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PubMed1978

On the role of spatial and temporal cues in the perception of the pitch of complex tones.

This paper describes a new approach to pitch perception. It focuses attention on the slight difference between the pitch of complex tone and the pitch of a pure tone with the same (fundamental) frequency. This approach is based on the assumption that pitch perception is based on both spatial and temporal cue analysis. In this study, the values provided by the temporal cue are calculated from physiological data from the auditory nerve fibers. The possible ratios of the pitch of complex tones relative to the pitch of pure tones at various frequencies are predicted. Psychophysical experimental results strongly support this prediction. In addition, another experiment suggests that the above psychophysical effect is not based upon a mutual masking effect in the spatial domain.

Cues↗
PubMed1988

Burying straw men in imaginary graves: a reply to Kewley-Port, Watson, and Foyle (1988).

Kewley-Port, Watson, and Foyle [J. Acoust. Soc. Am. 83, 1133-1145 (1988)] describe a study that uses several different procedures to measure thresholds for stimuli whose components differ in temporal onset. Unfortunately, misunderstandings and misconceptions (shared with other recent publications) resulted in conclusions that are both unnecessary and unwarranted. The Kewley-Port et al. article is discussed in terms of often replicated published findings on temporal order thresholds, and current misconceptions of perceptual concepts and models.

Attention↗
PubMed1990

Spectral and duration properties of front vowels as cues to final stop-consonant voicing.

The perception of voicing in final velar stop consonants was investigated by systematically varying vowel duration, change in offset frequency of the final first formant (F1) transition, and rate of frequency change in the final F1 transition for several vowel contexts. Consonant-vowel-consonant (CVC) continua were synthesized for each of three vowels, [i,I,ae], which represent a range of relatively low to relatively high-F1 steady-state values. Subjects responded to the stimuli under both an open- and closed-response condition. Results of the study show that both vowel duration and F1 offset properties influence perception of final consonant voicing, with the salience of the F1 offset property higher for vowels with high-F1 steady-state frequencies than low-F1 steady-state frequencies, and the opposite occurring for the vowel duration property. When F1 onset and offset frequencies were controlled, rate of the F1 transition change had inconsistent and minimal effects on perception of final consonant voicing. Thus the findings suggest that it is the termination value of the F1 offset transition rather than rate and/or duration of frequency change, which cues voicing in final velar stop consonants during the transition period preceding closure.

Adult↗
PubMed1992

Segmental durations in the vicinity of prosodic phrase boundaries.

Numerous studies have indicated that prosodic phrase boundaries may be marked by a variety of acoustic phenomena including segmental lengthening. It has not been established, however, whether this lengthening is restricted to the immediate vicinity of the boundary, or if it extends over some larger region. In this study, segmental lengthening in the vicinity of prosodic boundaries is examined and found to be restricted to the rhyme of the syllable preceding the boundary. By using a normalized measure of segmental lengthening, and by compensating for differences in speaking rate, it is also shown that at least four distinct types of boundaries can be distinguished on the basis of this lengthening.

Attention↗
PubMed1996

The perception of temporal patterns for electrical stimulation presented at one or two intracochlear sites.

The question of how well the temporal structure in pulsatile electrical stimulation is perceived, and the nature of the information that may be conveyed by this temporal structure, is of importance to the further development of speech processing strategies for cochlear implants. The two experiments described here investigated the perception of temporal fine structure in amplitude modulated 1-kHz pulse trains, both when a single electrode position was used, and when the pulses alternated between two electrode positions. Five subjects with the Mini System 22 implant took part in these experiments. The amplitude modulations were constructed so that all dual-electrode stimuli had the same temporal pattern on each individual electrode but differed in the aggregate temporal pattern A hypothesis was investigated that subjects perceive the aggregate temporal pattern rather than the pattern at each individual electrode place, only when the electrodes are less than a critical distance apart. The first of these two experiments used a four-interval forced-choice task to measure the ability of subjects to detect changes in the aggregate temporal pattern. At electrode distances greater than 3 to 4 mm, subjects could no longer perceive the aggregate pattern, confirming the hypothesis. The second experiment used a single-interval pitch estimation task to test the hypothesis that the perceptual differences in temporal patterns measured in the previous experiment were classified similarly to rate pitch differences by the subjects. The results confirmed this hypothesis, and showed that the pitch of the modulated stimuli could be predicted by the expected inter-pulse intervals in the excited neural population.

Adult↗
PubMed1998

Speech recognition with altered spectral distribution of envelope cues.

Recognition of consonants, vowels, and sentences was measured in conditions of reduced spectral resolution and distorted spectral distribution of temporal envelope cues. Speech materials were processed through four bandpass filters (analysis bands), half-wave rectified, and low-pass filtered to extract the temporal envelope from each band. The envelope from each speech band modulated a band-limited noise (carrier bands). Analysis and carrier bands were manipulated independently to alter the spectral distribution of envelope cues. Experiment I demonstrated that the location of the cutoff frequencies defining the bands was not a critical parameter for speech recognition, as long as the analysis and carrier bands were matched in frequency extent. Experiment II demonstrated a dramatic decrease in performance when the analysis and carrier bands did not match in frequency extent, which resulted in a warping of the spectral distribution of envelope cues. Experiment III demonstrated a large decrease in performance when the carrier bands were shifted in frequency, mimicking the basal position of electrodes in a cochlear implant. And experiment IV showed a relatively minor effect of the overlap in the noise carrier bands, simulating the overlap in neural populations responding to adjacent electrodes in a cochlear implant. Overall, these results show that, for four bands, the frequency alignment of the analysis bands and carrier bands is critical for good performance, while the exact frequency divisions and overlap in carrier bands are not as critical.

Adult↗
PubMed1998

Temporal and spatio-temporal vibrotactile displays for voice fundamental frequency: an initial evaluation of a new vibrotactile speech perception aid with normal-hearing and hearing-impaired individuals.

Four experiments were performed to evaluate a new wearable vibrotactile speech perception aid that extracts fundamental frequency (F0) and displays the extracted F0 as a single-channel temporal or an eight-channel spatio-temporal stimulus. Specifically, we investigated the perception of intonation (i.e., question versus statement) and emphatic stress (i.e., stress on the first, second, or third word) under Visual-Alone (VA), Visual-Tactile (VT), and Tactile-Alone (TA) conditions and compared performance using the temporal and spatio-temporal vibrotactile display. Subjects were adults with normal hearing in experiments I-III and adults with severe to profound hearing impairments in experiment IV. Both versions of the vibrotactile speech perception aid successfully conveyed intonation. Vibrotactile stress information was successfully conveyed, but vibrotactile stress information did not enhance performance in VT conditions beyond performance in VA conditions. In experiment III, which involved only intonation identification, a reliable advantage for the spatio-temporal display was obtained. Differences between subject groups were obtained for intonation identification, with more accurate VT performance by those with normal hearing. Possible effects of long-term hearing status are discussed.

Adult↗
PubMed1999

Investigation of the effects of temporal and spatial interactions on speech-recognition skills in cochlear-implant subjects.

Forward masking was investigated as a measure of spectral and temporal interactions. Such interactions may adversely affect speech recognition in cochlear-implant subjects. Seven subjects, implanted with the Nucleus 22 device, performed a forward-masking task. They also performed an electrode-discrimination task in order to measure spectral interactions without temporal interactions. Correlation analysis indicated a significant relationship between data obtained in the two tasks (p < 0.1). The two tasks were also correlated with the subjects' scores from five measures of speech recognition. Forward masking and electrode discrimination were strongly correlated with measures requiring consonant and phoneme recognition, respectively. These results indicate that the relationship between forward masking and speech recognition may be due, in part, to a lack of spectral resolution. The data also indicate that consonants may be more readily masked than vowels. Forward-masking data measured for all clinically programmed electrodes in three of the seven subjects were used with a model of the spectral maxima sound processor (SMSP) to estimate the number of electrodes stimulated during a consonant that might be masked by prior presentation of a vowel. These results suggest that temporal interactions across electrodes may be a factor in speech-recognition abilities of some cochlear-implant subjects.

Adult↗
PubMed2005

Spatial coupling in children with hemiplegic cerebral palsy during bimanual circle and line drawing.

The effect of amplitude incongruence (small circles-large circles) and form incongruence (circles-lines) on the performance of the affected and non-affected arm was examined in 12 children with hemiplegic cerebral palsy in bimanual rhythmic drawing tasks. Amplitude and form incongruence are assumed to be associated with aspects of movement execution and movement planning, respectively. The following questions were addressed: Does amplitude or form incongruence in bimanual coordination result in: (a) accommodation of the affected or non-affected arm, or both, (b) an increase of temporal variability of drawing movements of the affected or non-affected arm, and (c) a decrease of bimanual coordination stability? Form incongruence resulted in accommodation of both affected and non-affected arm in a similar way found in non-disabled participants. Despite this accommodation, the temporal variability of both affected and non-affected arm was increased, and coordination stability decreased, because the spatial trajectories of affected and non-affected arm were still rather dissimilar. Amplitude incongruence resulted in accommodation of either the affected arm (large circles required) or non-affected arm (small circles required), and in an increase or decrease of temporal variability of the affected arm, depending on the degree of spatial similarity of the trajectories of affected and non-affected arm. These findings suggest that in children with hemiplegic cerebral palsy aspects of movement execution, but not aspects of movement planning are affected by the "hemiplegic"

Cerebral Palsy↗
PubMed1999

A multi-differential neuromorphic approach to motion detection.

This paper presents a multi-differential neuromorphic approach to motion detection. The model is based evidence for a differential operators interpretation of the properties of the cortical motion pathway. We discuss how this strategy, which provides a robust measure of speed for a range of types of image motion using a single computational mechanism, forms a useful framework in which to develop future neuromorphic motion systems. We also discuss both our approaches to developing computational motion models, and constraints in the design strategy for transferring motion models to other domains of early visual processing.

Animals↗
PubMed1990

Comparison of measured and perceived time values for radiologists' work: impact on relative value scales.

The authors compared the actual time required by radiologists to perform and/or interpret common diagnostic radiologic examinations with the times the same radiologists perceived were necessary (as determined with a survey) to perform and/or interpret those same examinations. Average measured times ranged from 1.7 minutes for radiologic examinations of extremities to 113.2 minutes for interventional procedures. Average survey times ranged from 3.2 minutes for examinations of extremities to 84.4 minutes for cerebral angiography. The mean difference between measured and survey times for all examinations was 48.6%. Relative value scales were developed based on measured and survey times, with the upper gastrointestinal examination assigned the base unit of 100. The difference between the measured-time and survey-time relative value scales was 98% on average for the 16 examinations compared. The study suggests that there is a need for actual measurement of at least the time component of physician work if resource-based relative value scales are to be used as the basis for physician compensation.

Academic Medical Centers↗
PubMed2003

Independent processing of the temporal and ordinal structure of movement sequences.

We investigated if the temporal and ordinal structures of sequences can be represented and learned independently. In Experiment 1, subjects learned three rhythmic sequences of key presses with the right index finger: Combined consisted of nine key presses with a corresponding temporal structure of eight intervals; Temporal had the temporal structure of Combined but was performed on one key; Ordinal had the ordinal structure of Combined but an isochronous rhythm. Subjects were divided into two groups. Group 1 first learned Combined, then Temporal and Ordinal; Group 2 first learned Temporal and Ordinal, then Combined. Strong transfer effects were seen in both groups. In Group 1, having learned combined facilitated the learning of the temporal (Temporal) or ordinal (Ordinal) sequence alone; in Group 2, having learned Temporal and Ordinal facilitated the learning of Combined, where the two are combined. This supports that subjects had formed independent temporal and ordinal representations. In Experiment 2, we investigated if these can be learned independently. Subjects repeatedly reproduced sequences with fixed temporal and random ordinal structure; random temporal and fixed ordinal structure; and random temporal and ordinal structures. Temporal and ordinal learning was seen only in the first and second sequences, respectively. In summary, we provide evidence for the existence of independent systems for learning and representation of ordinal and temporal sequences and for implicit learning of temporal sequences. This may be important for fast learning and flexibility in motor control.

Adult↗
PubMed1993

Encoding of head acceleration in vestibular neurons. I. Spatiotemporal response properties to linear acceleration.

1. Extracellular recordings were made in and around the medial vestibular nuclei in decerebrated rats. Neurons were functionally identified according to their semicircular canal input on the basis of their responses to angular head rotations around the yaw, pitch, and roll head axes. Those cells responding to angular acceleration were classified as either horizontal semicircular canal-related (HC) or vertical semicircular canal-related (VC) neurons. The HC neurons were further characterized as either type I or type II, depending on the direction of rotation producing excitation. Cells that lacked a response to angular head acceleration, but exhibited sensitivity to a change in head position, were classified as purely otolith organ-related (OTO) neurons. All vestibular neurons were then tested for their response to sinusoidal linear translation in the horizontal head plane. 2. Convergence of macular and canal inputs onto central vestibular nuclei neurons occurred in 73% of the type I HC, 79% of the type II HC, and 86% of the VC neurons. Out of the 223 neurons identified as receiving macular input, 94 neurons were further studied, and their spatiotemporal response properties to sinusoidal stimulation with pure linear acceleration were quantified. Data were obtained from 33 type I HC, 22 type II HC, 22 VC, and 17 OTO neurons. 3. For each neuron the angle of the translational stimulus vector was varied by 15, 30, or 45 degrees increments in the horizontal head plane. In all tested neurons, a direction of maximum sensitivity was identified. An interesting difference among neurons was their response to translation along the direction perpendicular to that that produced the maximum response ("null" direction). For the majority of neurons tested, it was possible to evoke a nonzero response during stimulation along the null direction always had response phases that varied as a function of stimulus direction. 4. These spatiotemporal response properties were quantified in two independent ways. First, the data were evaluated on the basis of the traditional one-dimensional principle governed by the "cosine gain rule" and constant response phase at different stimulus orientations. Second, the response gain and phase values that were empirically determined for each orientation of the applied linear stimulus vector were fitted on the basis of a newly developed formalism that treats neuronal responses as exhibiting two-dimensional spatial sensitivity. Thus two response vectors were determined for each neuron on the basis of its response gain and phase at different stimulus directions in the horizontal head plane.(ABSTRACT TRUNCATED AT 400 WORDS)

Acceleration↗