2 + (nb)2] × Q−1(πEh3ms)1/2}−1 + C, dB/s, where E is elastic modulus, μ is Poisson's ratio, Q−1 is internal friction, σ0 is ultimate strength, p is the mass density, m, n is a mode number, h is the thickness of the plate, rs is the radius of the striker, ms is the mass of the striker. C is a constant accounting for the changes due to environmental scattering and absorption by the surfaces. The attenuation rate of sound radiation has been shown to be affected by the mechanical properties of the metal and geometry of solid collision. The mechanical properties can be modified by controlling the heat-treatment and the chemical composition of the metal, as well as its mechanical working.
Experimental vibration study of fluid coupled coaxial flexible cylinders
Authors: Chu M. L. , Brown S. J.
Published: October 2005

This study is an attempt to simulate the vibration of a breeder reactor vessel with a “thermal shield.” The model cylinders were made of acrylic with different diameters and thicknesses. Parameter study was performed by a series of different combinations of outer and inner cylinders. The cylinders with fluid (H2O) in the annular gap were mounted concentrically to a massive vibrating stand and point excited by a shaker. The natural frequencies and mode shapes were obtained using two “mapping” eddy current probes. Damping ratios were computed using the standard “half-power” technique. Two distinct responses were observed in the relative radial displacement between inner and outer cylinders, i.e., (1) in-phase, and (2) out-of-phase.. In the out-of-phase modes the natural frequency of the system is found to decrease to either zero or a limiting low value as the gap size decreases, whereas in the in-phase modes, the opposite occurs. In both cases the frequency varies nonlinearly with the gap size. In both the in-phase and out-of-phase modes the frequency decreases as the thickness of the inner cylinder decreased. The damping ratios are found to increase as the gap size decreases, from 5% to about 15% for flexible outer and inner cylinders, and from 4 percent to about 32% for a flexible inner cylinder and rigid outer cylinder combination. [Support by B and W is acknowledged.]
Effects of middle-ear muscle contraction on transmission of sound to the inner ear (cat): Some direct measurements
Authors: Nedzelnitsky Vicior
Published: October 2005

Measurement of sound pressure in scala vestibuli was used to examine the effects of middle-ear muscle contraction on transmission of tone bursts so intense (e.g., 80 to 140 dB SPL at the tympanic membrane) that conventional techniques using cochlear electric potentials are inapplicable. The muscles were stimulated electrically in order to elicit stable, well-controlled muscular contractions. Stapedius contraction appears to dominate the measured effects on transmission, although a contribution from the tensor tympani is not excluded. Stimulating electrode locations and stimulus levels were adjusted to produce displacement amplitudes of stapedius contraction within the range measured by direct optical observation of acoustically elicited stapedius contraction in decerebrate preparations. The electrically induced contractions attenuated tone bursts by as much as 35 dB at 500 Hz and 20 dB at 6000 Hz. The effect was approximately linear in that tone bursts of differing amplitudes received essentially the same attenuation for a given level of muscular contraction. [Work supported in part by NIH and the Research Fund of the American Otological Society. Decerebrate surgical preparation of cat developed by J. J. Guinan and E. M. Marr.]
The effect of age on stapedius reflex growth function in normal and pathological ears
Authors: Silman S. , Gelfand S. A.
Published: October 2005

The effect of age upon the acoustic stapedius reflex growth function was studied in 14 normal ears and 16 ears with sensorineural loss of cochlear origin. [t was found that reflex magnitude was significantly correlated with static acoustic impedance. Reflex magnitudes were therefore expressed in dB re: static impedence, since the results would have been misinterpreted if they were plotted in terms of absolute impedance change. When plotted relative to the reflex threshold, the growth functions of both groups were similar for tonal and white noise activating signals. When plotted relative to activator SPL, the growth functions of the hearing loss group were displaced by an amount consistent with the elevation of the reflex threshold. Further, the linear portion of the normal growth function and the entire growth functions of the hearing loss group were essentially parallel. However, the normal growth functions became curvilinear at high activator levels due to saturation, whereas this did not occur for the hearing loss group. This indicates that saturation was not yet reached by the ears in the hearing loss group, which continued to integrate additional energy linearly at levels above the saturation point of the normals. This suggests that the acoustic reflex is energy based. [Supported by Veterans Administration.]
Low level acoustic reflex thresholds
Authors: Blood I. M. , Greenberg H. J.
Published: October 2005

The acoustic reflex threshold (ART) can be detected at lower than normal sound pressure levels by means of facilitation. This procedure entails simultaneous presentation of a high frequency tone at a level just below the ART and a threshold seeking stimulus. The threshold seeking stimulus is presented in decrements until no further reflex activity can be observed. Difference values between normal and reduced ARTs were obtained from 18 normal hearing and 18 sensorineural hearing-impaired ears. Each subject was exposed to twelve conditions: threshold seeking signals of pure tones or octave bands of noise were presented in conjunction with a 4000 Hz facilitating tone in either the same ear (monotic mode) or in opposite ears (dichotic mode). Threshold shifts were significantly greater for the normal hearing subjects than for the hearing-impaired subjects. In the hearing-impaired ears, the facilitated ART produced a lesser degree of threshold reduction or no apparent threshold shift. For the normal hearing ears, the monotic mode of signal presentation produced greater threshold shifts than the dichotic mode.
The optimization of constrained layer damping applications
Authors: Miles R. N.
Published: October 2005

It is well known that the attachment of a stiff elastic (constraining) layer to a beam by using a viscoelastic damping adhesive can be a highly weight efficient means of reducing the beam's resonant response if this damping treatment is carefully designed. Though the prediction of the damping effectiveness of constrained layer damping treatments has been well understood for over twenty years, their optimum design is often obtained by trial and error. To avoid this, an efficient method is presented for optimizing the adhesive layer's thickness. This is usually the most difficult parameter to optimize and existing design guidelines are not always accurate. It is shown that if the ratio of the “effective” shear stiffness of the adhesive layer to the “effective” extensional stiffness of the metal layers is greater than a factor that depends only on the adhesive's loss tangent, the damping effectiveness will increase monotonically with increasing adhesive layer thickness. If the ratio is less than this factor there will be some optimum value of adhesive layer thickness. The value of this thickness is obtained by a simple numerical procedure.
The transients of a multiresonant vibrator
Authors: Skudrzyk E. J.
Published: October 2005

When a periodic force is applied to a complex vibrator, the motion builds up exponentially in much the same manner as that of a point-mass compliant-element vibrator. But, in addition, a transient is generated that resembles very much the switching-on transient of a high-pass filter. It consists of a spike followed by a rapidly decaying sinusoidal vibration of a frequency equal to the cutoff frequency of the filter, which is practically equal to the forcing frequency. If the forcing frequency is close to a resonance frequency, a decaying component of this frequency may also appear in the result. At an antiresonance frequency of the vibrator, the modal contributions counteract each other and the resultant steady-state amplitude is very small. But, the transient components have different frequencies and do not cancel each other. They generate a beat phenomenon of considerable amplitude with a carrier frequency that is practically equal to the forcing frequency. The transients at the beginning and at the end of a pulse of a transducer that need to be used in a wide frequency range are, therefore, just as useful for measurements with sinusoidal tone bursts as the steady-state sound between them. Theory and experimental results will be presented. [Work supported by ONR, code 474.]
Phonograph pickups as low-cost vibration transducers
Authors: Powell Robert E. , Busch-Vishniac Ilene
Published: October 2005

Velocity-sensitive phonograph cartridges can be very useful for vibration measurements on light structures where accelerometers present too much mass loading. This paper describes how stereo phonocartridges may be calibrated and used to measure in-plane (horizontal) and also transverse (vertical) motion. Topics of discussion include frequency response, dynamic range, proper mounting methods, and calculation of the effect of the stylus impedance on vibration of beams and plates. Data from measurements on several different structures is included.
The perception of speech in an unfamiliar language
Authors: Rudnicky A. I.
Published: October 2005

Experiments in speech perception almost invariably use speech tokens and response categories drawn from the language native to the listeners participating in the experiments. This has served to confound the listeners' extensive knowledge of their own language with their ability to perceive speech stimuli as such. The present study attempts to separate these two components of speech perception. Short (4–5 s) excerpts of English and non-English speech were altered in one of two ways: by the deletion of a closure silence or by the addition of a 100 ms silence to an existing closure silence. Native English listeners were highly adept at detecting and identifying alterations in English. However, their performance was at a chance level on non-English excerpts. The original foreign talkers also listened to the excerpts: they performed well with excerpts of their own language and poorly in all other languages. These experiments underline the importance of experience in speech perception and suggest that the perception of even elementary speech events may depend on the listener's familiarity with the context in which they occur.
Boundaries in the perception of continuous speech
Authors: Martin J. G.
Published: October 2005

There were 48 “sentences” (e.g., “LAS a BAS a LAS, a GAS a LAS a PAS” or “KAS a LAS a PAS, a LAS a BAS a LAS”) each pronounced with a slight phraselike boundary after the fifth syllable. Four groups of practiced subjects pressed a reaction-time (RT) button to their assigned segmental target /b, d, g, or k/ which occurred equally often in syllables one, three, five (first phrase), seven, nine or eleven (second phrase). The decrease in target RT as a function of time into the sentence was not monotonic. Instead, target RT decreased successively within the first phrase, but increased after the boundary before decreasing again within the second phrase. This “scallop” effect suggests a relative discontinuity across boundaries in both production and perception. Phrases are units in the sense that articulatory-acoustic sequential redundancy (correlation) is higher within that between phrases. In perception, such redundancy facilitates increased ease in “tracking” the successive syllables in a phrase until the boundary is reached. [Work supported by NIH.]
Speech evoked potentials in response to grammatical structures
Authors: Clardy S. Mark , Hayden Mary Ellen , Singh Sadanand , Reilly Edward L.
Published: October 2005

The purpose of the present study was to monitor the electrophysiological responses to phrases varying in degree of grammaticality, congruity, and markedness. Eight English phrases were synthetically produced to control duration, amplitude, and alignment. These were composed of “I,” “She,” “A,” or “Three” followed by the nonsense word “wug” or its morphophonemically marked counterpart “wugs.” Cortical evoked potentials were monitored from F7, F8, and midway between Ta and P3, and midway between T4 and Px (International 10–20 Systems of the Electrode Placement), each referenced to the ipsilateral earlobe. Ten male, right-handed subjects between the ages of 20–30 years were solicited from among The University of Texas Health Science Center at Houston faculty and students. Ss were told to listen with eyes closed and to avoid movement. Evoked responses were averaged over 64 randomly ordered presentations of each stimulus, thus yielding a total of 512 presentations per S. Preliminary analysis indicates that the AEPs on the right were similar regardless of grammatical complexity, congruity, or markedness. AEPs on the left, however, were more variable depending on grammatical factors.
Perceptual synthesis of deleted phonemes
Authors: Bashford James A. , Warren Richard M.
Published: October 2005

Addition of noise to gaps produced by deletion of speech segments has been reported to result in both illusory continuity and increased intelligibility. Earlier work in this lab involving phonemic restorations within single noise filled gaps in sentences has suggested that such multiple perceptual restorations may represent a linguistic adaptation of a nonverbal phenomenon. “Temporal induction” permits perceptual synthesis of contextually appropriate sounds when deleted segments of a signal are replaced by noise with intensity and spectral characteristics capable of masking the signal were it really present in the noise. A series of experiments used broadband and filtered speech consisting of PB word lists, CID sentence lists, and speech passages. Periodic interpolated noise bursts were varied in spectral composition, and it was found that illusory restoration of continuity followed the spectral rules for nonverbal temporal induction. While illusory speech continuity of word lists could occur without an increase in intelligibility, illusory continuity of connected speech improved intelligibility through restoration of contextually appropriate phonemes. Temporal induction becomes coupled with special linguistic mechanisms permitting perceptual synthesis of phonemes from noise when sufficient contextual information is available.
Identification and discrimination of a new linguistic contrast
Authors: Aslin R. N. , Pisoni D. B. , Hennessy B. L. , Perey A. J.
Published: October 2005

For many years there has been a consensus among investigators that the linguistic experience of an individual exerts a profound and quite often permanent effect on the perceptual abilities required to identify and discriminate speech sounds. Based on the results of a small number of studies, it has been further assumed that selective modification of phonetic perception cannot be accomplished easily and quickly in the laboratory with simple discrimination training techniques involving only a few hours of practice. These findings have been interpreted as support for the notion that the underlying neural mechanisms become so finely aligned by the linguistic environment that they can no longer be modified or “returned” in adults. In the present paper we report the results of three experiments that systematically examined the acquisition of a new linguistic contrast in voicing. Laboratory training procedures were implemented with a small computer in a real-time environment to establish a three-way contrast among voiced, voiceless unaspirated, and voiceless aspirated stops. New perceptual categories emerged quite rapidly for most monolingual English subjects after only a few minutes and subsequent perceptual tests revealed reliable and consistent labeling and discrimination functions for all three categories. These new results differ quite substantially from all previous studies in demonstrating that the adult perceptual system is, in fact, quite plastic and can be modified selectively by environmental input. [Supported by NIMH and NINCDS.]
Identification of temporal order in vowel sequences
Authors: Kerivan J. E. , Alfonso P. J. , Bornstein S. P.
Published: October 2005

The effects of element speed and element pitch contour were studied for synthetic vowels /i, æ, a, u/ in various permuted sequences. Four trained subjects were asked to identify temporal order in this closed response vowel set. A high-level stimulus uncertainty procedure was used. Subjects were near perfect performance at element durations ranging from 90–150 ms. They were above d′ = 1.0 level at 30 ms per element and d′ = 2.0 at 60 ms per element. Performance on individual sequence permutations varied little at 90–150 ms per element but varied between chance and slightly above d′ = 2.0 at both 30 and 60 ms per element. The effect of normalizing element pitch contours was negligible for individual sequence permutations at all element speeds. The duration threshold of vowel sequence identifiability (125–200 ms per element) reported by other investigators using a recycling presentation format is considerably longer than these 30–60 ms per element thresholds. A more sensitive approach to determine absolute duration thresholds for vowel sequences appears to be with trained subjects using a single sequence versus a recycling sequence method.
Discrimination of intraphonemic differences along two place of articulation continua
Authors: Edman Thomas R.
Published: October 2005

Discrimination of intraphonemic differences along two place of articulation continua is examined in a transfer of training experiment. Initial psychometric functions were obtained from six subjects on /bae-dae-gae/ and /pae-tae-kae/ series. Half the subjects then received discrimination training on the voiced series and the other half received discrimination training on the voiceless series. Finally, post-training psychometric functions were obtained from all subjects on both series. All subjects show low levels of intraphonemic discrimination on both series before training, and high final levels of intraphonemic discrimination for the series on which they were trained. Additionally, most subjects show high final levels of discrimination on the nontraining series. Implications of these results are discussed.
Coarticulation and the identification of initial and final plosives
Authors: Pols Louis C. W.
Published: October 2005

Natural CVt and tVC utterances (V = |i,u,α|; C = |p,t,k,b,d,g|) of one American English male speaker were used to evaluate which information in CV and VC syllables is perceptually relevant for the identification of initial and final plosives. Different initial or final parts of the utterances were deleted and replaced by silence or by a 300-ms burst of noise. Subjects were asked to identify the (deleted) plosives. The noise paradigm was introduced to make the incomplete (C)Vt or tV(C) syllables sound more natural: it improved the correct score for initial plosives. Identification results are interpreted in articulatory and spectral terms. For initial unvoiced plosives most coarticulation takes place in the aspiration part and hardly any information about the preceding plosive is preserved in the vowel (transition) part. For the heavily truncated (C)ut stimuli, subjects give mainly |b| responses, while |p| is the favorable response for all heavily truncated tV(C) stimuli. [Research carried out at Speech Communications Research Laboratory, Inc., Santa Barbara and supported by the Netherlands Organization for the Advancement of Pure Research (ZWO).]
The effects of number of repetitions and intensity level of adaptors varying in VOT on verbal transformations
Authors: Ohde Ralph N. , Sharf Donald J.
Published: October 2005

The purpose of this study was to investigate the effects of number of repetitions and intensity level of adaptors varying in VOT on verbal transformations. Fifteen subjects rated the 5-, 25-, and 55-ms VOT adaptors periodically during periods of repetitions so that transformations could be identified according to their place and voicing characteristics. The number of adaptor repetitions was 5, 32, or 95 and the intensity of the adapting stimulus was 50, 70, or 90 dB SPL. The major findings were as follows: (I) A significant difference in number of verbal transformations was obtained between each repetition condition for the 55-ms adaptor but only between the 5 and the 32 and 95 repetitions conditions for the 5- and 25-ms adaptors; (2) The 90-dB level produced significantly more verbal transformations than either the 50 o or 70-dB levels for the 55-ms adaptor only; and (3) The proclivity for stop + vowel transformations over other syllables and nonspeech transformations was greater for the 5- and 25-ms adaptors (72% vs 28%, respectively, and 84% vs 16%, respectively) than for the 55-ms adaptor (58% vs 42%, respectively). The findings will be discussed relative to verbal transformation and adaptation models and to asymmetries in the perception of voicing. [Work supported by Sigma Xi, Harlan Bloomer Fund and NIH research grant NS07040.]
Measuring phoneme boundaries four ways
Authors: Ganong W. F. , Zatorre R. J.
Published: October 2005

In order to determine whether the concept of “phoneme boundary” has any validity independent of a particular experimental paradigm, four procedures were used to locate the boundary on two different acoustic continua: a VOT continuum. ranging from [ba] to [pha], and a formant transition continuum, ranging from [bæ] to [dæ]. One procedure consisted of a standard identification test (boundaries were later determined by regression). The PEST procedure determined the position of the phoneme boundary adaptively. In the up/down procedure, subjects simply indicated when ascending or descending series of stimuli crossed the boundary. In the fourth procedure, subjects adjusted the stimulus presented until it fell on the boundary. The procedures differed in reliability, and there were substantial individual differences in the locations of the phoneme boundaries, but the correlation between boundary locations for each subject found by the different procedures was quite high. This result suggests that, despite recent suggestions that phonetic categorization is susceptible to cognitive biases, phoneme boundaries do exist independent of the particular methods used to measure them. [Work supported by NSF, NIMH, NICHD.]
Temporal organization of auditory and phonetic analyses in speech discrimination
Authors: Miller C. J. , Feth L. L. , Daniloff R. G.
Published: October 2005

Speech discrimination was investigated in four reaction-time (RT) experiments using synthetic three-formant CV's. Listeners heard syllable pairs which were either identical, or differed by 20 ms along the voice-onset-time continuum from /bi/ to /pi/, and made SAME/DIFFERENT judgements. Discrimination pairs were selected to enhance absolute (auditory) decision strategies in one task, while classification (phonetic) strategies were similarly enhanced in a second. Optimum performance in two additional tasks required combinations of both strategy types. One of the latter served as a base-line condition, being similar to that for categorical perception studies. In all conditions except the base-line, on-line feedback was used to maximize performance. Serial process models for speech perception would predict systematic differences among response latencies in the four tasks. Since such differences were not apparent in the RT data, results suggest auditory and phonetic analyses are concurrent in speech discrimination. [Work supported in part by NIH.]
The identification of some voice qualities
Authors: Estill J. , Colton R. H.
Published: October 2005

The perceptual distinctiveness of four common voice qualities was assessed by asking observers to place the stimuli produced in the four voice qualities, at five different fundamental frequencies by five subjects into one of four unnamed perceptual categories. The qualities tested were that heard (1) in most everday speech, (2) during a low-level whimper or cry, (3) in country-western singing, and (4) in most singing on the operatic stage. All voice qualities were correctly categorized above chance level at all frequency levels. Analysis of the perceptual confusions was conducted using an information theory approach. The results of this analysis suggests that some of these vocal qualities share some common perceptual features and that each quality may be thought of as a set of distinctive perceptual features.
Cerebral dominance for conspecific sound perception in monkeys?
Authors: Petersen Michael R.
Published: October 2005

Convergent evidence from electrophysiological, anatomical, and behavioral studies suggests a preeminent role for specific regions of the human left cerebral hemisphere in both the production and perception of speech sounds. The present study aimed to determine whether nonhuman primates show a similar lateralization of function when performing perceptual tasks requiring the analysis of species-specific vocalizations. Five Japanese macaques (Macaca fuscata) and five other Old World monkeys were trained, using operant conditioning techniques, to discriminate between different classes of acoustic stimuli. In one experiment, all animals were required to discriminate between two classes of Japanese macaque vocalizations by attending to a communicatively significant acoustic cue. In a second experiment, the animals were forced to attend to an orthogonal acoustic feature of the same vocalizations. In both experiments, stimuli were delivered monaurally to either the left or right ear according to a random schedule. All five Japanese macaques but only one of the comparison animals showed a right-ear performance advantage, suggesting left hemisphere dominance, when analyzing the communicatively significant feature of the vocalizations. Neither the Japanese or comparison animals showed a right-ear advantage when processing the orthogonal pitch feature. The results directly parallel studies of human speech lateralization which report a right-ear advantage for the processing of linguistically relevant acoustic cues but not for the perception of paralinguistic cues. Therefore, our findings suggest a potential analogy between the functionally lateralized mechanisms used in human speech and those apparently engaged by the Japanese macaques for the analysis of conspecific sounds. [Work supported by NSF, NIH and NIMH.]
Total-energy principle incorrect for twice-weekly exposures
Authors: Ward W. D. , Kiester T. , Turner C. W.
Published: October 2005

Groups of four chinchillas were exposed to 700–2800-Hz noise: group A for 220 rain at 114 dB SPL, group B for 220 min at 111 dB SPL, and group C 22 times (twice a week for eleven weeks) for 10 min at 114 dB. Permanent threshold shifts (PTSs) and cochlear damage in group C were smaller than in either of the other two groups, although the total-energy theory of auditory damage would predict that group C should show the same effects as group A and more than group B. In fact, group C displayed the effects that would be produced by a 220-min exposure at 108 or 109 dB, indicating that in this particular case, the effective dose was 5 or 6 dB less than the actual dose. Curiously, the greatest PTS produced by the 22 10-min exposures occurred at 250 and 500 Hz, thus providing an intriguing complement to the production of high-frequency losses by low-frequency stimulation. The relation of PTS and cochlear damage to the temporary threshold shift 1 h after exposure (TTS60) will be discussed; in general, full recovery occurs frequently following a TTS60 of 50 dB, sometimes after a TTS60 of 60 dB, rarely after a 70-dB TTS60, and never after a TTS60 of 80 dB or higher. [Work supported by USA taxpayers through NIH grant NS12125.]
Temporary threshold shifts produced by 24-h exposures to intermittent noise
Authors: Mills J. H. , Gilbert R. M. , Adkins W. Y. , Kulish L.
Published: October 2005

Human subjects (N = 106) were exposed in a diffuse sound field for 24 h to a wide-band noise with an A-weighted sound level of 92.5 dB. The noise was intermittent with on times of 1. 10, 100, 1000 or 10 000 s. Duty-cycle was 50%, 75%, or 90%. During an exposure, the subject was removed from the noise, temporary threshold shifts were measured, and the subject was returned to the noise. Regardless of the on-time or duty-cycle TTSs increased for about 8-12 h, and measurements of TTS after 24 h of exposure were nearly identical with those measured after 8 h. The magnitude of TTS was related in a complicated manner to on-time and duty-cycle. For on-times greater than about 4000 s (≈66 min) the magnitude of TTS approached or equaled the TTS produced by a steady-state exposure. For on times less than about 1000 s but greater than 10 s, TTS is directly related to duty cycle. For on-times of 1 s or less and duty-cycles greater than 50%, TTS appears to approach the TTS produced by a steady-state exposure. [Work supported by NIEHS.]
The influence of whole body vibration on asymptotic threshold shift induced by impulse noise
Authors: Henderson D. , Hamernik R. P. , Coling D.
Published: October 2005

Whole body vibration can alter the susceptibility of the chinchilla cochlea to noise induced hearing loss. Five monaural chinchillas were exposed to a combination of 1 g rms, 30 Hz wholebody vibration and impulse noise at 113 dB SPL, 1/s for 10 days. Thresholds were monitored using the AER technique before, during and after the exposure. Surface preparation histology was obtained from each animal. Whole body vibration did not appreciably affect the ATS levels (30 dB at 0.5 kHz and 40 dB at 8 kHz) but the PTS levels (20 dB at 0.5 kHz; 24 dB at 8 kHz) were significantly higher than in the noise alone control animals. Histologically, the combination animals had a distribution of hair cell loss similar to that of the noise alone animals, but significantly more outer and inner hair cells were missing. The stria vascularis was also severely damaged in some animals. Correlations between hearing levels, and histology will be presented. [Work supported by NIEHS.]