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PubMed2002

Quantifying the intelligibility of speech in noise for non-native listeners.

When listening to languages learned at a later age, speech intelligibility is generally lower than when listening to one's native language. The main purpose of this study is to quantify speech intelligibility in noise for specific populations of non-native listeners, only broadly addressing the underlying perceptual and linguistic processing. An easy method is sought to extend these quantitative findings to other listener populations. Dutch subjects listening to Germans and English speech, ranging from reasonable to excellent proficiency in these languages, were found to require a 1-7 dB better speech-to-noise ratio to obtain 50% sentence intelligibility than native listeners. Also, the psychometric function for sentence recognition in noise was found to be shallower for non-native than for native listeners (worst-case slope around the 50% point of 7.5%/dB, compared to 12.6%/dB for native listeners). Differences between native and non-native speech intelligibility are largely predicted by linguistic entropy estimates as derived from a letter guessing task. Less effective use of context effects (especially semantic redundancy) explains the reduced speech intelligibility for non-native listeners. While measuring speech intelligibility for many different populations of listeners (languages, linguistic experience) may be prohibitively time consuming, obtaining predictions of non-native intelligibility from linguistic entropy may help to extend the results of this study to other listener populations.

Adolescent↗
PubMed2002

Quantifying the intelligibility of speech in noise for non-native talkers.

The intelligibility of speech pronounced by non-native talkers is generally lower than speech pronounced by native talkers, especially under adverse conditions, such as high levels of background noise. The effect of foreign accent on speech intelligibility was investigated quantitatively through a series of experiments involving voices of 15 talkers, differing in language background, age of second-language (L2) acquisition and experience with the target language (Dutch). Overall speech intelligibility of L2 talkers in noise is predicted with a reasonable accuracy from accent ratings by native listeners, as well as from the self-ratings for proficiency of L2 talkers. For non-native speech, unlike native speech, the intelligibility of short messages (sentences) cannot be fully predicted by phoneme-based intelligibility tests. Although incorrect recognition of specific phonemes certainly occurs as a result of foreign accent, the effect of reduced phoneme recognition on the intelligibility of sentences may range from severe to virtually absent, depending on (for instance) the speech-to-noise ratio. Objective acoustic-phonetic analyses of accented speech were also carried out, but satisfactory overall predictions of speech intelligibility could not be obtained with relatively simple acoustic-phonetic measures.

Adult↗
PubMed1994

Intelligibility of conversational and clear speech in noise and reverberation for listeners with normal and impaired hearing.

The effect of articulating clearly on speech intelligibility is analyzed for ten normal-hearing and two hearing-impaired listeners in noisy, reverberant, and combined environments. Clear speech is more intelligible than conversational speech for each listener in every environment. The difference in intelligibility due to speaking style increases as noise and/or reverberation increase. The average difference in intelligibility is 20 percentage points for the normal-hearing listeners and 26 percentage points for the hearing-impaired listeners. Two predictors of intelligibility are used to quantify the environmental degradations: The articulation index (AI) and the speech transmission index (STI). Both are shown to predict, reliably, performance levels within a speaking style for normal-hearing listeners. The AI is unable to represent the reduction in intelligibility scores due to reverberation for the hearing-impaired listeners. Neither predictor can account for the difference in intelligibility due to speaking style.

Adult↗
PubMed1998

Normal intelligence with severe insulin-like growth factor I deficiency due to growth hormone receptor deficiency: a controlled study in a genetically homogeneous population.

Superior school performance was reported for 52 Ecuadorian probands with severe deficiency of insulin-like growth factor I (IGF-I) due to GH receptor deficiency (GHRD) resulting from homozygosity for the E180 splice mutation of the GHR. In contrast, subnormal intelligence was reported in a study of 18 genetically heterogeneous Israeli patients, attributed to frequent hypoglycemia or IGF-I dependence of brain development. This study is the first controlled evaluation of the intellectual ability of patients with GHRD. We compared the intelligence of 18 patients of school age (mean +/- SD age, 11.5 +/- 2.8 yr), 42 of their relatives (11.5 +/- 2.8 yr), and 28 community controls (10.0 +/- 0.8 yr), using a battery of intelligence tests that have been validated in cross-cultural research, designed to minimize the effects of physical size, motor coordination, and cultural background. Because all patients had the same GHR mutation, for which the carrier state could be determined, this study also investigated whether heterozygosity for mutation of the GHR among unaffected relatives is associated with intelligence. The intellectual ability of the patients with GHRD was not significantly different from that of their relatives (P > 0.05) on the psychometric tests of intelligence and was comparable to that of the community controls on the chronometric tests. Homozygosity or heterozygosity for the mutation in the GHR gene common to Ecuadorian patients was unrelated to intelligence (P > 0.05). These results indicate that the gene defect causing GHRD is not related to intelligence in the Ecuadorian population. They also indicate that GH-induced IGF-I production is not required for normal brain growth in utero or for postnatal intellectual development.

Adolescent↗
PubMed1997

Lead exposure and intelligence in 7-year-old children: the Yugoslavia Prospective Study.

For a prospective study of lead exposure and early development, we recruited pregnant women from a lead smelter town and from an unexposed town in Yugoslavia and followed their children through 7 years of age. In this paper we consider associations between lifetime lead exposure, estimated by the area under the blood lead (BPb) versus time curve (AUC7), and intelligence, with particular concern for identifying lead's behavioral signature. The Wechsler Intelligence Scales for Children-Version III (WISC-III) was administered to 309 7-year-old children, 261 of whom had complete data on intelligence, blood lead, and relevant sociodemographic covariates (i.e., Home Observation for the Measurement of the Environment (HOME), birth weight, gender, sibship size, and maternal age, ethnicity, intelligence, and education). These showed anticipated associations with 7-year intelligence, explaining 41-4% of the variance in Full Scale, Performance, and Verbal IQ. Before covariate adjustment, AUC7 was unrelated to intelligence; after adjustment, AUC7 explained a significant 2.8%-4.2% of the variance in IQ. After adjustment, a change in lifetime BPb from 10 to 30 micro/dl related to an estimated decrease of 4.3 Full Scale IQ points; estimated decreases for Verbal and Performance IQ were 3.4 and 4.5 points, respectively. AUC7 was significantly and negatively related to three WISC-III factor scores: Freedom from Distractibility, Perceptual Organization, and Verbal Comprehension; the association with Perceptual Organization was the strongest. Consistent with previous studies, the IQ/lead association is small relative to more powerful social factors. Findings offer support for lead's behavioral signature; perceptual-motor skills are significantly more sensitive to lead exposure than are the language-related aspects of intelligence.

Child↗
PubMed2002

Assessing intelligibility in speakers with cleft palate: a critical review of the literature.

OBJECTIVE: A literature review was conducted in order to investigate three research questions: how is speech intelligibility being measured in speakers with cleft lip and palate? Is intelligibility adequately being distinguished from related measures such as acceptability? Has there been an increased understanding of intelligibility deficits in speakers with cleft lip and palate? Fifty-seven relevant articles published between 1960 and 1998 were included in the analysis. RESULTS: The results showed an increase in the number of articles that included a measure of intelligibility or a similar measure. Several concerns were raised as a result of the review, including the reliability and validity of measures being employed, adequate definition and differentiation of terms, and the need to determine speech and nonspeech variables contributing to reductions in intelligibility. Relevant literature on intelligibility from fields outside cleft lip and palate is reviewed, and a number of recommendations are made regarding the measurement of intelligibility in speakers with cleft lip and palate.

Articulation Disorders↗
PubMed2001

Relative roles of cognitive ability and practical intelligence in the prediction of success.

Initial investigations into the construct of practical intelligence have identified a new general factor of practical intelligence (gp), which is believed to be independent of general cognitive ability. This construct, gp, is also believed to be a better predictor of success than cognitive ability, personality, or any combination of variables independent of gp. The existence of this construct and its independence from Spearman's g is, however, under debate. The purpose of the present study is to investigate both the relationship between gp and g and the relative roles of practical intelligence and cognitive ability in the prediction of success. The participants included 197 college students. Each completed both the Multidimensional Aptitude Battery and Sternberg and Wagner's measure of practical intelligence in academic psychology. The results of structural equation modeling support Sternberg and Wagner's assertion that practical intelligence and general cognitive ability are relatively independent constructs. Results of regression analysis, however, do not support their contention that practical intelligence is related to success after controlling for general cognitive ability. Implications of these results for research and theory on practical intelligence are discussed.

Adult↗
PubMed2001

Speech intelligibility after glossectomy and speech rehabilitation.

BACKGROUND: Oral tumor resections cause articulation deficiencies, depending on the site, extent of resection, type of reconstruction, and tongue stump mobility. OBJECTIVES: To evaluate the speech intelligibility of patients undergoing total, subtotal, or partial glossectomy, before and after speech therapy. PATIENTS AND METHODS: Twenty-seven patients (24 men and 3 women), aged 34 to 77 years (mean age, 56.5 years), underwent glossectomy. Tumor stages were T1 in 3 patients, T2 in 4, T3 in 8, T4 in 11, and TX in 1; node stages, N0 in 15 patients, N1 in 5, N2a-c in 6, and N3 in 1. No patient had metastases (M0). Patients were divided into 3 groups by extent of tongue resection, ie, total (group 1; n = 6), subtotal (group 2; n = 9), and partial (group 3; n = 12). Different phonological tasks were recorded and analyzed by 3 experienced judges, including sustained 7 oral vowels, vowel in a syllable, and the sequence vowel-consonant-vowel (VCV). The intelligibility of spontaneous speech (sequence story) was scored from 1 to 4 in consensus. All patients underwent a therapeutic program to activate articulatory adaptations, compensations, and maximization of the remaining structures for 3 to 6 months. The tasks were recorded after speech therapy. To compare mean changes, analyses of variance and Wilcoxon tests were used. RESULTS: Patients of groups 1 and 2 significantly improved their speech intelligibility (P<.05). Group 1 improved vowels, VCV, and spontaneous speech; group 2, syllable, VCV, and spontaneous speech. Group 3 demonstrated better intelligibility in the pretherapy phase, but the improvement after therapy was not significant. CONCLUSIONS: Speech therapy was effective in improving speech intelligibility of patients undergoing glossectomy, even after major resection. Different pretherapy ability between groups was seen, with improvement of speech intelligibility in groups 1 and 2. The improvement of speech intelligibility in group 3 was not statistically significant, possibly because of the small and heterogeneous sample.

Adult↗
PubMed1991

Biological factors and psychometric intelligence: a review.

Results from a synthesis of correlations between psychometric intelligence and two physical traits, head size and body size, are reported. Within-family studies are reviewed for evidence of pleiotropy, the effect of a single genetic factor on two traits. Studies are also reviewed to determine whether prenatal effects bias twin studies, leading to underestimates of genetic influence. An N-weighted mean partial correlation (controlling height) of .10 between intelligence and head size was found. Using a method developed by Van Valen (1974), the correlation of intelligence and brain size was estimated as .29 based on all the intelligence/head-size studies of adults and adolescents, and .44 based on studies measuring intelligence with IQ tests. The N-weighted mean partial correlations (controlling age) of intelligence and height were .18 for children and .22 for adults. The within-family studies indicated that pleiotropy may contribute to the correlation of intelligence with head size and to the correlation of intelligence with body size. Prenatal effects are not an important source of bias in twin studies or for heritability estimates based on them.

Adolescent↗
PubMed1996

A procedure for testing speech intelligibility in a virtual listening environment.

OBJECTIVE: The development of a test of virtual speech intelligibility in noise that enables assessment in typical, everyday listening situations. To eliminate extraneous confounding factors, digital signal processing was incorporated to simulate listening environments and source locations and allow presentation of stimuli via earphones. DESIGN: Source-to-eardrum transfer functions measured on KEMAR for various source locations in anechoic and reverberant environments were used to process monosyllabic words and speech-spectrum noise. Speech intelligibility was measured for three speech and noise configurations in two environments using an adaptive procedure to determine the signal-to-noise (S/N) ratio for 50% intelligibility. RESULTS: Normal-hearing listeners achieved 50% intelligibility of monosyllabic words at significantly lower S/N ratios in a virtual anechoic environment than in a virtual reverberant environment. Speech intelligibility improved significantly in both environments when the speech and noise sources were separated, but the intelligibility gain in the anechoic environment was four times larger than in the reverberant environment. CONCLUSIONS: This test is easy to administer and score, and it provides a means for measuring: 1) the effects of separating speech and noise sources and 2) the effects of reverberation on speech intelligibility in noise while eliminating confounding factors such as calibration.

Hearing↗
PubMed2000

Reverberation time and maximum background-noise level for classrooms from a comparative study of speech intelligibility metrics.

Speech intelligibility metrics that take into account sound reflections in the room and the background noise have been compared, assuming diffuse sound field. Under this assumption, sound decays exponentially with a decay constant inversely proportional to reverberation time. Analytical formulas were obtained for each speech intelligibility metric providing a common basis for comparison. These formulas were applied to three sizes of rectangular classrooms. The sound source was the human voice without amplification, and background noise was taken into account by a noise-to-signal ratio. Correlations between the metrics and speech intelligibility are presented and applied to the classrooms under study. Relationships between some speech intelligibility metrics were also established. For each noise-to-signal ratio, the value of each speech intelligibility metric is maximized for a specific reverberation time. For quiet classrooms, the reverberation time that maximizes these speech intelligibility metrics is between 0.1 and 0.3 s. Speech intelligibility of 100% is possible with reverberation times up to 0.4-0.5 s and this is the recommended range. The study suggests "ideal" and "acceptable" maximum background-noise level for classrooms of 25 and 20 dB, respectively, below the voice level at 1 m in front of the talker.

Humans↗
PubMed1976

Children with superior intelligence at 7 years of age: a prospective study of the influence of perinatal, medical, and socioeconomic factors.

Perinatal and medical information, growth, and the social background of 258 children who, in a prospective study, had superior intelligence at 7 years of age were reviewed. The subjects were divided into three categories on the basis of the results of psychological evaluation at age 7. Comparisons were made between those with superior (intelligence quotient greater than or equal to 120), average (IQ between 80 and 119), and low intelligence (IQ less than or equal to 79). A favorable parental social and educational background was the best correlate of superior intelligence in the children. Larger head size from 1 year of age was an early finding associated with superior intelligence. Greater height and weight, from 4 years of age were later findings. Correlations between psychological performance at ages 4 and 7 years were statistically significant. Perinatal factors and medical complications did not affect the intellectual status of children with superior intelligence.

Adolescent↗
PubMed1992

Conventional intelligence measurements and neuropsychological concepts of adaptive abilities.

The concept of intelligence and its representation by the Intelligence Quotient have been difficult to define and the subject of criticism for various reasons. Matarazzo and Kaufman have reviewed intelligence measurements and brain functions, but a biologically based explication of intelligence has not been explicitly proposed since the theories presented more than 40 years ago by Halstead and Hebb. The present study explored the overlap and differential sensitivity of intelligence measures (VIQ, PIQ, and FSIQ) and neuropsychological measures (Impairment Index and Category Test) to cerebral damage and educational attainment. The results indicated that neuropsychological measures may serve to broaden the concept of intelligence and that a brain-related criterion may contribute to a fuller understanding of its nature.

Achievement↗
PubMed1988

Intelligence of children of epileptic mothers.

Intellectual performance was investigated in a group of 148 children of epileptic mothers enrolled in a prospective study during pregnancy, and in 105 control children; 121 of the 148 children (82%) were examined together with the control group at the age of 5 1/2 years. The intelligence of 116 study and 104 control children was assessed by both verbal (Wechsler Preschool and Primary Scale of Intelligence) and nonverbal (Leiter International Performance Scale) methods. The prevalence of mental subnormality among the remaining 32 study children was calculated on the basis of psychologic assessments done outside our study, or school achievement, or both. Of the 148 study group children, 131 had been exposed in utero to antiepileptic drugs, most commonly phenytoin (103 exposed). The prevalence of mental deficiency in the study group (1.4%) was either the same or only slightly elevated in comparison with that in the general population. In the control group, there were no mentally deficient children. The mean intelligence quotients obtained at the 5 1/2-year examination were significantly lower in the study group than in the control group. There was no increased risk of low intelligence attributable to fetal exposure either to antiepileptic drugs below toxic levels or to brief maternal convulsions. In a few cases, there seemed to be a genetic connection between epilepsy in the mother and poor intellectual performance in the child. A high number of minor anomalies was associated with a lower mean intelligence quotient in both the study and the control groups. However, those features previously reported as typical of children of epileptic mothers, and those shown to be associated with phenytoin exposure in a previous phase of this study, did not predict low intelligence in the affected children.

Child, Preschool↗
PubMed1996

Breastfeeding, dummy use, and adult intelligence.

BACKGROUND: Several studies show that children who were breastfed as babies gain higher scores on intelligence tests than those who were bottlefed. Although these findings suggest that breastfeeding in early life may promote cognitive development, their interpretation is complicated by the current association between breastfeeding and higher social class. We investigated the relation between method of feeding in infancy and adult intelligence in a setting where breastfeeding was not linked with socioeconomic advantage. METHODS: We followed up 994 men and women, born between 1920 and 1930 in Hertfordshire, UK, for whom information on infant feeding had been recorded by health visitors. Intelligence was measured by the AH4 IQ test, taken on a computer. Factors significantly linked with IQ were investigated by multivariate analysis. FINDINGS: Study participants who had been exclusively breastfed gained slightly higher scores on the IQ test than those who had been exclusively bottlefed, or fed with both breast and bottle. IQ was lower in participants who had used a dummy (pacifier) in infancy, in those whose fathers were in manual occupations at the time of their birth, and in those whose mothers were young at the time they were born. Scores on the IQ test fell as the number of older siblings increased. In multivariate analysis, after adjustment for the effect of all other variables, no association was found between adult intelligence and method of feeding. Dummy use in infancy, number of older siblings, maternal age at birth of the participant, and father's occupational class remained independent predictors of adult intelligence. INTERPRETATION: The mechanisms that link type of feeding in early life with later intelligence may have more to do with the child's social environment that with the nutritional qualities of the milk.

Adult↗
PubMed1982

Changes in intelligence following temporal lobectomy: relationship to EEG activity, seizure relief, and pathology.

Pre- and posttemporal lobectomy measures of intelligence and memory in 36 patients with medically refractory complex partial seizures were compared with (1) various aspects of presurgical ictal and interictal EEG activity derived from surface and deep electrodes, (2) postlobectomy seizure relief, and (3) pathological findings in the resected lobe. With respect to interictal EEG data, bilaterally synchronous surface spikes (accompanied or unaccompanied by simultaneous deep spikes) and sharp waves were significantly correlated with lower prelobectomy intelligence scores and a drop in these scores following lobectomy. With respect to ictal EEG data, bilaterally synchronous and multifocal onsets were significantly correlated with a postlobectomy drop in intelligence scores. Patients with poor postlobectomy seizure relief tended to have lower presurgical intelligence scores and a drop in intelligence scores following lobectomy. The patients most likely to show a postlobectomy drop in intelligence were those demonstrating some combination of poor seizure relief, an absence of pathology in the resected specimen, or EEG signs indicative of poor seizure relief. Postlobectomy changes in intellectual status are therefore not necessarily exclusively attributable to the amount of postlobectomy seizure relief experienced by these patients, but might be due to a combination of factors.

Adult↗
PubMedDate not supplied

Design factors in the assessment of intelligence.

The use of intelligence tests to assess the effects of otitis media on the development of children is discussed in this article. An overview of the development of intelligence tests is provided and some of the limitations and central issues of controversy concerning intelligence testing and the IQ are reviewed. Basic intelligence tests are described in terms of their characteristics and uses; the questions which an investigator must ask about any given intelligence test measure are posed and answered. Finally, cautions concerning the applicability of intelligence tests for evaluating the effects of otitis media are offered.

Humans↗
PubMedDate not supplied

Inverse relationship between nonverbal intelligence and the parameters of pattern reversal visual evoked potentials in left-handed male subjects: importance of right brain and testosterone.

The relationships between latencies of visual evoked potentials (VEPs) and nonverbal intelligence test scores (IQs from Cattell's Culture Fair Intelligence Test) and correlations between serum testosterone level and VEP latencies were studied to examine the neural speed hypothesis of intelligence and its hormonal mechanisms in left-handed male subjects (Geschwind Scores). In accordance with the speed theory of intelligence, N1 and P1 latencies (and amplitudes) were found to be inversely related to IQ. However, this was true only for the right brain; the left brain did not contribute to this relationship. There was an inverse relationship between serum testosterone level and P1 latency; left minus right N1 latency, depending on N1 latency from right brain, linearly increased with testosterone. It was concluded that nonverbal intelligence largely depends on speed of information processing only by the right brain, not by the left brain in left-handed male subjects. This may have been created by testosterone in these subjects. Inconsistencies in the IQ literature concerning the speed hypothesis of intelligence may be explained by differences in cerebral lateralization.

Adolescent↗