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N Niccum

Publications and source records attributed to N Niccum.

At least 19 recordsLinked to original sources
PubMed1994

A Revised Speech Intelligibility Rating (RSIR) test: listeners with normal hearing.

Two experiments were conducted to examine the intelligibility of 72 passages of connected discourse prepared by Cox and McDaniel in their development of the Speech Intelligibility Rating (SIR) test. Intelligibility was assessed with a method-of-adjustment (MOA) procedure in which listeners adjusted the level of a multi-talker babble until they could just understand 50% of a passage; the measure of intelligibility was the signal-to-babble ratio, dB S/B. The objective was to develop a Revised Speech Intelligibility Rating (RSIR) test that would comprise a large number of equivalent passages that produce reliable intelligibility measures. In experiment 1, the S/B ratio was based on the overall root-mean-square (rms) levels of speech and babble, as represented by the average level of frequent peaks observed on a VU meter. Across all 72 passages, mean intelligibility was -1.43 dB S/B, and the measure of intelligibility for 42 passages was within +/- 0.5 dB of the overall mean for all 72 passages. In experiment 2, the S/B ratio was based on long-term rms levels of speech and babble measured in 16 one-third-octave bands, with center frequencies from 160 to 5000 Hz. In an effort to achieve greater equivalence in intelligibility among passages, the overall rms level of each passage was attenuated by the difference between SB16-band for an individual passage and S/B16-band for a reference passage. Mean intelligibility across all 72 passages was -8.06 dB, and the measure of intelligibility was within +/- 0.5 dB of the overall mean for 64 of the 72 passages. For those 64 passages, the 95% critical difference for five MOAs was 0.72 dB, which corresponds to an estimated percentage critical difference of 10.8%.

Acoustic Stimulation↗
PubMed1992

Relative ear advantage and element duration.

Lauter [J. Acoust. Soc. Am. 71, 701-707 (1982)] reported that although the magnitude and direction of the absolute ear advantage for speech and nonspeech sound sets presented dichotically varies considerably among listeners, consistent patterns of a relative ear advantage (EArel) across sound sets are preserved from listener to listener. She further claimed that EArel appeared to be related to the duration of elements that composed a sequence. The existence of EArel is investigated for four sound sets: CV nonsense syllables and pitch patterns that were composed of 50-, 80-, or 120-ms tones. The paradigm was target monitoring, a Yes/No task in which listeners attended to only one ear and listened for the presence of a target signal. The results failed to confirm that listeners have a consistent relative ear advantage related to element duration for nonspeech sound sets.

Acoustics↗
PubMed1991

Interpretation of outcome on dichotic listening tests following stroke.

The historical basis for interpretation of the dichotic listening performance of aphasic patients is presented. Most studies agree with respect to outcome; aphasic patients as a group tend to have ear advantages (EAs) that are shifted to the left relative to non-brain-damaged listeners. Studies disagree as to whether this difference reflects a shift toward right hemisphere dominance for language processing or a "contralateral ear lesion effect." Emphasis is placed on the most recent additions to the literature, including discussion of factors that affect the accuracy with which lesions can be localized. The conclusion reached is that variables other than dominance determine the direction of ear advantage for many aphasic listeners.

Auditory Pathways↗
PubMed1989

Effects of decision variables on stimulus dominance in dichotic listening.

Stimulus dominance occurs when one member of a dichotic pair is identified more accurately than the other member. The contribution that attentional factors, listener biases, and other nonsensory variables make to stimulus dominance was assessed by comparison of scores obtained in a conventional two-ear monitoring task with scores obtained in a yes/no target-monitoring task. The target-monitoring paradigm is an application of signal detection theory to dichotic listening that allows calculation of d', a measure of perceptual sensitivity. Patterns of dominance for the two paradigms were very similar, which indicates that nonsensory factors had little influence in determining those patterns.

Adult↗
PubMed1989

Comparison of target monitoring and two-ear monitoring dichotic listening procedures.

The dichotic listening performance of 40 listeners was assessed for consonant-vowel (CV) nonsense syllables with two procedures. One was a conventional two-ear monitoring task in which listeners attended to both ears and provided two responses for each pair of syllables. The ear advantage was described by % RE-% LE. The second was target monitoring, a yes/no task in which listeners attended to only one ear and listened for the presence of a target syllable. That procedure provided both hit and false alarm rates for each ear, and the ear advantage was described by P(C)maxRE-P(C)maxLE, which is insensitive to decision variables. Although both procedures yielded mean right-ear advantages (REA), the mean REA of +7.5% with two-ear monitoring was significantly different from the mean REA of +2.6% with target monitoring. In addition, although 62% of the listeners had a significant REA with the conventional procedure, only 40% had a significant REA with target monitoring. Decision variables, which are not controlled with conventional dichotic testing methods, may contribute to the ear advantage as it is described frequently in the literature.

Adult↗
PubMed1987

Effects of simulated conductive hearing loss on dichotic listening performance for digits.

This experiment assessed conditions under which simulated conductive hearing loss would affect performance on a digit dichotic test. Losses were simulated by insertion of EAR plugs, and each subject served as his/her own control. Performance for left ear plugged and right ear plugged conditions was compared with performance in a normal hearing condition (neither ear plugged). Conductive losses did not affect dichotic performance at test intensities 12 dB above the "knees" of monotic performance-intensity functions for the plugged ears (95% correct points) but did affect dichotic performance for some listeners at intensities that were within 8 dB of the monotic knees.

Acoustic Stimulation↗
PubMed1986

Longitudinal dichotic listening patterns for aphasic patients. I. Description of recovery curves.

Aphasic patients were given digit and noun dichotic listening tests at monthly intervals during the first 6 months postonset of left hemisphere ischemic infarctions. Significant changes in performance were observed that consisted of parallel increases in scores for the two ears, and thus did not support the hypothesis that language recovery is mediated by transfer of language dominance from the left to the right hemisphere. Reliable differences also were noted between performance on the two tests. RE scores accounted for most of the variance among patients in performance on dichotic tests and, as such, appeared to be the best measure for characterizing individual differences.

Adaptation, Physiological↗
PubMed1986

Longitudinal dichotic listening patterns for aphasic patients. II. Relationship with lesion variables.

Dichotic listening scores and information on lesion size and location were obtained for aphasic patients. All patients had a reduction in dichotic scores at 1 month postonset of symptoms, but some patients returned to normal levels of performance by 6 months postonset. Lesion location was the main determinant of patterns of performance. Right ear scores from the dichotic digit test closely reflected the presence or absence of lesions involving Heschl's gyrus. What appeared to be an effect of lesion volume was confounded by the relationship between increasing lesion volume and a greater likelihood of damage to Heschl's gyrus.

Adult↗
PubMed1986

Longitudinal dichotic listening patterns for aphasic patients. III. Relationship to language and memory variables.

Longitudinal dichotic scores were obtained for aphasic patients for whom extensive language and memory data were also available. Severity of language impairments was related to ear advantage, but this occurred because larger lesions yielded more severe language impairments and were more likely to involve Heschl's gyrus. Extent of language recovery was not related to changes in ear dominance. Relationships that occurred generally supported a functional-anatomical interpretation which stressed the importance of the integrity of the posterior superior temporal lobe to performance both on dichotic tests and on specific language or memory tests.

Adult↗
PubMed1985

The critical role of Wernicke's area in sentence repetition.

The anatomical correlates of persistent deficits in sentence repetition were studied in a group of 32 right-handed patients with fluent aphasia caused by left hemisphere ischemic stroke. Patients whose ability to repeat remained impaired by 6 months after onset almost without exception had damage to Wernicke's area. Furthermore, all patients with damage to Wernicke's area had impaired repetition 6 months after onset. The most consistent lesion correlating with chronic impairment of repetition, therefore, was one destroying parts or all of Wernicke's area. Lesions outside of this area typically resulted in milder impairment of repetition that resolved within a few months. Only 5 patients had no repetition impairment when tested early (1 month after onset). These patients all had lesions anterior to the rolandic fissure, some including Broca's area.

Adult↗
PubMed1985

Effects of stimulus material on the dichotic listening performance of patients with sensorineural hearing loss.

Dichotic listening scores were obtained from 27 patients with sensorineural hearing loss in response to four dichotic speech tests: digits, vowel words, consonant words, and CV nonsense syllables. Monotic performance-intensity functions for each ear were defined with the CV syllables, and the four dichotic tests were administered at an intensity that produced asymptotic monotic performance for both ears with the CV syllables. Four blocks of 30 pairs of items per block were presented for each dichotic test, which produced 240 responses per test for each patient. Reliable differences among left-ear scores, right-ear scores, performance level, and the ear advantage were observed among the four tests. The digit test appeared to be most promising for assessing central auditory function when the patient had a sensorineural hearing loss because performance for the digits was only slightly affected by the peripheral loss.

Adult↗
PubMed1984

Recovery of single word comprehension: CT-scan correlates.

9tory comprehension for single words, as measured by the BDAE Word Discrimination subtest, was studied longitudinally in a group of 37 aphasic patients. The majority of the patients had impaired performance at 1 month postonset, but recovery by Month 6 postonset was quite striking. Damage to Wernicke's area did not preclude recovery of single word comprehension to within the normal range. Only patients with very extensive left hemisphere lesions had incomplete recovery of single word comprehension.

Adult↗
PubMed1984

Recovery of naming in aphasia: relationship to fluency, comprehension and CT findings.

We assessed oral naming skill after left hemisphere ischemic stroke in 54 right-handed aphasics. Initially, almost all had moderate to severe disability in oral naming. After 6 months, normal scores were achieved by one-third of the patients, all with lesions less than 60 cm3 in volume. Only 2 of 18 patients who were nonfluent at 6 months had normal naming then. Among patients with lesions less than 60 cm3 and persistently poor naming, there were two discrete lesion sites: posterior superior temporal-inferior parietal (semantic paraphasic errors) and insula-putamen (phonologic paraphasic errors). Individual variability was notable, with several patients regaining normal naming ability despite posterior temporal or insula-putamen lesions.

Adult↗
PubMed1983

Computed tomographic scan correlates of auditory comprehension deficits in aphasia: a prospective recovery study.

Lesion localization and volume as assessed on computed tomography were analyzed to determine their relationships to auditory comprehension deficits following left hemisphere ischemic stroke in 39 patients. Auditory comprehension was initially tested approximately four weeks after onset, and then monthly for five months, using the Token Test, a series of commands of increasing complexity. Computed tomographic scans obtained five months after onset were used for lesion localization and volume determination. Lesions in the posterior superior temporal and infrasylvian supramarginal regions were strongly associated with poor outcome. Patients with initially preserved auditory comprehension tended to have lesions that spared these regions, whereas patients with persistent deficits had lesions that included these regions. Six of 8 patients who initially had severe deficits in auditory comprehension but recovered completely lacked lesions in these regions. Lesion volume except when very large or very small was not closely associated with outcome.

Adult↗
PubMed1983

Reversal of ear advantage in recovery from aphasia: a case report.

A reversal from a left ear advantage to a right ear advantage on a digit dichotic listening test was observed during the first 3 months post-onset of aphasia in a 52-yr-old male patient. Explanations for this pattern of recovery were discussed under both a "lesion effect" and a "dominance effect" interpretation.

Aphasia↗
PubMed1983

Dichotic listening performance, language impairment, and lesion location in aphasic listeners.

This investigation sought to identify relations between dichotic listening performance and both specific language functions and CT scan evidence of lesion location in order to determine whether the nature of these relations would support either "dominance effect" or "lesion effect" interpretations of the dichotic scores. Twenty-five aphasic patients completed our digit dichotic listening test, the Boston Diagnostic Aphasia Examination (BDAE), an experimental sentence comprehension test, and a digit immediate memory span test. Right ear scores (and the ear advantage) accurately reflected the integrity of the central auditory structures for all but one of the patients, and thus were interpreted as "lesion effects." These same right ear scores also were related more strongly to performance on phrase repetition subtests of the BDAE and to scores obtained on our sentence comprehension test than to the other language measures analyzed. These relations were maintained even when general measures of auditory comprehension and immediate memory were held constant through the use of partial correlations. Both "dominance" and "lesion" effect interpretations were discussed, but the "lesion effect" interpretation more adequately characterized the data. That is, the integrity of the posterior, superior temporal area seemed to be essential for perception of right ear stimuli on the digit dichotic test and for accurate performance on specific language tests.

Adult↗