Gap Duration Research Articles

Acoustical resonant absorption of pulsed laser radiation by a spherical absorber

We investigate the thermomechanical response of a spherical absorber to pulsed laser radiation and the potential for causing damage to the absorber and the surrounding material due to shockwave and bubble formation. We calculate the expected response of a spherical absorber to a series of laser pulses as a function of the gap duration between the pulses. We model two common absorbers that have different characteristics: a 1 μm melanosome found in the retina, and a 100 nm gold particle. We find that the thermomechanical response strongly depends on the duration between pulses and displays resonant effects with a characteristic period that depends on the absorber properties. This allows tuning the duration between pulses to channel a greater or lesser fraction of the absorbed energy into shockfront and bubble production, presenting various possibilities such as delivering large amounts of laser energy to produce strong thermal effects while suppressing unwanted pressure effects in the surrounding material. Resonance can also be used to target absorbers of a specific size, allowing generation of shockfronts in localized target regions to destroy specific cells. This specificity can also be used to sort particles by size.

Cortical evoked response to gaps in noise: within-channel and across-channel conditions.

The objective of this study was to describe the cortical evoked response to silent gaps in a group of young adults with normal hearing using stimulus conditions identical to those used in psychophysical studies of gap detection. Specifically, we sought to examine the P1-N1-P2 auditory evoked response to the onsets of stimuli (markers) defining a silent gap for within-channel (spectrally identical markers) and across-channel (spectrally different markers) conditions using four perceptually-equated gap durations. It was hypothesized that (1) P1, N1, and P2 would be present and consistent for 1st marker (before the gap) onsets; (2) for within-channel markers, P1, N1, and P2 would be present for 2nd marker (after the gap) onsets only when the gap was of a duration equal to or larger than the behaviorally measured gap detection threshold; and (3) for the across-channel conditions, P1, N1, and P2 would be present for 2nd marker onsets regardless of gap duration. This is expected due to the additional cue of frequency change following the gap. Twelve young adults (mean age 26 years) with normal hearing participated. Within-channel and across-channel gap detection thresholds were determined using an adaptive psychophysical procedure. Next, cortical auditory evoked potentials (P1-N1-P2) were recorded with a 32-channel Neuroscan electroencephalogram system using within-channel and across-channel markers identical to those used for the psychophysical task and four perceptually weighted gap durations: (1) individual listener's gap detection threshold; (2) above gap detection threshold; (3) below gap detection threshold; and (4) a 1-ms gap identical to the gap in the standard interval of the psychophysical task. P1-N1-P2 peak latencies and amplitudes were analyzed using repeated-measures analyses of variance. A temporal-spatial principal component analysis was also conducted. The latency of P2 and the amplitude of P1, N1, and P2 were significantly affected by the acoustic characteristics of the 2nd marker as well as the duration of the gap. Larger amplitudes and shorter latencies were generally found for the conditions in which the acoustic cues were most salient (e.g., across-channel markers, 1st markers, large gap durations). Interestingly, the temporal-spatial principal component analysis revealed activity elicited by gap durations equal to gap detection threshold in the latency regions of 167 and 183 ms for temporal-parietal and right-frontal spatial locations. The cortical response to a silent gap is unique to specific marker characteristics and gap durations among young adults with normal hearing. Specifically, when the onset of the 2nd marker is perceptually salient, the amplitude of the P1-N1-P2 response is relatively larger and the P2 latency is relatively shorter than for nonsalient 2nd marker onsets, providing noninvasive, nonbehavioral indicators of the neural coding of this important temporal cue in the thalamic-cortical region of the central auditory system. Gap duration appears to be most clearly indicated by P1 and T-complex amplitude.

Within- and across-channel gap detection in cochlear implant listeners

This study examined within- and across-electrode-channel processing of temporal gaps in successful users of MED-EL COMBI 40+ cochlear implants. The first experiment tested across-ear gap duration discrimination (GDD) in four listeners with bilateral implants. The results demonstrated that across-ear GDD thresholds are elevated relative to monaural, within-electrode-channel thresholds; the size of the threshold shift was approximately the same as for monaural, across-electrode-channel configurations. Experiment 1 also demonstrated a decline in GDD performance for channel-asymmetric markers. The second experiment tested the effect of envelope fluctuation on gap detection (GD) for monaural markers carried on a single electrode channel. Results from five cochlear implant listeners indicated that envelopes associated with 50-Hz wide bands of noise resulted in poorer GD thresholds than envelopes associated with 300-Hz wide bands of noise. In both cases GD thresholds improved when envelope fluctuations were compressed by an exponent of 0.2. The results of both experiments parallel those found for acoustic hearing, therefore suggesting that temporal processing of gaps is largely limited by factors central to the cochlea.

Encoding of temporal features of auditory stimuli in the medial nucleus of the trapezoid body and superior paraolivary nucleus of the rat

Neurons in the superior paraolivary nucleus (SPON) of the rat respond to the offset of pure tones with a brief burst of spikes. Medial nucleus of the trapezoid body (MNTB) neurons, which inhibit the SPON, produce a sustained pure tone response followed by an offset response characterized by a period of suppressed spontaneous activity. This MNTB offset response is duration dependent and critical to the formation of SPON offset spikes [Kadner A, Kulesza RJ Jr, Berrebi AS (2006) Neurons in the medial nucleus of the trapezoid body and superior paraolivary nucleus of the rat may play a role in sound duration coding. J Neurophysiol. 95:1499–1508; Kulesza RJ Jr, Kadner A, Berrebi AS (2007) Distinct roles for glycine and GABA in shaping the response properties of neurons in the superior paraolivary nucleus of the rat. J Neurophysiol 97:1610–1620]. Here we examine the temporal resolution of the rat's MNTB/SPON circuit by assessing its capability to i) detect gaps in tones, and ii) synchronize to sinusoidally amplitude modulated (SAM) tones. Gap detection was tested by presenting two identical pure tone markers interrupted by gaps ranging from 0 to 25 ms duration. SPON neurons responded to the offset of the leading marker even when the two markers were separated only by their ramps (i.e. a 0 ms gap); longer gap durations elicited progressively larger responses. MNTB neurons produced an offset response at gap durations of 2 ms or longer, with a subset of neurons responding to 0 ms gaps. SAM tone stimuli used the unit's characteristic frequency as a carrier, and modulation rates ranged from 40 to 1160 Hz. MNTB neurons synchronized to modulation rates up to ∼1 kHz, whereas spiking of SPON neurons decreased sharply at modulation rates ≥400 Hz. Modulation transfer functions based on spike count were all-pass for MNTB neurons and low-pass for SPON neurons; the modulation transfer functions based on vector strength were low-pass for both nuclei, with a steeper cutoff for SPON neurons. Thus, the MNTB/SPON circuit encodes episodes of low stimulus energy, such as gaps in pure tones and troughs in amplitude modulated tones. The output of this circuit consists of brief SPON spiking episodes; their potential effects on the auditory midbrain and forebrain are discussed.

Effect of tactile stimulus frequency on time perception: the role of working memory

In most models of interval timing, there is a central clock, which is considered to be highly protected from the effects of external stimuli. However, many studies have reported such effects and different theories are proposed to explain the observations. These include the effect of arousal, attention sharing, memory load and information processing on central clock as well as change in the speed of the pacemaker. In this study, we used regular vibrotactile stimuli with different frequencies in a "duration reproduction task" to investigate the effect of stimulus content on interval timing. Results showed that subjects overestimated the duration as a function of test stimulus frequency. A significant correlation between increasing the test frequency and overestimation of subjective time was observed. We further investigated the effect of blank and filled gaps with various durations on time estimation. Analysis revealed that regardless of gap duration, subjective time increased in the filled gap condition, compared to the blank gap. This effect was independent from contextual stimuli and correlated to the mean number of stimuli during the temporal interval rather than rate of stimulus presentation.

Hemispheric asymmetries for temporal information processing: Transient detection versus sustained monitoring

This study investigated functional differences in the processing of visual temporal information between the left and right hemispheres (LH and RH). Participants indicated whether or not a checkerboard pattern contained a temporal gap lasting between 10 and 40 ms. When the stimulus contained a temporal signal (i.e. a gap), responses were more accurate for the right visual field-left hemisphere (RVF-LH) than for the left visual field-right hemisphere (LVF-RH). This RVF-LH advantage was larger for the shorter gap durations (Experiments 1 and 2), suggesting that the LH has finer temporal resolution than the RH, and is efficient for transient detection. In contrast, for noise trials (i.e. trial without temporal signals), there was a LVF-RH advantage. This LVF-RH advantage was observed when the entire stimulus duration was long (240 ms, Experiment 1), but was eliminated when the duration was short (120 ms, Experiment 2). In Experiment 3, where the gap was placed toward the end of the stimulus presentation, a LVF-RH advantage was found for noise trials whereas the RVF-LH advantage was eliminated for signal trials. It is likely that participants needed to monitor the stimulus for a longer period of time when the gap was absent (i.e. noise trials) or was placed toward the end of the presentation. The RH may therefore be more efficient in the sustained monitoring of visual temporal information whereas the LH is more efficient for transient detection.

Gap duration discrimination for frequency-asymmetric gap markers: Psychophysical and electrophysiological findings

This study investigated gap duration discrimination (GDD) for frequency-asymmetric gap markers, where one marker was a two-tone complex consisting of a primary tone and a secondary tone, and the other marker was the primary tone alone. Three experiments were undertaken to examine the order effect wherein performance is better when the two-tone marker is the leading marker than when it is the trailing marker. Experiment 1 demonstrated that GDD for frequency-asymmetric markers is intermediate between the boundaries of within-frequency-channel versus across-frequency-channel processing. Experiment 2 compared psychophysical performance with auditory brainstem responses (ABRs) elicited by the same stimuli. Whereas GDD thresholds were elevated for a complex trailing marker relative to a within-frequency-channel baseline, ABRs elicited by the complex marker were more robust. Experiment 3 tested the hypothesis that poor GDD performance with frequency-asymmetric markers is due to some form of nonenergetic, or informational, masking. The results did not support a role for informational masking conferred by synthetic listening; however, informational masking conferred by the occurrence of novel spectral events provided a parsimonious account. One possible interpretation is that the capacity to accurately encode a gap is undermined by the occurrence of novel spectral events that engage limited attentional resources.

Characterization of Muscular Rest Periods (gaps) in Long-term EMG of Older Men and Women

The ability to maintain functional independence in older adults is largely associated with the generation and control of purposeful movement. Laboratory studies indicate that with increasing age there is a decline in muscle strength and a decrease in force control. Limited studies are available on neuromuscular activity outside the laboratory in older adults, but initial data indicate that burst activity is greater in older adults compared with young adults and in women compared with men (Appl Physiol Nut Met 31 (S22), 2006). This difference in burst activity might be due to periods of silence in electromyography (EMG) activity. PURPOSE: To characterize periods of muscle silence (gaps) in young and old men and women for an 8-hour typical weekday. METHODS: EMG was recorded in the biceps brachii, triceps brachii, quadriceps femoris and hamstrings in 16 young (23 + 2.5 yrs; 8 men, 8 women) and 15 older (77 + 3.5 yrs; 8 men, 7 women) adults. A portable EMG device was utilized. Signals were pre-amplified (1000x), band pass filtered (20–450Hz), stored on a 512 MB flashcard and subsequently downloaded to Spike 2 for custom analysis. A gap was denned as an EMG interval <1% of the maximum isometric effort (MVE), and a duration of >0.1s. Total number of gaps, gap duration (sec), gap amplitude (% MVE), mean gap activity (% MVE) and gap rate (gaps/s) were assessed. RESULTS: The number of gaps recorded did not differ as a function of age (10%δ) or gender (14%δ). However, the mean duration (sec) of the gaps were ∼2 times longer in the young compared with old, and during periods of silence the amplitude and area of the gaps were also less (3-10%δ) in the young compared with the old. Gender differences were evident as mean duration of the gaps (sec) and area of the gaps (MVC*s) were longer (∼1.5 times) in men compared with women, yet gap amplitude (%MVC) was greater in women (∼0.8 times) compared with men. CONCLUSIONS: Shorter durations and higher amplitudes of gap activity during periods of EMG silence suggest that muscles of older adults are not as quiescent as muscles of young adults during periods of “rest”. As well, total gaps do not differ between genders but the duration and amplitudes which characterize a gap differ between men and women.

Pigeons’ memory for sequences of light flashes when gap duration is an unreliable discriminative cue

In Experiment 1, pigeons were trained with a 1-sec dark and a 1-sec houselight-illuminated delay interval to discriminate between sequences of two and four flashes of light (feeder illumination). The sequences could be discriminated on the basis of the number of flashes, the number of gaps, or the duration of the gap between flashes. A choose-few bias was obtained at extended dark delays, but not at extended illuminated delays. Pigeons appeared to confuse long dark delays with the longer gap between flashes on few-sample trials. In Experiment 2, additional sample sequences were included that made gap duration an unreliable cue for discriminating between the few and many samples. A significant choose-many bias was obtained at extended dark delay intervals, but no biased forgetting was found at extended illuminated delays. The pigeons appeared to discriminate light flash sequences by relying on multiple temporal features of a sequence rather than using an event switch to count flashes. The biased-forgetting effects observed appear to be due to instructional ambiguity that results from the similarity of the delay interval to features of the flash sequences.

Atypical pattern of discriminating sound features in adults with Asperger syndrome as reflected by the mismatch negativity

Asperger syndrome, which belongs to the autistic spectrum of disorders, is characterized by deficits of social interaction and abnormal perception, like hypo- or hypersensitivity in reacting to sounds and discriminating certain sound features. We determined auditory feature discrimination in adults with Asperger syndrome with the mismatch negativity (MMN), a neural response which is an index of cortical change detection. We recorded MMN for five different sound features (duration, frequency, intensity, location, and gap). Our results suggest hypersensitive auditory change detection in Asperger syndrome, as reflected in the enhanced MMN for deviant sounds with a gap or shorter duration, and speeded MMN elicitation for frequency changes.

A stratigraphic and tectonic review of the Italian Southern Alpine Permian

The South-Alpine Permian succession consists of continental and also, to the east of the Adige Valley, marine deposits. The former are made up of volcanic and siliciclastic rocks, while the latter, represented by the Bellerophon Formation of Late Permian age, include evaporites and shallow-marine sediments. However, in the Carnic Alps, marine deposition began earlier, from Carboniferous times. In this context, two major and well-differentiated tectono-stratigraphic units (TSUs) or cycles, separated by a marked regional unconformity and a gap of as-yet uncertain duration, are clearly evident. This paper aims at reviewing the current stratigraphic framework and correlating it to the most recent timescales. This research indicates that initial deposition of the Verrucano Lombardo/Val Gardena Sandstone red beds probably occurred in many places, such as in the Carnic Alps, during Middle Permian times. Consequently, this interpretation supports a reduction, at least locally, of the large time-gap suggested between the two above-mentioned cycles. Their respective evolution led to paleogeographic changes related to different structural and geodynamic settings. The Lower Permian stratigraphic sequence was mainly deposited in transtensional pull-apart and strike-slip intracontinental basins during the onset of regional uplift, with unroofing, collapse and stretching of the Variscan orogen, upwelling of the asthenosphere and intrusion of granitic melts into the crust. This episode could be interpreted as the final act of the “Hercynian (Variscan) Cycle”. It was followed by a tectonic event (the so-called “Mid-Permian Episode” in the literature) as a prelude to general plate reorganization and the opening of new oceans (such as Meliata-Maliak and Neotethys). In contrast, the Middle pro parte—Upper Permian stratigraphic sequence marks the development of more generalized extensional tectonics, compatible with a rifting regime. According to many authors, it is regarded as the beginning of the “Alpine Cycle”.

Gap duration discrimination for frequency-asymmetric gap markers: Psychophysical and electrophysiological findings

Gap duration discrimination for frequency-asymmetric gap markers: Psychophysical and electrophysiological findings

Memory for sequences of tone bursts in the rat: Reliance on temporal cues and evidence for an instructional ambiguity explanation of the choose-few effect

Two groups of rats were trained in a symbolic delayed matching-to-sample task with a 0-s delay to discriminate sample stimuli that consisted of sequences of tone bursts. For one group, sequences varied in number with total sequence duration controlled. For the other group, total sequence duration, sum of the tone durations, and sum of the gap durations were all controlled. The former group of rats acquired the discrimination, but the latter group of rats were not able to learn the discrimination with the additional temporal cues controlled. Retention functions for the group that acquired the discrimination exhibited a choose-many bias at the 1-s delay and a choose-few bias at the 8-s delay regardless of the similarity in the intertrial interval and delay interval illumination condition. The asymmetrical retention functions appeared to be due to instructional ambiguity which resulted from the similarity of the delay interval to temporal features of the tone burst sequence, such as the gap between tone bursts and the total duration of tone. In Experiment 2, diagnostic tests provided evidence that rats discriminated the sequences of tone bursts by timing and summing the duration of individual tone bursts rather than using an event switch to count tones. Like pigeons, rats use multiple temporal features rather than number to discriminate sequences of successive events.

Fine grain temporal analysis in aphasia: Evidence from auditory gap detection

Auditory temporal processing was investigated in individuals with acquired aphasia using a task in which they were asked to detect brief silent gaps inserted between noise segments modeled after formants in speech. To examine within-channel gap detection, gaps of 10, 20, 40, and 80ms duration were inserted between an initial segment (IS) and a trailing segment (TS) centered at the same frequency (1kHz). In a between-channel gap detection condition, gaps of 20, 40, 80, and 100ms duration were inserted between an IS that differed in frequency (4kHz) from the TS (1kHz). The effect of gap onset timing was examined in both conditions by systematically varying the duration of the IS by 10, 20, or 40ms. A combined analysis revealed that for both conditions and all gap and IS durations, individuals with aphasia produced fewer correct responses than age-matched neurologically intact controls. Separate condition analyses revealed that when noise segments were centered at the same frequency, individuals with aphasia demonstrated poorer accuracy in detecting 40 and 80ms gaps relative to normal controls (p<0.001). When gaps were inserted between noise segments differing in frequency, on average, aphasic subjects performed less accurately at durations of 40, 80 and 100ms (p<0.025). Detection in both groups decreased with smaller IS durations. The difficulties with gap detection observed in the aphasic group suggest the existence of fundamental problems in processing the temporal form or microstructure of sounds characterized by rapidly changing onset dynamics.

Static and dynamic spectro-temporal gap detection

Frequency-dependent measures of temporal processing are often based on temporal gap detection measured using sinusoids or bandpass noise. Some natural sounds, such as speech, are better characterized as relatively broadband sounds with low-amplitude portions restricted to narrow frequency regions. The present study reports the perception of analogous stimuli: static and dynamic spectro-temporal gaps embedded in broadband noise. In the first experiment, the temporal gap created a static spectral notch, the duration of which was the independent variable (gap duration in ms) and the width of which was fixed, in separate conditions being either 800 Hz or equal to one or three ERBs (equivalent rectangular bandwidth). The spectral notch was centered at either 800, 1600, 3200, or 6400 Hz. Gap onset relative to stimulus onset varied from 10 to 320 ms. In the second experiment, the temporal gap created a dynamic spectral notch, the lower and upper cutoff frequencies of which varied over the duration of the temporal gap much like a frequency sweep. Experimental parameters included the bandwidth of the notch in octaves and notch center frequency at gap onset and gap offset. The data will be considered in terms of temporal resolution, frequency resolution, and across-channel processing.

Adaptation to an Electropalatograph Palate: Acoustic, Impressionistic, and Perceptual Data

The purpose of this study was to evaluate adaptation to the electropalatograph (EPG) from the perspective of consonant acoustics, listener perceptions, and speaker ratings. Seven adults with typical speech wore an EPG and pseudo-EPG palate over 2 days and produced syllables, read a passage, counted, and rated their adaptation to the palate. Consonant acoustics, listener ratings, and speaker ratings were analyzed. The spectral mean for the burst (/t/) and frication (/s/) was reduced for the first 60-120 min of wearing the pseudo-EPG palate. Temporal features (stop gap, frication, and syllable duration) were unaffected by wearing the pseudo-EPG palate. The EPG palate had a similar effect on consonant acoustics as the pseudo-EPG palate. Expert listener ratings indicated minimal to no change in speech naturalness or distortion from the pseudo-EPG or EPG palate. The sounds [see text] were most likely to be affected. Speaker self-ratings related to oral comfort, speech, tongue movement, appearance, and oral sensation were negatively affected by the presence of the palatal devices. Speakers detected a substantial difference when wearing a palatal device, but the effects on speech were minimal based on listener ratings. Spectral features of consonants were initially affected, although adaptation occurred. Wearing an EPG or pseudo-EPG palate for approximately 2 hr results in relatively normal-sounding speech with acoustic features similar to a no-palate condition.

Effect of interphase gap and pulse duration on electrically evoked potentials is correlated with auditory nerve survival

We investigated the effect of pulse duration (PD) and interphase-gap (IPG) on the electrically-evoked auditory brain stem response (EABR) and viiith nerve compound action potential (ECAP) of deafened guinea pigs in order to test the hypothesis that the extent of change in these neural responses is affected by the histological status of the auditory nerve. Fifteen guinea pigs were deafened by co-administration of kanamycin and furosemide. Animals were acutely implanted with an 8-band electrode array at 1, 4 or 12 weeks following deafening. EABR and ECAP input/output functions were recorded in response to charge balanced biphasic current pulses. We determined the change in current required to equalize; (i) the EABR amplitude when the duration of the current pulse was doubled (104–208 μs/phase); and (ii) the EABR and ECAP amplitudes when the IPG was increased from 8 to 58 μs using a 104 μs/phase current pulse. Following the completion of each experiment the cochleae were examined quantitatively for spiral ganglion neuron survival. As expected, the current level required to evoke an EABR with equal amplitude was lower when the animal was stimulated with current pulses of 208 compared with 104 μs/phase. Moreover, the current level required to evoke EABR/ECAPs with equal amplitude was lower when current pulses had an IPG of 58 versus 8 μs. Importantly, there was a reduction in the magnitude of this effect with greater neural loss; the reduced efficacy of changing both PD and IPG on these electrically-evoked potentials was statistically correlated with neural survival. These results may provide a tool for investigating the contribution of auditory nerve survival to clinical performance among cochlear implant subjects.

Temporal processing deficits in the pre-senescent auditory system

This study tested the hypothesis that temporal processing deficits are evident in the pre-senescent (middle-aged) auditory system for listening tasks that involve brief stimuli, across-frequency-channel processing, and/or significant processing loads. A gap duration discrimination (GDD) task was employed that used either fixed-duration gap markers (experiment 1) or random-duration markers (experiment 2). Independent variables included standard gap duration (0, 35, and 250 ms), marker frequency (within- and across-frequency), and task complexity. A total of 18 young and 23 middle-aged listeners with normal hearing participated in the GDD experiments. Middle age was defined operationally as 40-55 years of age. The results indicated that middle-aged listeners performed more poorly than the young listeners in general, and that this deficit was sometimes, but not always, exacerbated by increases in task complexity. A third experiment employed a categorical perception task that measured the gap duration associated with a perceptual boundary. The results from 12 young and 12 middle-aged listeners with normal hearing indicated that the categorical boundary was associated with shorter gaps in the young listeners. The results of these experiments indicate that temporal processing deficits can be observed relatively early in the aging process, and are evident in middle age.

Time-sharing in pigeons: Independent effects of gap duration, position and discriminability from the timed signal

Previous data suggest that in a peak-interval procedure with gaps, memory for the pre-gap interval varies with the discriminability of the gap from the to-be-timed signal. Here we extend this finding by manipulating the pre-gap and gap intervals as well as the visual contrast between the gap and the to-be-timed signal. The delay in response function after the gap was found to vary with the duration and position of the gap. However, for each gap duration and position, the delay in response increased with the gap-signal contrast: at 60% gap-signal contrast pigeons continued to accumulate time during the gap, at 80% gap-signal contrast pigeons stopped timing during the gap, and at 100% gap-signal contrast pigeons reset their timing after the gap. Data are accounted for by a time-sharing model assuming two concurrent processes during the gap--time accumulation and memory decay controlled by the salience of the gap--whose interplay results in a continuum of responses in the gap procedure.

Effects of Noise-Induced Hearing Loss at Young Age on Voice Onset Time and Gap-in-Noise Representations in Adult Cat Primary Auditory Cortex

Here we show that mild hearing loss induced by noise exposure in early age causes a decrease in neural temporal resolution when measured in adulthood. We investigated the effect of this chronic hearing loss on the representation of a voice onset time (VOT) and a gap-duration continuum in primary auditory cortex (AI) in cats, which were exposed at the age of 6 weeks to a 120-dB SPL, 5-kHz 1/3 octave noise band for 2 h. The resulting hearing loss measured using auditory brainstem responses and cortical multiunit thresholds at 4-6 months of age was 20-40 dB between 1 and 32 kHz. Multiple single-unit activity was recorded in seven noise-exposed cats and nine control cats related to the presentation of a/ba/-/pa/ continuum in which VOT was varied in 5-ms step from 0 to 70 ms. We also obtained data for noise bursts with gaps, of duration equal to the VOT, embedded in noise 5 ms after the onset. Both stimuli were presented at 65 dB SPL. Minimum VOT and early-gap duration were defined as the lowest value in which an on-response, significantly above the spontaneous activity, to both the leading and trailing noise bursts or vowel was obtained. The mild chronic noise-induced hearing loss increased the minimum detectable VOT and gap duration by 10 ms. We also analyzed the maximum firing rate (FRmax) and the latency of the responses as a function of VOT and gap duration and found a significant reduction in the FRmax to the trailing noise burst for gap durations above 50 ms. This suggests that mild hearing loss acquired in early age may affect cortical temporal processing in adulthood.