bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of age on hearing in rats
Authors: Turnock M. T. , Harrison J. M.
Published: October 2005

The effects of age on behavioral aspects of hearing is currently being studied. The tracking method is being used in a longitudinal study measuring absolute auditory thresholds for narrow noise bands with varying center frequencies. Tests are conducted at each frequency with three-month intervals separating each test. Data are presented for two animals. The younger animal (4–14 months) shows no uniform change over time for any of the frequencies. The thresholds of the older animal (30–39 months during the present study) show a loss over previously measured thresholds presented in an earlier paper [J.M. Harrison and M.T. Turnock, J. Exp. Anal. Behav. 23, 141–147 (1975)] when the animal was 24 months old. Subsequent measures show a progressive hearing loss over time of approximately 7 dB for the high and low frequencies, and 11 dB for center frequencies. A second study examines acquisitional and asymptotic behavior of a discrimination of speaker position, using pure tones of varying rise-decay times presented either singly or in bursts. There were no significant differences in behavior of young (2–6 months), middle (10–14 months), or old (27–31 months) rats, except for a slightly more pronounced acquisition curve for the young animal. The data are discussed in terms of previous behavioral and anatomical studies examining the effects of age on hearing.
Latency and amplitude functions in brain stem response (BSR) audiometry
Authors: Davis H. , Hirsh S. K.
Published: October 2005

In electric response audiometry the vertex-positive wave with latency of about 6 msec (P6), originating in the brain stem (BSR), is a sensitive and reliable indicator. It is closely related to the first response (N1) of the auditory nerve: the latency difference is constant at about 4.0 msec. As in the electrocochleogram, BSR shows both a low-intensity and a high-intensity branch in its latency-intensity and its amplitude-intensity functions, with changes of slope, breaks, or plateaus in the range from 40 to 60 dB SL. Thus brain stem audiometry, like electrocochleography, can show a “recruitment-type response” (absence of the low-intensity segment) in certain types of cochlear pathology. [Work supported by NINCDS.]
Selective attention and simple auditory recognition: Methodological considerations
Authors: Ahroon W. A.
Published: October 2005

We have reported at recent meetings a severe performance decrement in two-channel frequency difference limen tasks. In these studies, d's in both the selective attention and divided attention conditions were significantly depressed relative to monaural levels. When the signals to the two earphone channels were widely separated in frequency (by nine to ten critical bands), the selective attention condition was improved relative to the divided attention condition, yet still significantly below monaural performance levels. When all signals were within the same critical band (or were separated by only two or three critical bands), there were no significant differences between the two dichotic conditions. The present study generated psychometric functions under the selective and divided attention conditions for signals within the same critical band. Using this procedure, differences between the two dichotic listening conditions are evident in both absolute performance levels and in the psychometric functions. The results of the present experiment clearly indicate the need for greater use of adaptive psychophysical methods in the study of dual channel listening. [Research supported by grant NS 10995 from N.I.N.D.S.]
Lateral position and interaural discrimination: Data and blackbox model
Authors: Domnitz R. H.
Published: October 2005

Experimental results are described for the dependence on interaural stimulus parameters of subjective lateral position and just-noticeable differences in interaural amplitude and time. The experiments employed 500-Hz tones presented through acoustically monitored headphones [R. H. Domnitz, J. Acoust. Soc. Am. 58, 510–511 (1975)] at 55 dB SPL. The overall amplitudes of the stimuli in the interaural amplitude discrimination experiment were iteratively adjusted to eliminate subjective loudness cues. Performance in the experiments is analyzed within the framework of a probabilistic subjective lateralization model in which internal noise is explicitly treated. One prediction of the model relates the ratio of the interaural time and amplitude jnd's to subjective position. Although the data are qualitatively consistent with this prediction, there is close quantitative agreement for only one of three subjects. The model also predicts values of the internal noise of the subjective image position and these are in qualitative agreement with reports of image diffuseness as a function of interaural parameters. Nontradability between large increments of interaural amplitude and time is implied by the experimental results, and can be interpreted in the model as discrimination between tones with equal position means but different position variances. [Work supported by NIH.]
Waveform patterns of reflex and voluntary contraction of the middle ear muscles
Authors: Jeter Irma K.
Published: October 2005

Changes in impedance produced by reflex and voluntary contraction of the middle ear muscles and by Eustachian tube activity were compared among 24 normal subjects. Middle ear (ME) impedance changes were recorded graphically during the following maneuvers: (1) Eustachian tube (ET) activity produced by wet swallowing; (2) the acoustic reflex (AR); (3) orbicularis oculi contraction (OO); (4) voluntary contraction of the middle ear muscles (VCMEM). Biofeedback was used to teach subjects VCMEM. Approximately half the population successfully accomplished VCMEM, but only a few subjects could sustain VCMEM. Six different waveform patterns were identified among impedance changes. Identical waveform patterns were recorded for the AR in all subjects. A distinct difference between impedance changes resulting from ET activity and MEM activity was observed. Results indicate (1) VCMEM can be taught to some individuals using biofeedback; (2) there are distinct differences between waveform patterns produced by MEM activity and ET activity; and (3) differences exist between the type of impedance change resulting from the AR compared to those resulting from both OO and VCMEM.
Effects of the acoustic reflex on middle-ear transmission and eardrum admittance in man
Authors: Rabinowitz W. M.
Published: October 2005

Psychophysical measurements of middle-ear transmission change, 0.4 to 4 kHz, and physical measurements of eardrum acoustic admittance, 0.063 to 4 kHz, have been made on four normal-hearing subjects during activation of the acoustic reflex via contralateral noise, LN′, 80–110 dB SPL. The psychophysical data have been obtained by exploiting the sensitivity of the phase of the aural combination tone 2f1−f2 to primary tone level [W. M. Rabinowitz and J. L. Goldstein, J. Acoust. Soc. Am. 54, 293(A) (1973)]. The admittance measurements have been obtained with a specially designed electroacoustic probe tip assembly coupled to an automated transfer function analyzer. The middle-ear transmission, |H(f)|, changes monotonically with LN. For the maximal elicitor used, LN-max, the average Δ|H(f)| is −10 dB (σ = 1.8 dB) for f ⩽ 0.63 kHz, −2 dB at f = 1.25 kHz, and zero (±1 dB) for f ⩾ 2 kHz. The observed admittance change, Δ|Yd (f)|, for LN-max is −2.5 dB (σ = 1.4 dB) for f ⩽ 0.63 kHz, zero at 1 kHz, +1.5 dB at 1.25 kHz, and zero at 4 kHz. Together the Δ|H(f)| and Yd(f) data provide constraints on possible middle-ear models. [Work supported by NIH.]
Mobility/radiation factor evaluations as design aids for high performance vehicles
Authors: Douglas B. E.
Published: October 2005

The application of mechanical mobility and radiation factor methods to augment standard structure-borne and airborne noise surveys in diagnosing structural contributions to vibroacoustic deficiencies on high performance vehicles is considered. Emphasis is placed on the development of a field-oriented analysis method based on a normal mode interpretation of mobility and radiation factor measurements to characterize the dynamic response of the structural elements of such vehicles. These characteristics (i.e., natural frequencies, modal loss factors, mode shapes, relative noise transmission path strengths, modal density, termination mobilities, and acoustic radiation efficiencies) provide information which influences the selection, design, and performance of all transmission path noise control methods that are applicable to corrective redesign. The effects of modal density on such an analysis approach are briefly examined along with techniques to resolve modal information from normal modes closely spaced in the frequency domain. Applications of the methods to shipboard noise problems are presented. Mobility/radiation factor evaluations were found to provide an economical means of obtaining vibroacoustic design information for high performance vehicles where transverse modes govern the vibratory response of the vehicular shell.
Improved solutions of the two-dimensional fluid cochlea model using Green's functions
Authors: Allen I. B.
Published: October 2005

Exact numerical solutions have been found for the two-dimensional cochlea model proposed by Lesser and Berkley [J Fluid Mech. (January 1970)] using the Green's function method as first suggested by Cox and Lien. The Green's function method has proven to be stable, accurate, and faster than several other numerical techniques that have been tried. Interesting results include a sharp discontinuity in the slope of velocity spectral magnitude for frequencies above the place as observed by Rhode [J. Acoust. Soc. Am. 49, 1218 (1971)].
Fluctuating pressures in jet flows over airfoil surfaces
Authors: Haviland J. K. , Herling W. W.
Published: October 2005

Fluctuating pressures have been measured in a rectangular jet using static probes connected to 1/8-in. microphones by plastic tubing. Tests were made with the jet free and with it impinging on an airfoil, as part of an effort to predict dynamic loads and jet noise effects on STOL aircraft. Signals were processed singly with rms and 1/3-octave analyzers, as well as in pairs with a digital correlator whose output was Fourier analyzed to get spectral densities (corrected for instrumentation effects), relative amplitudes, phase angles, and coherences. Comparing pressure spectra of the rectangular jet with those of a previously analyzed circular jet, it was found that the typical single frequency peak of the latter was replaced by several peaks, the two most prominent corresponding to the rectangular dimensions of the jet. When the airfoil was present, the higher peak was repressed and an intermediate peak was accentuated. Cross-correlation and phase/coherence measurements indicated the presence of vortices aligned to the flow, as had been previously demonstrated for circular jets. [Work supported by NASA Grant No. 47-005-219.]
Resonances in folk guitars
Authors: Haines Daniel W. , Haltiwanger Mary Ann , White Timothy P.
Published: October 2005

Resonance frequencies of a series of folk guitars were determined by forced vibration and impulse tests. The locations of these resonance frequencies were found to influence strongly the characteristics of the loudness curve obtained from the instrument when played; peaks of the loudness curve occurred when the fundamental or an overtone coincided with a strong resonance of the guitar body. The two strongest, the air and the wood resonances, were typically found near G almost an octave apart. Analysis of plucked tones showed that these resonances are excited to some extent regardless of string frequencies, a source of aperiodicity in guitar tones. Preferred chords and keys seem to be related to resonance location, e.g., C, G, G7, are common chords which are strongly reinforced by resonances at G. However, the importance of resonance location should not be exaggerated for it seems that any guitar with good action will find someone to love it. [Partially supported by the NSF.]
Design and testing of a viscoelastic shear damper for an inertial guidance unit
Authors: Nelson F. C. , Sullivan D. F.
Published: October 2005

Inertial guidance units must protect sensitive instrumentation against vibration. At resonance, this protection can be increased by augmenting the system's structural damping. This paper discusses damping augmentation by means of axial shear of a ring of viscoelastic material. The paper will discuss the design of the shear damper, the selection of a suitable viscoelastic material, and test results on a simplified subsystem.
Noise exposure and auditory physiology
Authors: Tonndorf Juergen
Published: October 2005

The ear is an extremely sensitive detector of acoustic energy. Its dynamic range at 1 kHz is at least 120 dB, although some harmonic distortion occurs at 70 to 80 dB SPL. The range of sensitivity is from about 20 to 20 000 Hz, although sensitivity decreases on both sides of an 800–7000 Hz band. There is an absolute limit above which the ear is likely to suffer direct physical damage: rupture of the eardrum occurs at about 140–160 dB SPL and, more importantly, destruction of the sensory elements of the inner ear at about 140–150 dB SPL. Much below these levels, i.e., starting at about 80–90 dB SPL, the sensory elements are gradually worn out, where there is some reciprocal relationship between exposure level and duration. There are some built-in protective mechanisms, but their effectiveness at industrial noise levels is rather low. After a brief outline of the ear's anatomy, some examples of noise-damaged ear tissues obtained in experimental animals and/or accidentally found in man will be demonstrated. [Supported by several NIH grants.]
Recent developments in the effects of noise on speech communication
Authors: Pearsons K. S.
Published: October 2005

This presentation is basically a progress report of an ongoing project investigating levels of speech normally employed in everyday conversation. The main area of interest has been in homes and schools, but other environmental areas are under consideration, such as hospitals, shopping areas, and inside transportation vehicles. In addition to the speech levels, measures of the background noise are also obtained and used along with the speech levels to determine Articulation Index. We thus have a way of estimating the intelligibility which characterizes the communicating environments found in everyday situations. A description of the instrumentation and analysis procedures will be provided. Some comparisons will also be provided between estimated intelligibility and previously recommended levels. [Work supported by EPA.]
From research to regulation: A summing up
Authors: von Gierke Henning E.
Published: October 2005

In spite of the tremendous body of knowledge on the effects of noise on the various aspects of an individual's physical and psychological well being, the quantitative significance of noise to the individual's integrated well being and to society as a whole has hardly been defined. Society's general effort to stem the tide of increasing noise pollution and to work for a quieter environment needs support from the scientific community for sound and cost effective strategies and actions. This summary reviews applications of the research progress presented in this session to recent critical U. S. Governmental decisions to protect society from noise, outlines significant technical progress, and suggests research needs in the area under discussion to support an effective noise control program.
Distinctive feature differences and the effect on the averaged evoked response
Authors: Oshrin S. E. , Powers T. A. , Shallop J. K.
Published: October 2005

Subjects were habituated to a consonant-vowel-consonant (CVC) nonsense syllable, and were subsequently presented with a novel CVC. Response to the novel CVC was measured by averaged evoked response (AER). The novel stimuli were constructed by replacing the initial consonant with another consonant having 1, 2, or 3 distinctive feature differences. Differences in the AER were observed, dependent on the number of distinctive feature differences in the novel CVC. The discriminability of the minimally different CVC's will be discussed in light of the relationships between distinctive feature differences and the changes in the AER.
Detection of temporal gaps in noise as a measure of the decay of auditory sensation
Authors: Penner M. J.
Published: October 2005

The masking of silent intervals, or gaps, by surrounding noise bursts was investigated. The durations (T1 and T2) and the spectrum levels (L1 and L2) of the two noises were varied and the just-detectable gap, ΔT, determined. The paradigm incorporated a replication of Plomp's study [J. Acoust. Soc. Am. 36, 277–282 (1964)]. There were three primary findings. First, by randomizing T1 with T2 fixed and then by randomizing T2 with T1 fixed, it was determined that, if L2<<L1, the difference in the perceived duration of the second noise burst could provide a detection cue. Second, for T1 = 200 msec, changes in T2 did not greatly affect ΔT, suggesting a close relationship between forward masking and gap detection. Third, the slope of the line relating L2 (in dB) to log ΔT was determined as L1 increased with T1 fixed and as T1 increased with L1 fixed. The data indicate that the slope (which reflects the decay of auditory sensation) is controlled by L1 (the spectrum level of the first noise) rather than by T1 (which determines the sensation level of the first noise). It is suggested that the temporal averaging mechanism itself, as well as its output, depends upon the spectrum level of the input. [Work supported by NIH.]
Effects of noise exposure on pulsation threshold curves
Authors: Balthazor R. J. , Cooper W. A. , Feth L.
Published: October 2005

The relationship between pulsation threshold curves and temporary threshold shift (TTS) was studied in normal hearing listeners following exposure to a 105-dB SPL octave band of noise centered at 2000 Hz. Pulsation thresholds were obtained for a 10-dB SL and a 20-dB SL 3000-Hz probe at six masker frequencies (1500, 2250, 2700, 3000, 3300, and 3750 Hz). For each probe sensation level, plots of masker intensity at pulsation threshold comprised the baseline pulsation threshold curves. These pre- and postexposure curves indicated an elevation of threshold and a degradation of frequency selectivity during TTS. While recovery from TTX followed the expected logarithmic pattern, pulsation thresholds remained elevated well beyond the recovery interval for TTS. Our interpretation of these findings supports the analogy between psychoacoustic and physiological measures of frequency selectivity. [Work supported in part by a training grant awarded to the first author by the Veteran's Administration Hospital, Indianapolis, IN.]
Burst intensity and position in the perception of voiced stop consonants
Authors: Bush Marcia , Stevens Kenneth N. , Blumstein Sheila E.
Published: October 2005

Rating scales were used to examine the role of burst intensity and burst position in the perception of the stop consonants [d] and [g]. Bursts and formant transitions were combined to form synthetic CV syllables with conflicting (e.g., d-burst with g-transitions) and nonconflicting (e.g., d-burst with d-transitions) sets of cues. In separate experiments, burst intensity and burst position relative to voicing onset were varied. Subjects were asked to identify and to rate the adequacy of the stimuli with conflicting cues; stimuli with nonconflicting cues were presented in pairs, and subjects rated the adequacy of the consonant of the second syllable relative to that of the first. Within a limited range of burst intensities or positions relative to the following vowel, the nonconflicting burst and transition integrated to form an optimal [d] or [g]. There were substantial individual differences in the way in which subjects responded to a conflicting set of cues. However, results suggest that the conflicting burst is most likely to influence perception when it falls within its optimal range as determined above. [Work supported by NINCDS.]
Prevoicing as a perceptual cue for voicing in Spanish
Authors: Williams Lee
Published: October 2005

Prevoicing, or glottal vibration preceding articulatory release, characterizes only the voiced member of a contrasting voiced-voiceless, work-initial stop consonant pair in Spanish. Then is prevoicing a sufficient or necessary voicing cue for the Spanish listener? Eight monolingual Peruvian-Spanish listeners labeled either "voiced" or "voiceless" synthetically produced, syllable-initial stops for which voice-onset time (VOT) varied from 40 msec of prevoicing to 40 msec of voicing lag. Seven out of eight listeners divided the series into voiced and voiceless portions within the prevoiced region and for six at least 15 msec of prevoicing was required for "voiced" judgments greater than 75% of the time, suggesting that prevoicing can be a sufficient voicing cue when only that provides positive voicing information in Spanish using synthetic speech. Prevoicing was edited from naturally-produced, Spanish, word-initial voiced stops and presented for identification with unedited originals and voiceless minimal pairs to eight Peruvian-Spanish monolinguals. Removing prevoicing did not consistently induce "voiceless" judgments of edited words suggesting that prevoicing is not a necessary voicing cue in real speech. Other properties must supply positive voicing information in its absence.
Fundamental frequency and voice onset time cues to voicing
Authors: Massaro Dominic W. , Cohen Michael M.
Published: October 2005

The acoustic cues that contribute to the perception of the voicing difference in /zi/ and /si/ were the focus of the present experiments. Rather than simply varying the acoustic signal along a single dimension and observing the effect on perception, changes along two acoustic dimensions were covaried in a factorial manner. The time between the onset of the syllable and the onset of vocal-cord vibration called voice-onset time (VOT) was covaried with the fundamental frequency (F0). Observers were asked to indicate where each stimulus fell on a scale from /zi/ to /si/. The results showed that both VOT and F0 contribute to the perception of voicing. Sounds were judged as more /zi/-like with decreases in VOT and with decreases in the F0. The frequency contour of F0 during the syllable had no effect beyond that accounted for by the frequency of F0 at the onset of vocal cord vibration. Other experiments showed that the role of F0 could not be attributed to the possibility that there was less energy at the first formant with higher frequency values of F0. A quantitative model assuming that VOT and F0 are perceived independently and combined multiplicatively provided a good description of the perception of voicing. [Work supported by NIMH.]
Three types of computer models are needed for underwater acoustics
Authors: Wood David H.
Published: October 2005

Since experimental data are scarce and expensive, synthetic data will delineate the capabilities of computer models of sound propagation. Small, fast computer models are the most desirable; but to test their programming and approximations, they must be compared with more powerful but slower computer models. These in turn must be checked against several accurate, dependable computer models having very limited capabilities. Three types of models are required emphasizing (1) operating costs, (2) generality, and (3) correctness. All three types need reporting, documenting, and distributing to facilitate validation of computer models.
Modified ray-theoretical predictions of averaged long-range propagation from near-surface sources
Authors: Smith P. W. , Heine J. C.
Published: October 2005

Wave-theoretical modifications are developed for long-range multipath transmission from sources located in a near-surface layer with large sound-speed gradients. When the WKB approximation fails only in this layer, standard analytical techniques (multipath expansion, the methods of steepest descent) yield modifications to ordinary ray theory in two respects: (i) the range at which a ray appears and the range derivative with respect to ray parameter and (ii) the effective strength of the source. The first is unimportant in a range-averaged calculation. The second can be treated as a modified source directivity and is equivalent to a modified Lloyd's mirror effect. Calculations for typical cases with monopole and dipole sources illustrate the errors of ordinary ray theory. [Work supported by the Naval Electronics Systems Command under Contract N00039-76-C-0023.]
Environmental-acoustics analysis of sound-speed fluctuations induced by internal waves
Authors: Watson J. G. , Siegmann W. L. , Jacobson M. J.
Published: October 2005

An environmental-acoustics model is developed to study the effects on sound speed of a field of small-amplitude internal waves in the deep ocean. The hydrodynamic equations are scaled and a set of approximate equations is obtained. Solutions are determined using a WKB expansion and are shown to be valid in a particular sector of frequency-wave-number space near inertial frequency and zero wave number. Expressions are derived for the sound-speed anomaly produced both by a single internal wave and by a superposition of internal waves over a band of frequencies and wave numbers. The dependence of the single-wave anomaly on frequency and wave number is discussed. In contrast to previous investigations the effects on the superposition anomaly of varying the shape of the internal-wave energy spectrum near inertial frequency and zero wave number are studied. In addition, the influence of the distribution of Brunt-Vaisala frequency (and thus, of mean sound-speed structure) is analyzed for both cases, using analytical models and observational data. [Work supported by ONR.]
Range-dependent normal modes in underwater sound propagation
Authors: Graves R. D. , Nagl Anton , Überall H. , Zarur G. L.
Published: October 2005

A normal-mode method, suitable for practical calculations of transmission loss, has been developed for the propagation of underwater sound in a channel with range-dependent environmental parameters, by employing an adiabatic separation of the wave equation as suggested by Pierce [J. Acoust. Soc. Am. 37, 19 (1975)]. For non-gradual range dependence, coupled range equations are obtained, and a method for uncoupling these by a unitary transformation is being devised. Arbitrary dependence of the velocity profile on depth and range, and of the boundaries on range, can be treated by subdividing depth and range into segments in which the profile and the eigenvalues of the depth equation, respectively, vary linearly. Airy function solutions are obtained in each segment which are evaluated numerically. Results are illustrated using a parabolic velocity profile which opens up with increasing range, as well as more general, numerically defined profiles. [Supported by the Office of Naval Research, Code 486.]
Very-long-range effects of ice-edge noise
Authors: Diachok O. I.
Published: October 2005

A preliminary analysis of synoptic ambient noise and transmission loss measurements in the ice-free subarctic suggests that the ice edge may be represented as a line source of sound, and that the rate of change of noise level with distance from the ice edge is related to the attenuation coefficient [Diachok and Long, J. Acoust. Soc. Am. 56, S17(A), S50(A) (1974)]. Since the low-frequency attentuation coefficient is a subject of current controversy it was felt that further investigations of the low-frequency transmission-loss data was warranted. Based on synoptic airborne bathythermograph data, transmission loss was computed using range-dependent ray theory and the parabolic equation method. (The latter computations were made by J. Hanna of AESD, Washington, DC). Both sets of computations were found to be in reasonably good agreement with measurements. The observed systematic departure from cylindrical spreading was apparently a consequence of the sound velocity structure. In agreement with the preliminary analysis, the departure from cylindrical spreading could be used to “predict” the rate of change of noise level with distance. For this particular data set ice-edge noise at 100 Hz was apparent up to 400 km from the edge.
Measurement of boundary-layer pressure fluctuations at low wave number on a smooth wall
Authors: Geib F. E. , Farabee T. M.
Published: October 2005

Measurements of the spectral density of the wall-pressure fluctuations at low wave number on a smooth wall are presented. The data were obtained with a linear array of six microphones mounted flush in the wall of a wind tunnel specifically designed to have very low background noise levels. The outputs from 4,5, and 6 microphones in the array were combined in a manner suggested by Maidanik and Jorgensen [“Boundary Wave-vector Filters for the study of the Pressure Field in a Turbulent Boundary Layer,” J. Acoust. Soc. Am. 42, 494–501 (1967)] to provide a direct measure of the spectral density as a function of wave number and frequency. Data were obtained at two test locations for a number of flow speeds ranging from 30 ft/sec (9.1 m/sec) to 160 ft/sec (48.8 m/sec) and for frequencies up to 20 kHz. The two test locations allowed the boundary layer displacement thickness to be varied independent of flow speed. A dynamic range greater than 70 dB was obtained at each speed for the magnitude of the spectral density. The magnitude of the spectral density at low wave number is presented in nondimensional form for a range of Strouhal numbers.
Neural basis for sexual differences in the auditory system of the treefrog, Eleutherodactylus coqui
Authors: Narins P. M. , Capranica R. R.
Published: October 2005

The males of the species E. coqui produce a two-note call; the first note (“co”) consists of a constant tone of duration 100 msec and frequency 1.1 kHz, and the second note (“qui”) sweeps upward in frequency from 1.8–2.2 kHz in about 170 msec. Acoustic playback experiments with males and females revealed a behavioral difference in the response of the males and females to the two-note call. These experiments showed that the first note functions in male-male interactions and probably serves to maintain spacing between adjacent males, but does not attract a female. The second note serves to attract conspecific females and apparently plays no role in male-male encounters. An electrophysiological study of the response properties of auditory fibers was conducted in the VIIIth nerve of males and females to determine whether this selectivity could occurs as early as the peripheral auditory system. The results of this study revealed that the functional dichotomy of the two notes in the male's call is reflected by a difference in the distribution of the best excitatory frequencies of primary auditory neurons for the males and females. Furthermore, the Q of the high frequency units showed a distinct difference between the sexes, thus confirming that the basilar papilla in the inner ear is tuned differently in males and females. Eleutherodactylus is the first known example of a vertebrate in which the peripheral auditory system shows a sexual difference. [Supported by NIH Grant NS-09244.]
Adaptation of the peripheral auditory system of CF-FM bats for reception and analysis of predominant components in orientation sounds and echoes
Authors: Suga N. , Neuweiler G. , Jen P. H.-S. , Moller J.
Published: October 2005

In Rhinolophus ferrumequinum and Pteronotus parnellii, each orientation sound consists of long constant-frequency (CF) and short frequency-modulated components. The CF component, which is predominant in the orientation signal, is about 83 kHz in R.f. and 61 kHz in P.p.r. The peripheral auditory system of these bats in terms of CM and N1 is so sharply tuned to the sound at either 83 or 61 kHz, that signal-to-noise ratios significantly increase at these frequencies. The excitatory tuning curves of primary auditory neurons tuned at either 81–86 kHz (R.f.) or 60–63 kHz (P.p.r.) are very narrow. The Q10 dB values, 100 on the average, can be as high as 400. These neurons can code a very minor frequency shift such as ±0.012%. The peripheral auditory system is thus specialized for the reception and free frequency analysis of the predominant component of orientation sounds and echoes. This specialization is not due to suppression or inhibition, but due to the mechanical specialization of the cochlea. [Work supported by NSF.]
Influence of the trumpet mouthpiece on the input impedance of the instrument
Authors: Backus John
Published: October 2005

The mouthpiece of a brass instrument such as the trumpet serves two important functions (among others): that of lowering the frequencies of the higher vibration modes so as to put them in tune, and that of increasing the input impedance of the higher modes so as to make them playable. Acoustically, the mouthpiece consists of a capacitance (the cup) in parallel with a resistance and inductance in series (the orifice and backbore). It has a resonance frequency of the order of 800 Hz. In the vicinity of the mouthpiece resonance, the impedance peaks of the trumpet tube and bell (without mouthpiece) have magnitudes of 200–300 Ω. When the mouthpiece is attached, the resonance frequencies of the combination are lowered to values for which the input impedances of the trumpet tube and bell are small. These low impedances in series with the mouthpiece orifice resistance result in input impedances for the whole instrument which are some 3–6 times the impedances without the mouthpiece. This impedance amplification is essential in order to make the higher modes playable. [Work supported by the NSF.]
Identification of transposed and distorted melodic fragments
Authors: Divenyi P. L. , Hirsh I. J.
Published: October 2005

Listeners were trained to identify one of six possible orders of three tones, equal in duration (mostly 18 msec), at frequencies spaced equally (log) around 1 kHz (f3/f2=f2/f1= ;9/8). When mixtures of these patterns included also transpositions (with same frequency ratios) to as many as 13 different frequency regions, pattern identifiability remained unchanged. When four “background” tones, randomly selected from a 2/3-octave region around 1 kHz, preceded or followed the three-tone pattern [see also Divenyi and Hirsh, J. Acoust. Soc. Am. 57, S10(A) (1975)], identification was impaired only for patterns in the 1-kHz region. Performance improved as pattern frequencies were transposed to regions more remote from the background. Further experiments on isolated patterns increased the pattern “vocabulary” by changing the frequency ratios f2/f1=f3/f2. Pattern identification was best when the span between f3 and f1 was between 1/4 and 1/2 octave and was very difficult for spans less than 1/6 or more than 1 octave. The relations between performance and span for both common (Western music) and uncommon intervals were identical. When frequency ratios were changed asymmetrically (f3/f2≠f2/f1) the degree of asymmetry affected performance when the frequency span was smaller than 1 octave. [Supported by Grant NS03856 from NINCDS to C.I.D.]
Pitch discrimination of ripple pulse trains
Authors: Yost W. A. , Hill Richard
Published: October 2005

A random inteval pulse train when delayed (T) and added back to itself (cos+) produces a cosinusoidally varying power spectrum. The spacing between the peaks in the spectrum are equal to the reciprocal of the delay (1/T). If the pulse train is delayed and added back at 180° phase reversal (cos−), then a cosinusoidally varying power spectrum is generated whose spectral peaks are separated by 1/T, but whose peaks are displaced by 1/2T relative to the power spectrum of the cos+ ripple stimulus generated with the same delay T. These stimuli yield a ripple, or delayed pitch. The pitch of the cos + ripple stimulus is equal to 1/T. The pitch of the cos − ripple stimulus often generates two pitches equal to approximately 0.9/T and 1.1/T. These pitch matching results were studied using a variety of matching stimuli and conditions. Following the identification of the pitches, a method of limits and a same-different procedure were used to study the discriminability of the pitches of both the cos+ and cos− stimuli. Delays T ranging from 1 to 10 msec were studied (covering a pitch range of 90–1100 Hz). The pitch discrimination of the cos+ and cos− stimuli were essentially the same. These pitch discrimination results are compared to those associated with a periodic pulse train. [Work supported by NSF.]
Pitch shifts during pure-tone adaptation
Authors: Larkin W. D.
Published: October 2005

Pitches associated with pure-tone stimuli were measured during gaps in an adaptation tone by a binaural matching technique. The adaptation tone was a sinusoid of moderate loudness presented to one ear at a frequency either very close to or very distant from the test stimuli. During 12-sec gaps in the adaptation tone, listeners adjusted a variable test tone in one ear to match the pitch of a constant comparison tone in the other ear, listening to the test and comparison tones in rapid alternation. With the adaptation tone in the frequency neighborhood of the test stimuli, a small (3% or less) pitch shift was observed. In general, this shift is in a direction which increases the apparent frequency difference between test and adaptation stimuli. This result is in qualitative agreement with similar experiments on the resolution of spatial frequency in vision.
Effect of auditory fatigue on frequency discrimination
Authors: Watson Carol , Melnick William
Published: October 2005

An attempt was made to demonstrate changes in frequency discrimination following a 3-min exposure to a pure tone. Thirty subjects adjusted a variable tone to be just higher or just lower in pitch than a standard frequency. These judgments were made prior to and following exposure to either a 250-Hz or a 4-kHz tone. Three separate standard frequencies were used with each of the exposure tones. When 250 Hz was the fatiguing frequency, pitch judgments were made using 180, 250, and 350 Hz as standards. For the 4-kHz exposure, the standard frequencies were 2.8, 4, and 5.6 kHz. In addition to pitch judgments, the experimental design produced estimates of threshold sensitivity for the test tone. A complete control run was made for each exposure-standard frequency combination. As was the case with previous research in this area, this experimental procedure was unable to show any appreciable effect on frequency discrimination following pure tone exposure. The experiment did produce an interesting secondary observation. There was a distinct asymmetry in the pitch judgments above and below the standard frequency. The asymmetry was particularly noticeable when the standard frequency was 5.6 kHz.
Pitch of acoustically altered whispered vowels
Authors: McGlone R. E. , Manning W. H.
Published: October 2005

The present authors have hypothesized that the perceived pitch characteristics of whispered vowels are related to their second formant frequency [McGlone and Manning, J. Acoust. Soc. Am. 57, 569(A) (1975)]. This assumption was based on the rank-ordering of vowels by judges from highest pitch to the lowest pitch which corresponded directly with the frequencies of F2 of the speakers. To further test the above hypothesis, F2 of vowels/I, i, u, c, æ/ in whispered hV syllables were electronically filtered from the speech signal These altered signals were played in pairs to a group of judges who simply indicated which of the pair had the highest pitch. The vowel quality of the speech sample disappeared but pitch judgments were possible. The order of pitch differed considerably from the unaltered condition. F2 does appear to influence the pitch perception of vowels.
Simulated vs real reverberation in intelligibility testing
Authors: Nabelek Anna K. , Robinette Larry N. , Slawinska Elizabeth
Published: October 2005

Speech intelligibility was tested in various reverberation conditions for normal-hearing subjects. Simulated reverberation was recorded as five echoes following the primary signal (Modified Rhyme Test). These five echoes were distributed over periods of time of 100, 200, or 300 msec. The amplitude of each echo was 6 dB lower than the preceding one resulting in a 30-dB level difference over the total time. Therefore the recordings simulated reverberation times T of 0.2, 0.4, and 0.6 sec (where T is the time for a 60-dB drop). The test was reproduced in a sound-treated room. The comparison of the data for simulated reverberation with previously obtained data for real reverberation indicates that the artificial reverberation did not reduce intelligibility, in the range of parameters tested, while the real reverberation reduced intelligibility about 15%. The difference may be due to the lack of fine structure of multiple reflections in the simulated signal. [Supported by NIH NISND grant.]
Slips of the ear—misperceptions as clues for processing
Authors: Browman C. P. , Goldstein L.
Published: October 2005

Over a hundred naturally occurring misperceptions were collected. An example of a misperception is the case in which the listener perceived “to put up with down” whereas the speaker had produced “to put apples down.” The produced/misperceived utterance pairs can be separated into two categories, those pairs showing evidence of the involvement of higher levels of processing in the misperception (for example, “prodigal son” heard for “popping really slow”) and those pairs not indicating higher-level involvement (for example, “fan” heard for “van” spoken). The severity of the misperceptions, in terms of the number of features differing, is cross-correlated with the position of the misperception (within the word, the syllable, the cluster) and the type of misperception (higher-level processing vs non-higher-level processing). [Work supported by NIH.]
Acoustic fluctuations and internal waves—Are their spectra related?
Authors: Porter R. P. , Spindel R. C.
Published: October 2005

There is little question that internal waves are one source of acoustic fluctuations. However the relationship is complex. A continuous-tone sound field can propagate along many different paths in the deep ocean. Signals traveling along these paths interfere causing fluctuations in time and space. Fluctuation models based on both internal waves and multipath interference have successfully predicted acoustic spectra. For a small number of transmission paths, the acoustic-phase spectrum is directly related to the internal-wave spectrum. Internal waves vertically displace the isotherms causing sound speed perturbations. For a large number of paths or long range, the spectra appear to be dominated by the distribution of acoustic amplitude fades. A discontinuity in acoustic phase, a consequence of an amplitude null, contaminates the high frequency region of the phase spectrum. We present new acoustic data collected with drifting hydrophones and mid-water moorings. These data are compared with predictions of the fluctuation models. Some data, collected with deep hydrophones, are dominated by the distribution of amplitude nulls. Acoustic-phase data, for signals transmitted along a small number of paths, exhibit spectral characteristics predicted by internal-wave models.
Rhythmic effects in perception of continuous speech
Authors: Martin J. G.
Published: October 2005

In experiments measuring reaction time (RT) to phoneme targets in sentences, earlier work produced slower RT when the target was temporally displaced by experimental intervention (computer editing of speech waveform), e.g., artificially extending by 100 msec a pre-stop-consonant silent interval two syllables earlier in the sentence. The result was interpreted in terms of disrupted timing expectancies based on distortion of the prosodic structure, i.e., an interaction between segmental and prosodic cue effects during ongoing perception. In further work, targets in six-syllable nonsense sequences were temporally displaced by lengthening or shortening one vowel in the sequence by various amounts (50–130 msec). The perceptual impression when noticeable is of a sudden shift in speech tempo. RT was measured to phoneme targets in over 600 sequences during several hours of listening. Despite practice and potential cue effects of pre-target manipulations, timing distortions within the first or second pretarget syllable slowed target RT. [Work supported by NIMH, ARIBSS.]
Simultaneous monotic masking as a function of linguistic violations
Authors: Chermack G. D.
Published: October 2005

An investigation was conducted to determine whether grammatical, semantical, and phonological constraints affect aural masking. The rationale for the study centered around conflicting reports in the literature as to the importance of content and linguistic rules for masking efficiency. Thirty-six college-age, normal-heating, native speakers of English participated in six conditions of linguistic masking. Conditions differed in type and degree of linguistic violation of the competing message. Articulation scores computed in percentages served as measures. Significant differences in performance were discussed in terms of information theory, figure-ground and closure concepts, linguistic analysis, attention, memory, and linguistic feature detection.
Instrument for microscopical observation of biophysical effects of ultrasound
Authors: Miller D. L.
Published: October 2005

In this instrument, similar to one used by Harvey [E. N. Harvey and A. L. Loomis, Nature 121, 622–624 (1928)], a quartz driver, thickness resonant at 1 MHz, and a thin cover were concentrically mounted on the stage of a microscope. Electroding was omitted over a central area to allow transmitted-light observation of the test space between them. The acoustic field generated in the cylindrical test volume, of radius 2.225 mm and height 1.28 mm, was approximated by a standing-wave solution to the linearized wave equation. The boundary values were (i) zero pressure at the radial boundary and (ii) interferometrically determined values of the acoustic displacement at the driver and cover. The truncated-series solution for the pressure agreed with independent measurements obtained by interferometrically detecting (via the acousto-optical effect) the pressure oscillations, averaged over height, occurring in the waterfilled test space.
Portable instrument for thermal measurement of total power output from ultrasonic diagnostic equipment
Authors: Herman B. A. , Stewart H. F.
Published: October 2005

It is important to be able to determine the ultrasonic power radiated by diagnostic equipment in the clinical environment, without unduly interrupting patient scheduling. This presentation describes a portable, thermal system which can measure ultrasonic power at diagnostic levels. This technique utilizes a nickel, parabolic reflector to focus the ultrasonic beam onto the sensing element, a thin-film thermistor. The “thermistor” is mounted on sound absorbing rubber, and the rise in temperature upon insonation is measured with a simple bridge circuit. One arm of the bridge is another thermistor mounted near the insonated chip but outside of the ultrasonic beam. Maximum sensitivity of this device is 100 μW average power and beams up to 0.75 in. diameter may be accommodated. Time for each measurement is approximately 5 min. The instrument was calibrated using a Mettler-balance radiation force method.
Experimental wide-band hearing aid
Authors: Killion Mead C.
Published: October 2005

A simple bridged-T equalization network and the “6-kHz earmold” described elsewhere have been used in conjunction with recently introduced wide-band transducers to construct an experimental behind-the-ear hearing aid with extended bandwidth. The resulting frequency response is smooth and (after correcting for head and ear-diffraction effects) approximately uniform up 1500 Hz, with a 10-dB boost in the 2–6-kHz region. A comparison of the frequency responses obtained on the 2-cc coupler, on “KEMAR”, and by subjective tests,indicates good agreement with previous head and ear-diffraction studies. [Work supported by Industrial Research Products, Inc., Elk Grove Village, IL and Central Institute for the Deaf, St. Louis, MO.]