A new design method for a compound parabolic concentrator heat collector is described. The conventional design of the ideal compound parabolic concentrator collector has a touching point between a light absorber and the reflectors. This structure is not preferable from the standpoint of conductive heat leakage and thermal stress on ...

Whether temporal resolution in noisebursts is primarily determined by the highest frequency component in the signal or its absolute bandwidth remains unclear. In this study, the absolute bandwidths and upper cutoff frequencies of signal noisebursts were varied across broad frequency ranges, several times greater than previously jointly studied. The purpose ...

Temporal gap detection in bands of noise is a basic paradigm to investigate auditory temporal resolution. This study further examined the role of the long-term temporal organization for gap detection. Our experiments aimed at determining whether a gap superimposed on an amplitude-modulated noise was easier to detect when the amplitude ...

Frequency resolving power (FRP) was measured in normal humans using rippled noise with a phase-reversal test. The principle of the test was to find the highest ripple density at which an interchange of mutual peak and trough position (the phase reversal) in the rippled spectrum is detectable. In the frequency ...

Two experiments considered the behavior of subjects who cross gaps in a pathway without benefit of vision. The first experiment contrasted visually and nonvisually guided locomotion, finding a significantly greater number of refusals under nonvisual guidance but no loss of appropriate modulation of step components to the salient dimensions of ...

Experiment 1 examined the ability to compare relative level across frequency (profile analysis) for stimuli that were dynamically varying over time. The task was to detect an increment in level of a narrow band of noise (the target) in the presence or absence (reference condition) of four flanking bands (FBs). ...

Many listeners with severe-to-profound hearing losses perceive only a narrow range of low-frequency sounds and must rely on speechreading to supplement the impoverished auditory signal in speech recognition. Previous research with normal-hearing subjects [Grant et al., J. Exp. Psychol. 43A, 621-645 (1991)] demonstrated that speechreading was significantly improved when supplemented ...

Listeners' detection thresholds were measured for a 125-ms, 1-kHz tonal signal masked by a similarly gated 50-Hz-wide band of noise. A two-interval, adaptive, forced-choice procedure either with or without temporally surrounding cuing intervals containing 50-Hz-wide bands of noise was employed. When the cues were present, their center frequency was either ...

In this study, we introduce the wavelet transform (WT) as a method for characterizing the maturational changes in electrocortical activity in 24 fetal lambs ranging from 110-144 days gestation (term 145 days). The WT, based on multiresolution signal decomposition, is free of assumptions regarding the characteristics of the signal. The ...

We surveyed the dynamic visual acuity of 53 university athletes and 46 nonathlete university students, using a Landolt C ring as a target. The target moved from left to right on screen initially at the maximum angular velocity of 300 degrees/sec. and then gradually decreased in velocity until the subject ...

On the basis of a literature review, this work summarizes uterine animal and human electromyographic information obtained at cellular, myometrial, and abdominal levels during gestation and parturition. We show that both internal and external electromyograms occur in phase with intrauterine pressure increase and exhibit similar spectra, including a slow wave ...

Intratendinous metal markers were used to study gap formation in 36 flexor digitorum profundus repairs during and after early controlled motion with a programme combining dynamic traction and passive flexion to all four digits. The mean gap 3 weeks after operation was 2.5 mm. The mean final gap was 2.6 ...

This study provides a quantitative measure of the accuracy of the auditory periphery in representing prespecified time-frequency regions of initial and final diphones of spoken CVCs. The database comprised word pairs that span the speech space along Jakobson et al.'s binary phonemic features [Tech. Rep. No. 13, Acoustic Laboratory, MIT, ...

Purified light harvesting complexes I and II (LHI and LHII) from Rhodobacter capsulatus were purified and separately incorporated into liposomes. Electrochromic absorbance changes of bacteriochlorophyll bands in the proteoliposomes in response to K(+)-diffusion potentials were recorded. In LHII proteoliposomes the application of positive-inside potentials led to red shifts in the ...

The present research used a startle amplitude reduction paradigm to investigate the ability of the rat's auditory system to track rapidly changing acoustic transients. Specifically examined was the ability of brief gaps in otherwise continuous noise to reduce the amplitude of a subsequently elicited acoustic startle reflex. The duration of ...

The effectiveness of two types of tonal cues for reducing frequency uncertainty was studied in a tonal detection-in-noise task. Signals varied at random from trial to trial over the range 750-3000 Hz. The three conditions included: (1) maximum uncertainty in which there were no cues; (2) minimal uncertainty in which ...

Spectral shape discrimination for harmonic complexes with 100-, 200-, or 400-Hz fundamental was investigated in two sets of experiments. In the first set, the signal was an increment in a single component of an otherwise equal-amplitude complex. The results of these experiments showed nearly a 30-dB increase in thresholds as ...

Common amplitude modulation across frequency facilitates comodulation masking release (CMR) and may also contribute to auditory grouping. The purpose of the present investigation was to determine whether there is an association between these two phenomena; that is, does the occurrence of CMR require that the comodulated noise bands making up ...

The ability of listeners to "glimpse" acoustic cues during the quieter sections of an interrupted noise has primarily been studied using maskers with interruptions occurring simultaneously across the entire frequency range of the masker--broadband comodulated interruptions. Here, the possibility of uncomodulated glimpsing (the glimpsing of acoustic cues separated both in ...

Experiments 1 and 2 investigated the effect of frequency selectivity on comodulation masking release (CMR) in normal-hearing subjects, examining conditions where frequency selectivity was relatively good (low masker level at both low [500-Hz] and high [2500-Hz] signal frequency, and high masker level at low signal frequency) and where frequency selectivity ...

Thresholds for detecting a temporal gap in a 20-Hz-wide band of noise (the target) were measured for the target alone, and in the presence of multiple 20-Hz-wide flanking bands presented to the opposite ear. The flanking bands caused gap thresholds to increase, and this effect was greater at higher levels ...

We perfected the narrow spectral band fundus photographic system using interference filters at the wavelengths of 417, 478, 500, 530, 547, 570, 589, 607, 628 and 648 nm. Tests about the light penetration of filters and exposure of various brand films were made on this system. Studies of the contrast ...

The IR absorption frequencies as derived from second derivatives of the Fourier transform IR spectra of the amide I' bands of globular proteins in D2O are compared to those obtained from band fitting of the vibrational circular dichroism (VCD) spectra. The two sets of frequencies are in very good agreement, ...

Thresholds for the detection of gaps in sinusoidal signals were measured as a function of frequency (100-2000 Hz) and level (25-85 dB SPL) in 11 normally hearing subjects. The sinusoids were presented in a background noise intended to mask spectral splatter associated with the gap. In a separate experiment, auditory ...

This experiment examines the "strength" of auditory fusion for narrow-band noise pairs. Each pair of noise bands consisted of a target band and a flanker band presented simultaneously. The temporal envelopes of the noise bands within a pair fluctuated either in synchrony (synchronous condition) or not in synchrony (nonsynchronous condition). ...

Estimates of cochlear traveling wave velocity (TWV) were computed from derived band auditory brain-stem response (ABR) latencies in 24 normal-hearing subjects. Wave V latencies were determined for each of six derived frequency bands (unmasked-8 kHz, 8-4 kHz, 4-2 kHz, 2-1 kHz, 1 kHz-500 Hz, and 500-250 Hz). Representative frequencies were ...

Temporal gap detection thresholds were measured in narrow-band noise-burst markers having acoustic characteristics representative of isolated steady-state second-formant (F2) properties for/p,t,k/paired separately with/i,ae,u,o/. The results revealed that gap detection threshold increased systematically as the difference was increased between the simulated stop and vowel F2 frequencies. A strong positive correlation (r ...

Three subjects with unilateral cochlear hearing loss and three subjects with bilateral cochlear hearing loss were tested in three experiments. In the first, their auditory filter shapes were measured for center frequencies of 700 and 2000 Hz, using the notched-noise method. The auditory filters were generally broader for the impaired ...

The inherent fluctuations present in narrowbands of noise may limit the ability to detect gaps in the noise; 'dips' in the noise may be confused with the gap to be detected. For subjects with cochlear hearing loss, loudness recruitment may effectively magnify the fluctuations and this could partly account for ...

Monaural detection with a contralateral cue (MDCC) was measured with and without a 20-dB overall roving level to determine the contribution of loudness to performance on this task. Psychometric functions were obtained for three normal-hearing subjects as a function of the signal-to-noise ratio for pure-tone and 1/3-oct noiseband signals at ...

Head-related transfer functions for differently centered narrow noise bands were obtained on 6 subjects. Derived from these measurements were covert peak areas (CPAs), defined as the spatial constellation of loudspeakers that generates maximal sound pressure at the entrance of the ear canal for specific bands of frequency. On the basis ...

Measurements are reported on the detectability of signals added to narrow-band sounds. The narrow-band sounds had a bandwidth of 20 Hz and were either Gaussian noise with flat amplitude spectra or sets of equal-amplitude sinusoidal components whose phases were chosen at random. Four different kinds of sinusoidal signals were used. ...

The ability to detect changes in the spectral shape of narrow-band tonal complexes (spectral profiles) is examined. The standard consists of three tones of equal intensity; thresholds for detecting an increment in the level of the central, 1000-Hz tone are estimated. A roving-level procedure is used in order to impose ...

A three-interval, forced-choice procedure that obtained complete psychometric functions was used to study frequency discrimination for 13-item continua of impulse-generated, narrow-band, buzz-like, steady-state sounds. For all subjects and durations, discrimination relative to the highest center frequency (1060 Hz) stimuli was better than discrimination relative to the lowest center frequency (940 ...

Thresholds for the detection of temporal gaps in sinusoidal signals were measured as a function of frequency (100-2000 Hz) and level in 15 elderly hearing-impaired subjects and 11 elderly subjects with near-normal hearing at frequencies below 2000 Hz. The sinusoids were presented in a background noise intended to mask spectral ...

The effect of ear canal pressure variation (ECPV) on click evoked otoacoustic emissions (EOAEs) was compared to the suppressive effect observed with contralateral acoustic stimulation (CAS) in 11 healthy subjects. Both total EOAE amplitude and amplitude of 200 Hz frequency bands (22) were analyzed. Our results revealed that the ECPV ...

Masking sounds can be continuously present, gated simultaneously with the signal, or gated somewhat prior to the signal. This continuum of relative onset times was explored using waveforms of the sort commonly employed in studies of comodulation masking release (CMR). There was a 50-Hz masker band centered on the 1250-Hz ...

The ability to detect a 2000-Hz tone added to bands of noise centered at 2000 Hz was measured using a two-interval, forced-choice, pulsed-masker paradigm. The stimuli ranged in duration from 50-200 ms, and the maskers ranged in bandwidth from 5-320 Hz. In one condition, the bands of noise had equal ...

Intratendinous metal markers were used to study the formation of gaps in flexor digitorum profundus tendon repairs during and after early controlled motion with dynamic flexion traction and to evaluate their significance for results in 34 digits with repairs in zone II. The mean (+/- SD) final repair elongation was ...

The development of auditory temporal acuity during infancy was examined in 3-, 6-, and 12-month-old infants and in adults using the gap detection paradigm. Listeners detected a series of gaps, or silent intervals, or variable duration in a broadband noise. In order to vary the acoustic frequencies available to the ...

Outside of the laboratory, listening conditions are often less than ideal, and when attending to sounds from a particular source, portions are often obliterated by extraneous noises. However, listeners possess rather elegant reconstructive mechanisms. Restoration can be complete, so that missing segments are indistinguishable from those actually present and the ...

The masking level difference (MLD) is a psychoacoustic phenomenon derived from the subtraction of S pi No thresholds (signals pi radians out of phase and noise in phase at the two ears) from SoNo thresholds (signals and noise in phase at the two ears). The purpose of this study was ...

An ECG sampled at a rate of 500 samples s-1 or more produces a large amount of redundant data that are difficult to store and transmit. A process is therefore required to represent the signals with clinically acceptable fidelity and with the least code bits possible. In the paper, an ...

Temporal gap detection was measured as a function of absolute signal bandwidth at a low-, a mid-, and a high-frequency region in six listeners with normal hearing sensitivity. Gap detection threshold decreased monotonically with increasing stimulus bandwidth at each of the three frequency regions. Given conditions of equivalent absolute bandwidth, ...

The purpose of this study was to compare the role of frequency selectivity in measures of auditory and vibrotactile temporal resolution. In the first experiment, temporal modulation transfer functions for a sinusoidally amplitude modulated (SAM) 250-Hz carrier revealed auditory modulation thresholds significantly lower than corresponding vibrotactile modulation thresholds at SAM ...

The surface myoelectric (ME) signal from the vastus lateralis muscle was studied during ergocycling at various mechanical powers (MPs) and pedalling rates (PRs). The envelope of the signal was described using a power spectral density function estimate at very low frequency. A highly smoothed burst pattern was found independently at ...

The high-pass noise masking technique was used to obtain derived frequency-specific cochlear microphonics (CM) from subtracted waveforms to rarefaction and condensation stimuli recorded with a tympanic membrane electrode. Two characteristics suggest that the response is place-specific CM: the derived response retains the same frequency as the stimulating toneburst and the ...

The N(2)O infrared spectrum from 900 to 4700 cm(-1) has been studied with a high-resolution Fourier-transform spectrometer. Measurements were made of line frequencies of several N(2)O isotopes for several ground-state and hot bands. A few of these bands are being reported for the first time, to my knowledge: the 1530-0330, ...

This study sought to differentiate between the effect of stimulus bandwidth and the effect of number of activated auditory channels on gap detection in narrow bands of noise. The aim was to clarify the role of across-frequency analysis in temporal processing. Experiment 1 established that when total noise bandwidth is ...

In comodulation masking release (CMR), thresholds for a signal masked by a narrow-band noise are reduced when additional noise is present. To demonstrate CMR, the additional noise must have similar amplitude envelope fluctuations over time as the primary noise band masking the signal. The specific source of information that provides ...