bluuebunny/crossref_metadata_2025 huggingface dataset:
Adaptation of the acoustically emitted 2f1−f2 combination tone
Authors: Dolan Thomas G. , Abbas Paul J.
Published: October 2005

Recent studies suggest that the 2f1−f2 ear-canal distortion product is produced by nonlinearities in the motion of the cochlear partition. Given its cochlear origin, we attempted to use the acoustically emitted combination tone (ACT) to indirectly examine changes in cochlear mechanics that may be associated with long-term adaptation (i.e., adaptation lasting several seconds) of eighth-nerve responses. We examined the effects of 1-min tonal exposures the amplitude of the 2f1−f2 ACT in the ear canals of cats. These effects were compared with post-exposure changes in the whole-nerve action potential (AP) responses to tone bursts that resulted from similar exposures. Both the distortion product and N1 amplitudes were reduced for several seconds following exposure. The reduction in ACT amplitude suggests that 1-min exposures can alter cochlear mechanics. The fact that the same exposure tones cause reductions in N1 amplitude further suggests that neurally measured long-term adaptation is linked to changes in the mechanics of transduction. The time courses of ACT and AP recovery were similar, and the post-exposure effects depended in similar ways upon the frequency and intensity of the exposure tone. These results suggest that both the ACT and AP post-exposure effects are reflections of the same underlying cochlear process.
Long-term stability and familial aspects of spontaneous otoacoustic emissions (SOAEs)
Authors: Strickland E. , Burns E. M. , Tubis A. , Jones K.
Published: October 2005

The frequencies and levels of SOAEs in six subjects were monitored several times weekly (in some cases daily) over a period of several months. One additional subject was monitored over a period of about two years. The stability of individual emissions varies widely both within and between subjects (e.g., the standard deviation of repeated measures of frequency varies from about 0. 1% to over 1.0%), and appears to be unrelated to either the frequency or the level of the emission. The frequency and level shifts of individual emissions in an ear with multiple emissions appear to be independent with one exception, the case when an emission is apparently a distortion product resulting from the interaction of two other emissions. In this case the frequency of the “distortion” emission depends on the frequencies of the “primary” emissions. A survey of emissions in children was also undertaken. The incidence of SOAEs in children is fairly common and in all cases to date in which multiple emissions were found in a child. at least one of the parents also had multiple emissions. We have also identified at least one family of the type described by Glanville et al. [J. Oto. Laryngol. 85, 1–10 (1971)] in which several siblings all have very high level (40 dB SPL) high-frequency emissions. [Work supported by NINCDS.]
The relationship of threshold fine structure to spontaneous and evoked otoacoustic emissions
Authors: Bums E. M. , Strickland E. , Jones K. , Tubis A.
Published: October 2005

Pure-tone thresholds at intervals of 10 Hz were obtained in a number of subjects with single or multiple spontaneous otoacoustic emissions (SOAEs). In all cases the SOAE frequencies corresponded to frequencies at which threshold minima occurred, and the subjective impressions of the listeners for frequencies in the region of SOAEs corresponded to known aspects of the interaction of external tones with SOAEs; i.e., distortion products, beats, and frequency locking. However there were always more threshold minima than SOAEs. In some cases these minima corresponded to the frequencies of distortion products, resulting from the interaction of two SOAEs, which were apparently below the noise floor of the measurement system. In other cases the minima corresponded to frequencies at which evoked otoacoustic emissions (EOAEs) occurred. However there were usually minima which were not “explained” by any of these correspondences. The results will be discussed in light of current cochlear models. [Work supported by NINCDS.]
Potassium-induced release of glutamate and taurine into perilymph is calcium-dependent
Authors: Jenison G. L. , Bobbin R. P. , Thaimann R.
Published: October 2005

Perfusion of the choclea with artificial perilymph containing high concentrations of potassium chloride selectively induces the release of several different endogenous amino acids [Neurosci. Abstr. 16.1 (1983)]. This study examines whether such augmentations reflect the liberation of neurotransmitter(s) from depolarized hair cells by comparing potassium-induced changes in amino acid levels evoked under normal divalent ion conditions (2.0 mM Ca+2−1.0 mM Mg+2) to the effects of potassium elicited under conditions known to antagonize evoked transmitter release (0.1 mM Ca+2−20.0 mM Mg+2). For each condition, high performance liquid chromatographic analyses were conducted on artificial perilymph samples collected before, during, and after the perfusion (scala tympani →scala vestibuli) of 50-mM potassium perilymph. Analysis of variance and subsequent Newman-Keuls multiple range tests were conducted on mean sample concentration values (N = 5/condition) for each of 17 endogenous amino acids. Exposure to 0.1 mM Ca+2−20 mM Mg+2 resulted in attenuations of evoked release only for amines identified as glutamate (− 39.6%,p = 0.005) and taurine ( − 48.2%,p = 0.003). These data support the candidacy of glutamate and taurine as auditory receptoneuronal neurotransmitters or transmitter metabolites. [Supported by NIH Grants NS-06575, NS-16080, NS-07058, and NSF Grant BNS-8118772.]
Pulsation threshold patterns of synthetic vowels: Study of the second formant emergence and the center of gravity effects
Authors: Escudier Pierre , Schwartz Jean-Luc
Published: October 2005

Very small spectral irregularities are detected by the auditory system, thus suggesting the existence of a derivation-like mechanism. We have already shown this fact by the estimation of formant detection thresholds in relation to the spectral pattern of a given reference [Lublinskaya et al.], J. Acoust. Soc. Am. Suppl. 1 67, S102 (1980)]. On the other hand, the center of gravity phenomenon suggests the existence of an integrationlike mechanism [Lublinskaya et al., Acts of the “Symposium Franco-Soviétique de Grenoble,” 19–20 (1981)]. These two facts have been studied by means of pulsation threshold techniques. We have obtained psychophysical estimations of the internal representation of vowel-like spectra, to see how these two opposite spectral mechanisms are combined, and at what level of the auditory system they are susceptible to appear. This kind of information is necessary for the elaboration of auditory perception models.
Perceptual segregation of simultaneous vowels presented as steady states and as parallel and crossing glides
Authors: Halikia Magdalene H. , Bregman Albert S.
Published: October 2005

Recent research with synthesized pairs of simultaneous vowels, that had similar or different F0s and steady-state inflections has shown that the F0s must differ by more than 1–2 semitones in order for the vowels to be heard separately [M.T.M. Scheffers, IPO Ann. Prog. Rep. 17, 41–45 (1982)]. The present study investigated the combined effects of F0 differences and steady state or gliding (with the glides parallel or crossing) inflections on the perceptual segregation of simultaneous vowels. The stimuli were four vowel sounds synthesized using a serial three-formant method. Six basic pairs were the result of all possible combinations of these vowels, taken two at a time. Further pairs were created by altering the F0 of each vowel (so that the two F0s differed by 12, 3, 6, 12 semitones) and by keeping the F0 at a fixed frequency level (in the steady state case) or by making it glide between two different frequency values (in the glide case). Subjects had to identify the two vowels in each pair. It was expected that we would get better results with the glides since their formants are better defined because the harmonics will shift through the spectral envelope. We were also interested to see whether the direction of the glide is important in the perceptual segregation. The results confirmed our hypothesis and also showed that a minimum F0 separation is necessary before the use of glides can have an effect. The crossing glides gave significantly superior results over the parallel glides at the octave frequency separation of their F0s.
A comparison of spectra of loud and whispered speech
Authors: Náb̆elek Igor V. , Maroonroge Sumalai
Published: October 2005

Spectra of running speech of eight female subjects were determined for two conditions: loud reading and reading of the same text in whispered mode. The subjects were seated in a sound isolated booth. A 12-in. measuring microphone was 10 cm from the lips of the reader. The spectrum analyzer Nicolet UA 500 A was employed. The average spectrum of the eight subjects had a pronounced maximum at 300 Hz when the speech was loud. Between 500 and 1200 Hz the slope was around −17 dB/oct, and between 1.8 and 14 kHz the slope was −3.7 dB/oct. The whispered speech had very similar spectrum in the upper frequency range mentioned above. The spectrum had the same average slope. Below 1000 Hz the average whispered speech spectrum was rather flat. The differences between whispered and loud spectral levels in this range reached around 20-dB values.
A multispeaker analysis of duration in read French paragraphs
Authors: O'Shaughnessy Douglas
Published: October 2005

An understanding of natural language durations will lead to more intelligible synthetic speech, and to improved automatic recognition. Toward this goal, a I I I-word paragraph was read by 29 native French speakers. A pitch-extractor device plotted the speech amplitude waveform, at an average rate of 55 mm/s. Durations were measured to the nearest 5 ms, with a measurement error of about 10 ms (1/2 mm). Phoneme durations were found to be significantly shorter than those in stressed words from sentences pronounced in isolation [D. O'Shanghnessy, J. Phon. 9, 385–406 (1981)]. Previous trends (short schwa vowels and grammatical words, long unvoiced fricatives, nasal vowels, and prepausal syllables) were confirmed. Vowels lengthened preceding voiced fricatives (but not prior to /r/, and lengthened more at sentence-internal pauses than at the end of a sentence. Standard deviations of phoneme durations (at a fixed position in the paragraph) across speakers averaged about 20% for consonants and 25% for vowels. A generative model of French durations will be presented. [Supported by NSERC and the France-Quebec exchange.]
Word-frequency effects in modified rhyme test responses
Authors: Webster J. C.
Published: October 2005

Four (of six) lists of a recorded six-choice MRT made up of 10 numeral, 10 vowel (V), 15 initial consonant (IC), and 15 final consonant (FC) items were administered to 15 groups of 20 severely/profoundly deaf young adults. Analyses were made of the 960 non-numeral-item responses (4 lists × 6 foils × 40 items). The percentage of subjects choosing the correct response dropped from 47.98 for the Vs to 42.16 for ICs to 38.36 for FCs. Of the remaining 800 responses (errors), 89 were chosen by over 20% of the students. Confusions of voicing (V), manner (M), and particularly place (P) would be expected to explain the majority of the 70 greater-than-chance (GTC) errors among the 600 IC and FC responses. Place confusion did account for the majority of the 39 FC GTC errors. However for the 31 GTC IC errors, and the 19 GTC V errors, the relative word familiarity interacted with VMP explanations. Twenty-eight of the 89 GTC errors could not be accounted for by either VMP confusions or word familiarity. Of these, six were confusions among /w,l, and r/.
Quantifying lexical redundancy effects in word recognition
Authors: Boothroyd Arthur , Nittrouer Susan
Published: October 2005

The goals were to test two equations reflecting the effects of lexical redundancy on recognition probability, and to derive typical values for constants appearing as parameters in these equations. pc = 1 − (1 − pi)k, where pc and pi are recognition probabilities with and without lexical redundancy, and pw = pp, where pw and pp are the recognition probabilities for whole words and phonemes within words, respectively. Using phonemically balanced lists, word and phoneme recognition was measured, in normally hearing subjects, at four S/N levels and five word-frequency levels. Analysis of variance confirmed that j and k were relatively independent of S/N ratio, but highly dependent on word frequency. Values of j ranged from 3.1 for nonsense words to 2.3 for high-frequency words. Values of k were 1.3 for phoneme scores and 2.3 for word scores. These data confirm earlier findings indicating that phoneme scores are less influenced by lexical redundancy than are word scores. They also support the model underlying the theoretical equations and provide a means of predicting one type of score from another. [Work supported by PSC. CUNY Award ♯6-63137.]
Using DECtalk as an aid for the handicapped
Authors: Klatt Dennis H. , Tiao Julie , Tetschner Walt
Published: October 2005

DECtalk is a commercial test-to-speech system with general interface capabilities to any of a number of terminals and computers. As an aid for the vocally handicapped, it has advantages over devices used previously in that any of several different voices, simulating men, women, and children, can be selected and modified to create a personal voice. Preliminary attempts to provide DECtalk to selected users have met with enthusiastic responses, particularly in women and children, who have had to use a male voice in the past. As an aid for the blind, DECtalk can replace the voice in presently available reading machines for the blind. While DECtalk is currently undergoing formal intelligibility testing by D. Pisoni, it is clear from side-to-side comparisons that such a switch improves both intelligibility and the naturalness of the voice. In addition, J. Tiao has been developing a talking text editor for blind computer professionals and others who may now become more productive in the workplace. The program uses DECtalk and a Rainbow personal computer to create and modify text files. [Work supported in part by an NIH grant.]
Perception of vowel quality in the presence of other sound sources
Authors: Darwin Christopher J.
Published: October 2005

If the energy of a harmonic (500 Hz) near the first formant of a vowel is increased, the vowel quality changes. But if the tone corresponding to this increase in energy starts or stops at a different time from the original vowel, then listeners can perceive the original vowel quality [Darwin, Attention and Performance, Vol. X (Erlbaum, 1983)] even though the spectrum present during the vowel is inappropriate. Listeners apparently partition the total sound present into separate percepts on the basis of onset- and offset-time differences. The present experiments show that the same partitioning still occurs when the “original” vowel has reduced energy at 500 Hz. Now adding extra energy to it restores a normal vowel spectrum. Listeners report a vowel quality corresponding to the “original” depleted vowel when the additional energy starts or stops at a different time from the rest of the vowel, even though the spectrum present during the vowel is appropriate to a vowel with a normal spectral envelope. The partitioning of sound sources observed here cannot be explained by a tendency to perceive vowels with conventional spectral envelopes. [Work supported by SERC.]
Multidimensional scaling and perceptual features: Reflections of stimulus processing or long-term memory prototypes?
Authors: Fox Robert Allen
Published: October 2005

Many researchers have obtained information on phonetic perception by using various multidimensional scaling (MDS) procedures to discover underlying perceptual dimensions. Such dimensions are usually characterized in terms of the acoustic characteristics of the stimuli and have been interpreted as representing factors used to identify vowel (or consonant) quality in phonetic perception. However, several studies suggest that such dimensions may reflect properties of the vowel's long-term memory prototype rather than the actual acoustic nature of the stimuli. For example, MDS studies commonly find no features reflecting dynamic acoustic information [e.g., R. Fox, Lang. Speech 26, 21–60 (1983)] and one study [B. Rakerd, J. Acout. Soc. Am. Suppl. 1 73, S54 (1983)] found that similar perceptual features were extracted when Ss either heard or imagined remembered) stimulus tokens. To investigate this issue an experiment was designed to determine the extent to which slight acoustic variation in a subset of the synthetic vowels presented to Ss for scaling would produce differences in perceived perceptual distance estimates. Results suggest that Ss are sensitive to relatively small acoustic differences while making dyadic comparisons even when there is no concomitant phonemic quality variation or specific instructions expect such variations. It will be argued that such results suggest that MDS procedures do tap lower-level perceptual processes and do not merely reflect long-term memory prototypes.
The influence of postvocalic consonants on the duration of Spanish vowels
Authors: Massone Maria Ignacia , Borzone de Manrique Ana Maria
Published: October 2005

The present work was undertaken in order to provide further evidence about the role played by the physiological and phonological factors in vowel lengthening before voiced consonants. Previous experiments compared cross-linguistically different consonantal contexts and syllabic types, but, with respect to Spanish disregarded neutralization in final syllable position. Two male adults recorded nonsense bisyllabic words and two other speakers recorded meaningful frequent words where the opposition voiced/voiceless was spontaneously neutralized. Results showed that in open and closed syllables of nonsense utterances (average ratios: 1.4 and 1.23, respectively) vowels are shorter before voiceless consonants than before voiced. In meaningful words, vowels presented longer duration before voiced realizations (20%) of lengthening. However, for nonsense utterances, higher values were obtained and we can assume that this difference is indicating some phonological effect. The lengthening value observed in meaningful words seems to represent more closely the physiological effect.
Vowel information is integrated across intervening nonlinguistic sounds
Authors: Whalen D. H. , Samuel Arthur G.
Published: October 2005

When the fricative noise of a fricative-vowel syllable is replaced by a noise from a different vocalic context, listeners experience delays in identifying both the fricative and the vowel (D. H. Whalen, Perception & Psychophysics, 1984). Listeners (unconsciously) detect a mismatch between the vowel information in the fricative noise and in the vocalic segment. In the current experiment, noises and vowels were again cross-spliced, but, in addition, the first 60 ms of the vocalic segment either had a nonlinguistic noise added to it or was replaced by that noise. The fricative noise and the majority of the vocalic segment were left intact, and both were quite identifiable. Mismatches of vowel information caused delays for all stimuli, both originals and ones with the noise. Additionally, syllables with a portion replaced by noise took longer to identify than those that had the noise added to them. The results indicate that listeners integrate all relevant information even across a nonlinguistic noise. Similarly, having the signal present along with the noise delayed identifications less than replacing the signal completely. [Work supported by NIH.]
Dynamic specification of vowels in CVC syllables spoken in sentence context
Authors: Strange Winifred
Published: October 2005

In previous studies of citation-form /b/-V-/b/ syllables, vowel identification accuracy of “silent-center” syllables (in which steady states were attentuated to silence) was not significantly worse than for unmodified control syllables [W. Strange et al., J. Acoust. Soc. Am. 74, 695–705 (1983)]. New studies were performed in which vowels were produced in /b/-/b/, /d/-/d/, and /d/-/t/ syllables, spoken in a carrier sentence, “Say the word ---- again.” Silent-center syllables, in which all but the first three and last four pitch periods were attenuated to silence, were identified with 85% accuracy, as compared to 97% for control syllables. However, vowel identification was still much more accurate than when either the initial transitions or final transitions were presented alone (54% and 37% accuracy, respectively). Performance on silent-center syllables was not significantly better when subjects were presented the stimuli blocked according to consonantal context (87%). Neutralizing syllable duration differences decreased accuracy somewhat (78%), especially for short vowels. Additional identification studies are underway in which portions of syllables containing different consonants were interchanged, in order to test hypotheses about trajectories specified by initial and final transitions. [Work supported by NIMH.]
Vowel perception in reverberation
Authors: Nabelek Anna K. , Letowski Tomasz
Published: October 2005

Because identification of vowels was not affected by reverberation, possible changes in perception were assessed in a paired comparison paradigm. Fifteen English vowels and diphthongs recorded with and without reverberation (T = 1.2 s) were paired with each other. Ten normal-hearing subjects made similarity judgments using a scale from 1 to 7. Response matrices for the two conditions were analyzed using multidimensional scaling procedures. A three-dimensional solution was sought for the data on the basis of the experimental conditions and results of previous studies. Three- and two-way analyses were performed using a ALSCAL subroutine. Both with and without reverberation, the first two dimensions were identified as back-front and low-high, confirming the results of previous studies. The third dimension was identified as long-short while others interpreted it as tensness, openness, or left it unidentified. In both three- and two-way analyses, the shifts in stimulus configuration between test and retest and between reverberant and nonreverberant solutions were of the same order. Therefore, we concluded that reverberation did not contribute significantly to the perceptual distances among vowels and diphtongs. [Supported by NIH.]
The “center of gravity” and perceived vowel height
Authors: Specter Beddot Patrice , Hawkins Sarah
Published: October 2005

In oral vowels, perceived height is determined by the “center of gravity” of the spectral prominence in the vicinity of F1 rather than by F1 peak frequency [Chistovich and Lublinskaya, Hear. Res. 1, 185–95 (1979)]. The present study of nasal vowels assessed the generality of the center of gravity effect. Five nasal vowels,/ɪ̄ ē ǣ ā ō/, were synthesized. For each nasal vowel, a continuum of corresponding oral vowels was synthesized by manipulating the frequency of F1. Each continuum included one stimulus whose F1 frequency matched that of the nasal vowel and one whose centroid (a measure of center of gravity) matched. The five vowel sets consisted of oral-nasal vowel pairs; 20 listeners selected the “best-match” pair for each set. Subjects chose the F1 match for /ɪ̄/ only; for nonhigh vowels, choices fell between F1 and centroid matches, but significantly closer to the centroid. Apparently center of gravity influences perception of nasal vowel height, but the centroid as a measure of this needs refinement. Whether the centroid is an appropriate measure of perceived oral vowel height, or whether another metric applicable to both oral and nasal vowels can be found, is currently under investigation. [Work supported by NIH.]
Acoustic wave motion in the human pinna at high frequencies
Authors: Kuhn George F.
Published: October 2005

Localization studies have shown that spectral peaks as well as spectral nulls formed by the pinna are significant localization cues. Experimental results from real and from model pinnas as well as theoretical predictions, using the uniform theory of diffraction, show that the first null is formed via a single reflection within the pinna. This first null rotates with increasing frequency from an angle in the lower frontal quadrant to an angle in the upper frontal quadrant starting at as low a frequency as 4.5 kHz, depending on the size and geometry of the pinna and the particular location of the earcanal. As the frequency is increased, additional nulls and peaks are formed which rotate from the lower rear quadrant to the upper rear quadrant. These nulls and peaks are formed by the interference of edge-diffracted waves with multiply reflected waves within the pinna cavities. Both the measured and predicted pressure patterns in the pinna correlate well with psychoacoustic studies of vertical, median plane localization. [Work supported by NIH.]
The combination of interaural information across frequencies: Lateralization on the basis of interaural differences of time
Authors: Dye Raymond H. , Baumann Joseph N.
Published: October 2005

The basic question addressed here is how the binaural auditory system combines interaural differences of time (IDTs) arriving over multiple bands of frequencies. An initial study was undertaken to measure threshold IDTs for three-component stimuli with the middle component at 750 Hz. The frequency difference between components was 20, 50, 100, 250, or 450 Hz. After measuring thresholds for the individual components presented alone, measures were taken for the three-component complexes when only the lower, middle, or upper component was delayed; when the lower two components, the upper two components, or the sidebands were delayed; and when all three components were delayed. Best performance was obtained when all three components were delayed, regardless of Δ f, although the differences between Δ IDTs obtained when all three components were delayed and when the “best” (i.e., smallest thresholds) frequency of the complex was presented alone were small. When only two of the three components are delayed, thresholds approach those obtained when all three components are delayed, as long as one of the delayed components was the best frequency of the complex. When only one component of the complex was delayed, thresholds were 2–5 times higher than when the same component was presented alone. The data will be discussed in terms of a binaural mechanism which lateralizes acoustic images by taking a weighted average of information arriving from different frequency channels. [Work supported by NSF.]
Accuracy of sound localization by the frog Hyperolius marmoratus
Authors: Capranica R. R. , Passmore N. I. , Telford S. R. , Bishop P. J.
Published: October 2005

The sound localization ability of female painted reed frogs was studied by phonotactic approaches via a three-dimensional grid to an elevated loudspeaker (through which male mating calls were broadcast). Females readily resolved the sound source elevation with a mean jump error angle of 37&° (26 trials, 17 females), compared to a mean jump error angle of 19° (33 trials, 13 females) for a more conventional two-dimensional ground approach. Lateral head scanning, often accompanied by vertical changes in head orientation, frequently preceded successive jumps. The ability of such small frogs to accurately localize a sound source in both the horizontal and vertical plane, given the absence of a pinna or external canal, is remarkable. [This study was supported by the South African Council for Scientific and Industrial Research, and the Animal Research Program, University of the Witwatersrand.]
Acoustic coding by the ear of the sunfish (Lepromis gibbosis): Sensitivity, tuning, and directionality of 8th nerve units
Authors: Coombs Sheryl , Ray Richard R.
Published: October 2005

The auditory system of the sunfish is characteristic of many teleosts, and is unspecialized for sound pressure reception. It is likely that its otolithic ear responds primarily to acoustic particle motion in the manner of an accelerometer. Single units of the lagenar and saccular eighth nerve branches were characterized in response to whole-body acceleration. Using a three-dimensional vibration system [Fay et al., J. Acoust. Soc. Am. Suppl. 1 74, S7 (1983)], the directionality of single units were measured in three orthogonal planes, and the cell's best sensitivity axis determined in spherical coordinates. Acceleration tuning curves obtained along a nearly optimal axis were essentially low pass with cutoff frequencies ranging from below 100 to 250 Hz. Best sensitivity varied from −30 to −90 dB re: 1 g (rms). Lagenar units showed a wide range of “best directions,” all roughly in a para-saggital plane. Saccular units fell into two or more directional groups. Directional patterns for both organs reflect aspects of the organs' orientation in the head, and the orientations of hair cells on the maculae. All cells reponded as if their input (most likely a group of hair cells) were equivalent to a single hair cell of a given three-dimensional orientation.
Physiological noise and the determination of vibro-tactile perception thresholds
Authors: Piercy J. E. , Brammer A. J. , Taylor W.
Published: October 2005

Several physically different configurations are frequently used to couple sinusoidal vibration to the finger or palm for the determination of vibro-tactile perception thresholds (viz: exciter diameter and contact surface curvature, contact force and skin indentation, and the presence or absence of a surround). Vibration of physiological origin (physiological noise) has been studied in the frequency range 0.025–1000 Hz for several common configurations. The acceleration spectrum consists of a broad plateau between 0.1 and 10 Hz, with peak amplitude ∼0.01 to 0.1 m/s2 (with reference to 1-Hz bandwidth) depending on the configuration and subject. The spectrum falls rapidly with increasing frequency above 10 Hz. Substantial contributions to the physiological noise can be identified from blood circulation (1–10 Hz) and respiration (0.2–1 Hz). Preliminary psychophysical results from three subjects, when combined with current knowledge of the masking of vibrotactile signals, suggest that vibrotactile thresholds at frequencies well above 10 Hz may be masked by this physiological noise under some conditions of flesh stimulation.
Effects of skin temperature and body site on psychophysical characteristics of cutaneous mechanoreceptor subsystems
Authors: Verrillo Ronald T. , Bolanowski Stanley J.
Published: October 2005

Psychophysical detection thresholds were obtained at the thenar eminence and volar forearm using 16 sinusoidal frequencies between 15 and 700 Hz. A small (0.008 cm2) contactor was used, which preferentially excites non-Pacinian (NP) subsystems. Measurements were made using carefully controlled (± 0.5 °C) skin surface temperatures of 15°, 20°, 25°, 30°, 35°, and 40 °C to enhance or degrade the subsystem responses. The results show several frequency characteristics that cannot be ascribed to activity in the Pacinian system, but do conform to electrophysiological measurements of Ruffini capsules, Meissner corpuscles, and Merkel cells. When threshold values are averaged across temperatures, the resultant curve is approximately flat. The results suggest that the NP system is probably composed of more than a single receptor type and that well-controlled skin temperature is necessary for the precise measurement of vibrotactile sensation.
Real-time extraction of vocal quality parameters from electroglottographic signals
Authors: Hasegawa Akira , Mahshie James , Herbert Eugene , Brandt Fred , Mars Marguerite , Pickett James
Published: October 2005

This paper reports the second phase of our efforts to efficiently and effectively parametrize the electroglottographic (EGG) signal for monitoring and modification of deaf speech. The first phase [real-time extraction of the voice fundamental frequency (F0)] was reported at a previous meeting. Our EGG, pneumotachographic, and cinematographic observation of the vocal fold movement revealed systematic changes in the duration of the vocal fold contact with respect to characteristics of the individual movement cycle. Reduced contact typically reflects breathier voices, which are common among deaf speakers. The parameter extraction system under development consists of an EGG, a linear phase high pass filter, a custom-made signal conditioner/parameter extractor, and a PDP 11/34A computer. Additional hardware is used for display and storage of the extracted parameters. Details of the extraction scheme and the results of modification of vocal quality using the visual display will be presented. [Study supported by the National Institute of Handicapped Research and the Gallaudet Research Institute.]
Recent advances in the understanding of acoustic transmission through the walls of air conditioning ductwork
Authors: Cummings Alan
Published: October 2005

Acoustic noise transmission through the walls of air conditioning ductwork has long been a neglected aspect of HVAC acoustics, but two recent ASHRAE-sponsored research projects have done much to rectify the situation. The results of this work are described here, and include both experimental data and prediction methods concerning interior/exterior noise transmission (“breakout”) through the walls of plain, unlined rectangular, flat-oval, and circular ducts; the measured and predicted breakout insertion loss (IL) of external acoustic wall lagging on ducts of these three geometries is also discussed. Noise transmission into ducts (termed “breakin”) is of importance too, and a simple theoretical treatment is available, enabling the breakin transmission loss (TL) of the duct walls to be found from the breakout TL. In addition, the calculation of sound pressure levels in rooms, from duct wall radiation, is discussed here. The prediction methods of the wall TL of rectangular and flat-oval ducts are simple to use and are fairly reliable; circular ducts are, however, difficult to cope with at present. The prediction of the IL of lagging on all duct geometries is straightforward and reasonably accurate. The “state of the art” in duct wall radiation is also discussed here.
Analysis of nonlinear harmonic generation for arbitrary dual frequency transducer excitation
Authors: Foda Mosaad A. , Ginsberg Jerry H.
Published: October 2005

An earlier study of finite amplitude axisymmetric sound beams [J. H. Ginsberg, J. Acoust. Soc. Am. Suppl. 1 73, S83 (1983)] considered the case of monochromatic excitation. That work featured a singular perturbation analysis combining asymptotic integration and the renormalization version of the method of strained coordinates. The present paper initiates an extension of those techniques to the case of a dual frequency source. The parametric array, in which the primary beams are at closely spaced frequencies, has already received much attention. The system discussed here permits disparate frequencies. Aside from a restriction to axisymmetry, the excitation at each frequency is arbitrary. The analysis thus far has obtained the first two orders of approximation for the velocity potential. This expression describes the manner in which nonlinear effects accumulate for the various sum and difference frequencies. It is the foundation for a future derivation of an expression for the pressure that is descriptive of the entire field. In addition, the trend for harmonic generation indicated by the analysis suggests that conversion efficiency in the parametric array might be improved by altering the transverse vibration pattern of the individual primary beams. [Work supported by ONR, code 425-UA.]
Time domain observations of finite amplitude random noise
Authors: Welz Joseph P. , McDaniel Oliver
Published: October 2005

A research program has been conducted to study nonlinear effects in noise propagation from supersonic jets. Two microphones were used to measure spherically diverging finite amplitude noise from a 10-kW acoustic source. One microphone was located at a fixed position near the source and the second microphone was moveable by remote control. Observations of finite amplitude distortion of individual wave trains were made using two digital signal processing techniques. First, the time delay between the two microphones was determined by computing the crosscorrelation function. This procedure proved to be considerably more accurate than determination of time delay from measurement of microphone spacing and computation of sound speed using chamber temperature. The instrumentation system was then programmed to capture the same wave train sample from both microphones utilizing the time delay information. The experimental results were in good agreement with a numerical time domain solution to Burger's equation. Spectra obtained by Fourier transform of the theoretical and experimental results also agree well. [Work supported by NASA Langley Research Center.]
Use of synthetic speech parameters to estimate success of word recognition
Authors: Ohala John J. , Amador Mariscela , Araujo Lynn , Pearson Steve , Peet Margot
Published: October 2005

In an automatic speech recognition task, it would be good to estimate beforehand how recognizable the target vocabulary will be. Tests which involve numbers of human speakers using the ASR device are expensive and time consuming. Using stimuli synthesized by rule, although not without some drawbacks, would be cheaper and quicker. As a first step towards this latter goal we attempted to find out whether measures derived from rule-synthesized words would predict human listeners' performance in recognizing target words in continuous speech embedded in noise. Even a very simple measure of word detectability (essentially the length of the word's trajectory through the space whose dimensions are normalized F1, F2, F 3, and rms amplitude) correlated significantly with listener's performance (r = 0.53). The results of refined measures of detectability and the results of word confusability will be reported.
Fundamental frequency characteristics of deaf speakers
Authors: Mahshie James , Hasegawa Akira , Mars Marguerite , Herbert Eugene
Published: October 2005

Fundamental frequency (f0) characteristics of deaf speech appears to differ from normal, although the extent and nature of these differences is unclear. Fundamental frequency characteristics are dependent upon the way the speech sample is elicited (spontaneous or read). This study examined the f0 characteristics of 25 deaf and 10 normal-hearing adults during various speaking tasks, including spontaneous speech, oral reading, and declarative sentence and yes/no question production. Comprehensive descriptions of f0 were obtained by means of a computer based f0 measuring and analyzing system developed at Gallaudet College. These descriptions included: (1)f0 distribution, (2) measures of central tendency, (3) distribution variance, (4) estimates of f0 range, and (5) cycle-to-cycle f0 change. Results show that the f0 characteristics of the hearing-impaired subjects differed from normal, and that the hearing-impaired subjects tend to alter f0 characteristics among the different speaking tasks to a lesser extent than normal-hearing subjects. Implications of findings will be discussed. [Research supported by the National Institute for Handicapped Research and the Gallaudet Research Institute.]
Critical band for frequency: A revision of the limits
Authors: Solowan J. Douglas
Published: October 2005

Numerous music acoustics and psychomusicology text books claim that it is not possible to hear the individual pitches when two simultaneous tones are separated by a half-step. Musicians, on the other hand, find that their day-to-day experience does not correspond well with this claim. Remarkably little research literature was found which tests this question in a musical situation. Because this task pits the information available in the frequency domain and that available in the time domain in opposition, it is important to determine who is right. The results of a test in which subjects used the method of adjustment to match a tone to either of two, simultaneous tones are presented. These subjects qualified to take the test by demonstrating fine-tune pitch matching ability to a single tone. In contrast to the previously accepted limit of frequency discrimination, the results indicate that the subjects were able to effectively analyze one of the pitches out of a two-tone stimulus whose frequencies were as little as one-quarter step apart.
Contribution of frequency modulation to speech recognition in noise
Authors: Stickney Ginger S. , Nie Kaibao , Zeng Fan-Gang
Published: October 2005

Cochlear implants allow most patients with profound deafness to successfully communicate under optimal listening conditions. However, the amplitude modulation (AM) information provided by most implants is not sufficient for speech recognition in realistic settings where noise is typically present. This study added slowly varying frequency modulation (FM) to the existing algorithm of an implant simulation and used competing sentences to evaluate FM contributions to speech recognition in noise. Potential FM advantage was evaluated as a function of the number of spectral bands, FM depth, FM rate, and FM band distribution. Barring floor and ceiling effects, significant improvement was observed for all bands from 1 to 32 with the additional FM cue both in quiet and noise. Performance also improved with greater FM depth and rate, which might reflect resolved sidebands under the FM condition. Having FM present in low-frequency bands was more beneficial than in high-frequency bands, and only half of the bands required the presence of FM, regardless of position, to achieve performance similar to when all bands had the FM cue. These results provide insight into the relative contributions of AM and FM to speech communication and the potential advantage of incorporating FM for cochlear implant signal processing.
Reducing individual differences in the external-ear transfer functions of the Mongolian gerbil
Authors: Maki Katuhiro , Furukawa Shigeto
Published: October 2005

This study examines individual differences in the directional transfer functions (DTFs), the directional components of head-related transfer functions of gerbils, and seeks a method for reducing these differences. The difference between the DTFs of a given animal pair was quantified by the intersubject spectral difference (ISSD), which is the variance in the difference spectra of DTFs for frequencies between 5 and 45kHz and for 361 source directions. An attempt was made to reduce the ISSD by scaling the DTFs of one animal in frequency and/or rotating the DTFs along the source coordinate sphere. The ISSD was reduced by a median of 12% after optimal frequency scaling alone, by a median of 19% after optimal spatial rotation alone, and by a median of 36% after simultaneous frequency scaling and spatial rotation. The optimal scaling factor (OSF) and the optimal coordinate rotation (OCR) correlated strongly with differences in head width and pinna angles (i.e., pinna inclination around the vertical and front–back axes), respectively. Thus, linear equations were derived to estimate the OSF and OCR from these anatomical measurements. The ISSD could be reduced by a median of 22% based on the estimated OSF and OCR.
Ultrasonic guided wave monitoring of composite wing skin-to-spar bonded joints in aerospace structures
Authors: Matt Howard , Bartoli Ivan , Lanza di Scalea Francesco
Published: October 2005

The monitoring of adhesively bonded joints by ultrasonic guided waves is the general topic of this paper. Specifically, composite-to-composite joints representative of the wing skin-to-spar bonds of unmanned aerial vehicles (UAVs) are examined. This research is the first step towards the development of an on-board structural health monitoring system for UAV wings based on integrated ultrasonic sensors. The study investigates two different lay-ups for the wing skin and two different types of bond defects, namely poorly cured adhesive and disbonded interfaces. The assessment of bond state is based on monitoring the strength of transmission through the joints of selected guided modes. The wave propagation problem is studied numerically by a semi-analytical finite element method that accounts for viscoelastic damping, and experimentally by ultrasonic testing that uses small PZT disks preferably exciting and detecting the single-plate s0 mode. Both the models and the experiments confirm that the ultrasonic energy transmission through the joint is highly dependent on the bond conditions, with defected bonds resulting in increased transmission strength. Large sensitivity to the bond conditions is found at mode coupling points, as a result of the large interlayer energy transfer.
Holographic reconstruction of odd-shaped 3-D sources
Authors: Veronesi William A. , Maynard J. D.
Published: October 2005

As previously described [J. D. Maynard, J. Acoust. Soc. Am. Suppl. 174, S37 (1983)], nearfield acoustical holography can reconstruct the surface velocity and pressure over a level surface in a separable coordinate system from measusrements of the radiated pressure field over a parallel level surface. This study investigates the feasability of reconstructing the surface pressure and normal velocity over surfaces which do not conform to a level surface. Such a reconstruction involves numerically determining a distribution of surface pressure and velocity which satisfies the surface Helmholtz integral equation and which is consistent with the Helmholtz integral equation for the pressure field measured on the level surface. Details of the algorithm and results of computer simulations for a uniformly pulsating sphere and a piston set in a sphere (measurements simulated over a planar surface) are presented. [Work supported by ONR and NASA.]
Continuous multiword recognition performance of young and elderly listeners in ambient noise
Authors: Sato Hiroshi
Published: October 2005

Hearing threshold shift due to aging is known as a dominant factor to degrade speech recognition performance in noisy conditions. On the other hand, cognitive factors of aging-relating speech recognition performance in various speech-to-noise conditions are not well established. In this study, two kinds of speech test were performed to examine how working memory load relates to speech recognition performance. One is word recognition test with high-familiarity, four-syllable Japanese words (single-word test). In this test, each word was presented to listeners; the listeners were asked to write the word down on paper with enough time to answer. In the other test, five continuous word were presented to listeners and listeners were asked to write the word down after just five words were presented (multiword test). Both tests were done in various speech-to-noise ratios under 50-dBA Hoth spectrum noise with more than 50 young and elderly subjects. The results of two experiments suggest that (1) Hearing level is related to scores of both tests. (2) Scores of single-word test are well correlated with those of multiword test. (3) Scores of multiword test are not improved as speech-to-noise ratio improves in the condition where scores of single-word test reach their ceiling.