Papers by Carrick Talmadge
arXiv (Cornell University), 1996
The suggestion in 1986 of a possible gravity-like ``fifth" fundamental force renewed interest in ... more The suggestion in 1986 of a possible gravity-like ``fifth" fundamental force renewed interest in the question of whether new macroscopic forces are present in nature. Such forces are predicted in many theories which unify gravity with the other known forces, and their presence can be detected by searching for apparent deviations from the predictions of Newtonian gravity. We review the phenomenology behind searches for a ``fifth force", and present a summary of the existing experimental constraints.
Geophysical Journal International, Jan 23, 2015
Journal of the Acoustical Society of America, Oct 1, 1992
I r urdn fr t,c n 0f ,nformatOn us etimated to peage .h Iar r nes1• . o n W d the tim for re.u• w... more I r urdn fr t,c n 0f ,nformatOn us etimated to peage .h Iar r nes1• . o n W d the tim for re.u• wMng. itrutti•On. ,earching exastang datae so ota. co~lletion of information. inluding tii ettios for r•eucing thus burden, to Wa0ntton Hadiquarters iervuas. 7ctO :f r information operation and ReportI. IIS Jetterbon Davis Hghway. Suite Q204. ingto, . V 222024302. a to the Office of Management and Budget. Paperwork Reducion Propeat (0704-011)S Waehington. DC 20503 1. AGENCY USE ONLY (Leave blank) 2. REPORT DATE
Auditory Mechanisms: Processes and Models, 2006
Geophysical Journal International, 2015
Typical infrasound propagation paths extend into the middle and upper atmosphere before turning b... more Typical infrasound propagation paths extend into the middle and upper atmosphere before turning back to Earth near the stratopause or lower thermosphere. The modelling of infrasound propagation is complicated by several factors. Propagation of sound in the atmosphere becomes increasingly non-linear as the mean density of the atmosphere decreases. As a consequence, infrasound propagation, which can follow paths high into the atmosphere before turning back to earth, is intrinsically non-linear. Further, attenuation of sound also increases as the mean density of the atmosphere decreases. Linear propagation modelling predicts severe attenuation along thermospheric paths, in contradiction with observation. Finally, the currently available atmospheric specifications necessarily involve temporal and spatial interpolations which can lead to the omission of atmospheric fluctuations to which infrasound propagation is sensitive. In this paper, existing methods for modelling weakly non-linear propagation are extended to account for the moving inhomogeneous medium and are then used to study the modelling of waveforms produced by impulsive events. It is found that there is a substantial interplay between signal attenuation and non-linear distortion. Waveform steepening and shocking in the middle and upper atmosphere associated with higher harmonic generation is moderated by attenuation while attenuation in the upper atmosphere is moderated by period lengthening associated with low frequency generation. The modelling of observed data is then considered. Using traveltime data, corrections to the atmospheric specifications are obtained. The predicted waveform evolution, modelled using the developed non-linear propagation model and the corrected atmospheric specifications, matches the observations well.
Physical Review Letters, 1988
New model-independent constraints on possible modifications of Newtonian gravity over solar-syste... more New model-independent constraints on possible modifications of Newtonian gravity over solar-system distance scales are presented and their implications discussed, The constraints arise from the analysis of various planetary astrometric data sets. The results of the model-independent analysis are then applied to set limits on a variation in the 1/r2 behavior of gravity, on possible Yukawa-type interactions with ranges of the order of planetary distance scales, and on a deviation from Newtonian gravity of the type discussed by Milgrom.
The Journal of the Acoustical Society of America, 2008
Distortion product otoacoustic emission (DPOAE) level from normal hearing individuals can vary by... more Distortion product otoacoustic emission (DPOAE) level from normal hearing individuals can vary by as much as 30dB with small frequency changes (a phenomenon known as DPOAE fine structure). This fine structure is hypothesized to stem from the interaction of components from two different regions of the cochlea (the nonlinear generator region and the reflection component from the DP region). An efficient procedure to separate these two components would improve the clinical and research utility of DPOAE by permitting separate evaluation of different cochlea regions. In this paper, two procedures for evaluating DPOAE fine structure are compared: DPOAE generated by fixed-frequency primaries versus continuously sweeping primaries. The sweep DPOAE data are analyzed with a least squares fit filter. Sweep rates of greater than 8s per octave permit rapid evaluation of the cochlear fine structure. A higher sweep rate of 2s per octave provided DPOAE without fine structure. Under these conditions...
The Journal of the Acoustical Society of America, 2007
Originally proposed as a method for measuring the power gain of the cochlear amplifier, Allen–Fah... more Originally proposed as a method for measuring the power gain of the cochlear amplifier, Allen–Fahey experiments compare intracochlear distortion products and ear-canal otoacoustic emissions (OAEs) under tightly controlled conditions. In this paper Allen–Fahey experiments are shown to place significant constraints on the dominant mode of reverse energy propagation within the cochlea. Existing Allen–Fahey experiments are reviewed and shown to contradict the predictions of compression-wave OAE models recently proposed in the literature. In compression-wave models, distortion products propagate from their site of generation to the stapes via longitudinal compression waves in the cochlear fluids (fast waves); in transverse traveling-wave models, by contrast, distortion products propagate primarily via pressure-difference waves whose velocity and other characteristics depend on the mechanical properties of the cochlear partition (slow waves). Compression-wave models predict that the disto...
The Journal of the Acoustical Society of America, 1994
Some knowledge about the transmission characteristics of the human middle ear may be obtained by ... more Some knowledge about the transmission characteristics of the human middle ear may be obtained by comparing ear canal levels of external tones and spontaneous emissions of the same frequency, which when used with another tone give similar ear canal levels of distortion product otoacoustic emissions. It is assumed that the cochlear activity patterns of an external tone of frequency f2 and a spontaneous emission of frequency f2, which produce the same levels of ear canal cubic distortion products when used in conjunction with an external tone of frequency f1 and fixed level, are very similar. The degree of similarity is studied using nonlinear active cochlear models that give spontaneous emissions [Talmadge and Tubis (1993)]. The relationship of the cochlear activities at the place of peak excitation and at the base of the cochlea is also studied in detail. The model results indicate that the comparison of ear canal levels of external tones and spontaneous emissions, which are equivale...
The Journal of the Acoustical Society of America, 1992
Previous investigations of the time constants associated with suppression and recovery from suppr... more Previous investigations of the time constants associated with suppression and recovery from suppression of spontaneous otoacoustic emissions (SOAEs) by pulsed external tones have shown that limit-cycle-oscillator models of SOAEs provide a basis for qualitative and quantitative interpretation of SOAE behavior [Talmadge et al., Mechanics and Biophysics of Hearing, edited by P. Dallos et al., pp. 235–242 (1990)]. The Van der Pol limit-cycle oscillator model is generalized to the case of two external driving tones, one continuous and the other pulsed. The continuous tone introduces a suppressed SOAE amplitude that is further modulated by the pulsed suppressor component. The model predicts that suppression onset and recovery times will increase with increases in the amount of suppression from the continuous suppressor tone. Preliminary data indicate that the onset and recovery times are affected in the manner implied by the model. [Work supported by NIH-NIDCD Grant No. DC 00307.]
The Journal of the Acoustical Society of America, 2000
Distortion-product-otoacoustic-emission (DPOAE) phase-versus-frequency functions and correspondin... more Distortion-product-otoacoustic-emission (DPOAE) phase-versus-frequency functions and corresponding phase-gradient delays have received considerable attention because of their potential for providing information about mechanisms of emission generation, cochlear wave latencies, and characteristics of cochlear tuning. The three measurement paradigms in common use (fixed-f1, fixed-f2, and fixed-f2/f1) yield significantly different delays, suggesting that they depend on qualitatively different aspects of cochlear mechanics. In this paper, theory and experiment are combined to demonstrate that simple phenomenological arguments, which make no detailed mechanistic assumptions concerning the underlying cochlear mechanics, predict relationships among the delays that are in good quantitative agreement with experimental data obtained in guinea pigs. To understand deviations between the simple theory and experiment, a general equation is found that relates the three delays for any deterministic ...
The Journal of the Acoustical Society of America, 1999
High-resolution measurements of distortion product otoacoustic emissions (DPOAEs) from three diff... more High-resolution measurements of distortion product otoacoustic emissions (DPOAEs) from three different experimental paradigms are shown to be in agreement with the implications of a realistic “two-source” cochlear model of DPOAE fine structure. The measurements of DPOAE amplitude and phase imply an interference phenomenon involving one source in the region of strong nonlinear interaction of the primary waves (the strong “overlap” or generation region), and the other source region around the DPOAE tonotopic place. The component from the DPOAE place can be larger than the one from the generator region. These findings are supported by the analysis of the onset and offset of the DPOAE when the higher-frequency primary is pulsed on and off. The two-source hypothesis was further tested by adding a third tone closer in frequency to the DPOAE which modifies the amplitude of the component from the DPOAE place and leaves the one from the generator region unchanged. The results agree well with...
The Journal of the Acoustical Society of America, 2005
A detailed measurement of distortion product otoacoustic emission (DPOAE) fine structure was used... more A detailed measurement of distortion product otoacoustic emission (DPOAE) fine structure was used to extract estimates of the two major components believed to contribute to the overall DPOAE level in the ear canal. A fixed-ratio paradigm was used to record DPOAE fine structure from three normal-hearing ears over a range of 400 Hz for 12 different stimulus-frequency ratios between 1.053 and 1.36 and stimulus levels between 45 and 75 dB SPL. Inverse Fourier transforms of the amplitude and phase data were filtered to extract the early component from the generator region of maximum stimulus overlap and the later component reflected from the characteristic frequency region of the DPOAE. After filtering, the data were returned to the frequency domain to evaluate the impact of the stimulus-frequency ratio and stimulus level on the relative levels of the components. Although there were significant differences between data from different ears some consistent patterns could be detected. The c...
The Journal of the Acoustical Society of America, 1993
DPOAEs generated by the interaction of one external tone and one spontaneous otoacoustic emission... more DPOAEs generated by the interaction of one external tone and one spontaneous otoacoustic emission (SOAE) are maximal when the external stimulus begins to suppress the level of the emission. Consequently, investigations of the f2/f1 and L2/L1 ratios producing maximum distortion are limited. DPOAEs generated in this way were systematically compared to DPOAEs generated by two external tones. First, another external tone with the same frequency as the SOAE was inserted into the ear canal to entrain the spontaneous emission and maintain a known signal at the frequency of the spontaneous emission. Second, DPOAEs generated by two external tones with same frequency and level ranges as above were measured in ears with no spontaneous emissions in the frequency range examined. The pattern of maximum DPOAEs are interpreted in terms of the excitation patterns of external tones and SOAEs on the basilar membrane.
The Journal of the Acoustical Society of America, 2013
Otoacoustic emissions (OAEs), a sensitive measure of cochlear processing, may be altered by subtl... more Otoacoustic emissions (OAEs), a sensitive measure of cochlear processing, may be altered by subtle changes in auditory function that are not measureable by usual clinical methods. We studied auditory function in carriers of genetic mutations related to recessive hereditary hearing loss where we hypothesized that carrying a single mutated copy may compromise auditory function and be reflected when sensitive assays are used. Parents who were confirmed carriers of recessive mutations associated with GJB2 (connexin 26) and obligate carriers of mutations related to recessive hearing loss not related to GJB2 mutations were compared to age and gender matched control subjects. All participants had normal pure tone and middle ear responses. Metrics included transient evoked OAEs and distortion product OAE fine structure. DPOAE fine structure was specifically explored based on the ability to isolate components that could be differentially affected by genetic mutations. The results support the hypothesis that carriers of gene mutations related to hearing loss display subtle auditory abnormalities that can be observed in OAEs. These findings will be related to other studies of subtle changes in OAEs in disorders affecting auditory function. [Supported by NIH NIDCD R01-DC03679 and VU Development Funds] Published by the Acoustical Society of America through the American Institute of Physics Hood et al.
The Journal of the Acoustical Society of America, 1990
Limit-cycle-oscillator models of spontaneous otoacoustic emissions have been used to provide qual... more Limit-cycle-oscillator models of spontaneous otoacoustic emissions have been used to provide qualitative descriptions of the interactions of spontaneous emissions with external tones and their response to aspirin administration. The parameters of several classes of such models are estimated from data on the relaxation dynamics of spontaneous emissions, associated with the onset of, and recovery from, suppression by external tones. Aspirin administration is used to control the emission levels, with the relaxation time being observed to increase with decreasing emission level. The models considered include a modified Van der Pol oscillator, with the possibility of linear passive damping in the limit of large displacements, and an oscillator with nonlinear time-delayed elasticity. [Work supported by NIDCD.]
The Journal of the Acoustical Society of America, 2006
The near-ground behavior of the low-frequency (100Hzto500Hz) sound field in the nocturnal sound d... more The near-ground behavior of the low-frequency (100Hzto500Hz) sound field in the nocturnal sound duct is studied theoretically and experimentally. In the first few meters of the atmosphere, narrow-band sound fields are found to have a characteristic vertical structure. The sound field is the superposition of a “surface mode,” whose magnitude decreases monotonically with altitude, with a sum of “higher modes,” each of whose magnitudes has a pronounced minimum a few meters from the ground at approximately the same height. The surface mode attenuates to negligible levels after a few hundred meters from the source. Consequently, more than a few hundred meters from a narrow-band source, there is a “quiet height” at which the sound level is reduced by 10to15dB relative to its value on the ground. The narrow-band quiet height is shown to be a robust feature of nocturnal sound propagation.
The Journal of the Acoustical Society of America, 2008
Otoacoustic emissions (OAE) are frequency dispersive (different frequencies have different latenc... more Otoacoustic emissions (OAE) are frequency dispersive (different frequencies have different latencies), because of the properties of the basilar membrane. These frequency-dependent latency differences, are used to separate the transient otoacoustic emissions (TEOAE) from the stimulus, but have not been used with stimulus frequency (SFOAE) and distortion product (DPOAE) otoacoustic emissions. If continuously-sweeping tones are used to generate DPOAE and SFOAE, the frequency dispersive properties of these OAE cannot only be used to separate the evoking stimuli from the OAE, but also to separate OAE coming from different cochlear regions. Modifications of the LSF procedure to extract OAE (Long &Talmadge, 1997: JASA, 102:2831-2848; Talmadge et al. 1999: JASA,105:275-292) permit not only the extraction of the different OAE components, but also provide an estimate of the latency of the OAE, which does not depend on group delay. DPOAE and SFOAE extracted using sweeping tones in normal and i...
The Journal of the Acoustical Society of America, 2008
Coherent-reflection theory explains the generation of stimulus-frequency and transient-evoked oto... more Coherent-reflection theory explains the generation of stimulus-frequency and transient-evoked otoacoustic emissions by showing how they emerge from the coherent “backscattering” of forward-traveling waves by mechanical irregularities in the cochlear partition. Recent published measurements of stimulus-frequency otoacoustic emissions (SFOAEs) and estimates of near-threshold basilar-membrane (BM) responses derived from Wiener-kernel analysis of auditory-nerve responses allow for comprehensive tests of the theory in chinchilla. Model predictions are based on: (1) an approximate analytic expression for the SFOAE signal in terms of the BM traveling wave and its complex wave number; (2) an inversion procedure that derives the wave number from BM traveling waves; and (3) estimates of BM traveling waves obtained from the Wiener-kernel data and local scaling assumptions. At frequencies above 4 kHz, predicted median SFOAE phase-gradient delays are in excellent agreement with the SFOAE measure...
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Papers by Carrick Talmadge