Modulation gap detection (MGD) is a procedure that measures the sensitivity to an interruption in the modulation pattern imposed upon one or more carrier frequencies. The MGD task was developed to test conditions where a temporal event traverses frequency, but without a concomitant interruption in the spectral continuity of the ...

Human vision can detect spatiotemporal information conveyed by first-order modulations of luminance and by second-order, non-Fourier modulations of image contrast. Models for second-order motion have suggested two filtering stages separated by a rectifying nonlinearity. We explore here the encoding of stationary first-order and second-order gratings, and their interaction. Stimuli consisted ...

This study examined whether "modulation masking" could be produced by temporal similarity of the probe and masker envelopes, even when the masker envelope did not contain a spectral component close to the probe frequency. Both masker and probe amplitude modulation were applied to a single 4-kHz sinusoidal or narrow-band noise ...

Evidence from power spectra of deep-sea oxygen isotope time series suggests that the climate system of Earth responds nonlinearly to astronomical forcing by frequency modulating eccentricity-related variations in insolation. With the help of a simple model, it is shown that frequency modulation of the approximate 100,000-year eccentricity cycles by the ...

In this paper acoustic evidence is presented for the presence of amplitude modulation in budgerigar (Melopsittacus undulatus) contact calls and learned English vocalizations. Previously, acoustic analyses of budgerigar vocalizations have consisted solely of visual inspection of spectrograms or power spectra (derived from Fourier transformation). Such analyses have led researchers to ...

Intensity modulated radiation therapy may be delivered via dynamic control of a multileaf collimator by defining dynamic leaf trajectories at a series of control points which are spaced at arbitrary intervals throughout an exposure. Leaves move linearly between the positions defined at the control points and hence leaf motion is ...

Iterated rippled noise (IRN) produces a pitch corresponding to the IRN delay. The pitch persists even when the sound is high-pass filtered at 12 times the reciprocal of the IRN delay, i.e., in the absence of resolved spectral peaks. Typically, when a sound produces a pitch in the absence of ...

To be fed, a king penguin, Aptenodytes patagonicus, chick must identify the call of its parents, in the continuous background noise of the colony. To study this recognition process, we played back to the chicks parental calls with acoustic parameters modified in the temporal and frequency domains. The parental call ...

The algorithm for the control of the jamming avoidance response (JAR) of Eigenmannia has been the subject of debate for over two decades. Two competing theories have been proposed to explain how fish determine the correct direction to shift their pacemaker frequency during jamming. One theory emphasizes the role of ...

Loudness matches were obtained between unmodulated carriers and carriers that were amplitude modulated either periodically (rates between 2 and 32 Hz, modulation sinusoidal either on a linear amplitude scale or on a dB scale; the latter is called dB modulation) or with the envelope of the speech of a single ...

The torsional eye movements elicited by sinusoidal galvanic vestibular stimulation (GVS) (0.012-3.13 Hz) were examined in healthy humans. GVS consistently induced sinusoidal modulation of the torsional slow phase velocity (SPV), which was linearly related to stimulus intensity. At low frequencies (< 0.1 Hz) nystagmic responses could be discriminated from an ...

We measured the modulation transfer function for microjetted microlenses with diameters ranging between 109 and 400 mum and with focal lengths ranging between 135 and 540 mum. We found that single-drop 109-mum-diameter microlenses perform close to their theoretical cutoff frequency. However, the larger lenses made with multiple droplets have a ...

The propagation of a weak light beam through a quantum well in the vicinity of an excitonic resonance that is modulated harmonically in time at terahertz frequency is considered. It is found that the reflection probability of the light beam is considerably different in the cases of purely coherent versus ...

Modulation frequency and orientation tuning of second-order mechanisms underlying the detection of modulation in local spatial-frequency information are assessed by using an oblique-masking paradigm. Stimuli were Gabor-filtered noise patterns in which the local carrier spatial frequency was modulated about an average value of 4.7 cycles per degree (cpd) according to ...

Estimates of temporal acuity under comparable conditions at low- and high-audio frequencies are rare. The present study used the amplitude-modulation detection paradigm to estimate temporal acuity over a range of audio frequencies from 800 to 12,800 Hz. Amplitude-modulation detection was measured as a function of modulation frequency for bandlimited noise ...

The functional development of the auditory system across metamorphosis was examined by recording neural activity from the torus semicircularis of larval and postmetamorphic bullfrog froglets in response to amplitude-modulated sound. Multiunit activity in the torus semicircularis during early larval stages showed significant phase-locking to the envelopes of amplitude-modulated noise bursts, ...

It is well established that low-level broad band noise can elicit an amplitude decrease in evoked otoacoustic emissions recorded in the opposite ear. However, the influence of the temporal characteristics of the contralateral stimulus on this effect remains largely unknown. In the present study, otoacoustic emissions evoked by 60 dB ...

We have studied the synaptic responses in hippocampal slices to stimulus patterns derived from in vivo recordings of place cell firing in a behaving rodent. We find that synaptic strength is strongly modulated during the presentation of these natural stimulus trains, varying 2-fold or more because of short-term plasticity. This ...

A theory is provided for the detection efficiency of diffuse light whose frequency is modulated by an acoustical wave. We derive expressions for the speckle pattern of the modulated light, as well as an expression for the signal-to-noise ratio for the detector. The aim is to develop a new imaging ...

A fast ferroelectric liquid-crystal spatial light modulator, originally developed for optical computing, has found a new application in vibrometry. A new scheme of vibration-synchronized double-exposure holographic interferometry is proposed that makes full use of the speed of the ferroelectric liquid-crystal spatial light modulator. Preliminary experiments were performed that demonstrate virtually ...

Acousto-optic (AO) devices are important spatial light modulators. They can be used as light-beam deflectors, rf true-time-delay lines, etc. To increase their spur-free dynamic range, we present what to our knowledge is a novel multichannel AO device structure, in which different channels have different carrier frequencies, so a wideband signal ...

We present a multiple-input, single-output, weakly nonlinear model of spatial light modulators by use of a second-order Volterra series and describe an experimental method to measure the nonlinear transfer functions by means of sinusoidal perturbation and synchronous detection with a lock-in amplifier. We also present an application of this method ...

The detectability of sinusoidal amplitude modulation at unexpected modulation rates was assessed using a probe-signal method. With this method, three listeners were led to expect a target modulation rate (4, 32, or 256 Hz) by presenting the signal most often at that rate, and sensitivity to modulation at six other ...

Behavioral and electrophysiological experiments were conducted to examine whether frequency-modulated electrocommunication signals are detected by the ampullary electroreceptor system in Eigenmannia. First, frequency-modulated electric organ discharges were found to contain a low-frequency component that could be detected by the ampullary system. Second, fish were successfully trained to distinguish a frequency-modulated ...

Preliminary investigations have been made in normally hearing alert adults to establish whether the 40 Hz modulation-following response (MFR) can be used to predict 400 Hz uncomfortable loudness levels (ULLs). The MFR stimulus was a 400 Hz carrier, amplitude- and frequency-modulated by a 40 Hz sine function. Subjective ULLs were ...

Relative modulation transfer is defined as contrast sensitivity under blur normalised to contrast sensitivity at optimum focus. Measured relative modulation transfer exceeds relative modulation transfer as calculated for aberration free optics at higher spatial frequencies (> 2 cpd). The contribution of spherical aberration to this discrepancy was studied. In the ...

In the first experiment, two measurements were compared--sensitivity to across-frequency changes in level and sensitivity to across-frequency changes in the modulation phase of SAM tones. For the level task, multi-tone stimuli composed of 2-80 tones ranging in frequency from 200 to 5000 Hz were used. For the phase task, the ...

This article reviews experimental data providing evidence on the effects of modulated electromagnetic fields of 30-120 V/m with a carrier frequency of 30 MHz modulated sinusoidally at frequencies of 2-50 Hz on the emotional responses accompanying various stages in the systems organization of behavior in rats. The blocking effects of ...

Vocalizations often have periodic variations of their acoustic waveform envelope. Two simultaneously presented frequencies have an envelope fluctuation with a frequency equal to their difference tone (DT = F2-F1). Sinusoidal amplitude modulation (SAM) of a carrier frequency also produces an envelope fluctuation. Electrical ensemble responses to DT and SAM stimuli ...

When a temporally fluctuating background is rapidly modulated (e.g. 30 Hz), the threshold variation of a superimposed flash (the probe) is approximately sinusoidal and in phase with the stimulus. But, with low rates of sinusoidal modulation (e.g. 1 Hz), the threshold variation is distinctly nonsinusoidal in shape. The bases of ...

These experiments examine the influence of excitation-pattern cues and temporal-fine-structure cues on frequency difference limens (FDLs) measured as a function of duration. In the first three conditions, listeners were required to detect a change in carrier frequency from a baseline of 250 or 2000 Hz, for stimuli with half-amplitude durations ...

Modulation detection and modulation rate discrimination thresholds were obtained at three different modulation rates (fm = 80, 160, and 320 Hz) and for three different ranges of modulation depths (m): full (100%), mid (70%-80%), and low (40%-60%) with both normal-hearing (NH) and hearing-impaired (HI) subjects. The results showed that modulation ...

Detailed measurement of the neural response to flicker frequency using functional MRI (fMRI) were made. The fMRI signal peaks at a flicker frequency of 8 Hz in human V1, in agreement with previous positron emission tomography (PET) and fMRI experiments. The modulation amplitude of the hemodynamic response to varying continuous ...

A new spatial light modulator that uses the electroabsorption and the electro-optic effects in a GaAs single crystal is proposed. The device has the same structure as a Pockels readout optical modulator and can be operated at a frame rate higher than 500 Hz. When the electroabsorption and the electro-optic ...

The aim of this study was to determine whether detection thresholds for amplitude modulated signals on a single electrode were influenced by a masking modulation on a second electrode in cochlear implant users. Data were collected from four post-linguistically deafened subjects using the Cochlear Limited prosthesis. Investigated were the effects ...

We demonstrate speckle photography using an optically addressed multiple quantum well spatial light modulator. An optical Fourier transform is used to allow real-time displacement measurements.

Interaural-delay sensitivity to high-frequency (> or = 3 kHz) sinusoidal-frequency-modulated (SFM) tones is examined for rates from 25 to 800 Hz and depths of -12 to 18 dB. Comparison is made to thresholds obtained for sinusoidal-amplitude-modulated (SAM) tones for the same observers and modulation rates. Both SAM and SFM threshold-by-rate ...

The unblended ozone line at 1044.533 cm(-1) was acquired by using the frequency modulation technique. A tunable CO(2) sideband laser with a GaAs waveguide modulator with a tuning bandwidth of 20 GHz in the mid-infrared region was used for this sideband at 1-MHz frequency with a peak-to-peak amplitude of 1 ...

We report a perceptual phenomenon that originates from a nonlinear operation during the visual process, and we use these observations to study the functional organization of the responsible nonlinearity; the regulation of visual sensitivity to light. When the contrast of a high frequency grating was modulated while its spatial and ...

In order to test the sensitivity of the human medial olivocochlear bundle (MOCB) to stimulus frequency fluctuations, changes in transient-evoked otoacoustic emission (TEOAE) amplitude induced by frequency modulated (FM) tones were measured in 18 normal-hearing subjects. The results revealed that TEOAE amplitude was reduced by contralateral FM tones at 40 ...

Discrimination of the direction of linearly frequency-modulated tones (FMs) was investigated in adult Mongolian gerbils (Meriones unguiculatus) using a footshock motivated shuttle box avoidance go/no go procedure. Symmetric pairs of FMs with frequency linearly increasing with time (ascending FMs) and with frequency linearly decreasing with time (descending FMs) were used ...

Steady-state responses evoked by simultaneously presented amplitude-modulated tones were measured by examining the spectral components in the recording that corresponded to the different modulation frequencies. When using modulation frequencies between 70 and 110 Hz and an intensity of 60 dB SPL, there were significant interactions between two stimuli when the ...

Electrophysiological studies in mammal primary auditory cortex have demonstrated neuronal tuning and cortical spatial organization based upon spectral and temporal qualities of the stimulus including: its frequency, intensity, amplitude modulation and frequency modulation. Although communication and other behaviourally relevant sounds are usually complex, most response characterizations have used tonal stimuli. ...

In five normally hearing subjects and seven subjects with damaged cochleas, detection thresholds for sinusoidal frequency modulation (FM) and amplitude modulation (AM) were measured using 1 s stimuli with a 500 Hz carrier frequency (Fc) at a 'comfortable' loudness (given by subject-dependent SPLs and SLs). The modulation frequency (Fmod) was ...

Binaural cues for spatial localization of complex high-frequency sounds are interaural level and time differences (ILDs and ITDs). We previously showed that cells in the lateral superior olive (LSO) are sensitive to ITDs in the envelope of sinusoidally amplitude-modulated (AM) signals up to a modulation frequency of only approximately 800 ...

Semispherical high-intensity light-emitting diodes (LEDS) mounted on a circuit board have been developed and examined for plant growth applications. This type of LED configuration, however, has problems such as relatively poor heat dissipation, difficulty of effecting high light uniformity, and high cost of assembly. Such problems may now be obviated ...

Neurons in the inferior colliculus (IC) of the awake big brown bat, Eptesicus fuscus, were examined for joint frequency and latency response properties which could register the timing of the bat's frequency-modulated (FM) biosonar echoes. Best frequencies (BFs) range from 10 kHz to 100 kHz with 50% tuning widths mostly ...

This work extends previous studies on the perceptual asymmetry between the local maxima and minima of wide frequency modulations (FMs) [L. Demany and K. I. McAnally, J. Acoust. Soc. Am. 96, 706-715 (1994); L. Demany and S. Clément, J. Acoust. Soc. Am. 97, 2454-2459 (1995); L. Demany and S. Clément, ...

The current study was designed to investigate the clinical application of amplitude modulation following response (AMFR) in cochlear implant candidates. A new digital signal processor (DSP)-assisted PC-based hardware and software was developed to perform both simultaneous generation of amplitude-modulated stimuli and the recording, and synchronized signal processing of the electrode ...

An anomalous photovoltaic film formed by simultaneous oblique sputter deposition of CdTe and CdS from different directions was integrated onto LiNbO(3) and combined with a Mach-Zehnder-type interferometric waveguide modulator. Irradiation by 830-nm laser light with low intensity near 1 mW of the photovoltaic film induced anomalous photovoltages of ~5 V, ...