Auditory Acuity Research Articles

Amplitude-modulation detection at low- and high-audio frequencies.

Estimates of temporal acuity under comparable conditions at low- and high-audio frequencies are rare. The present study used the amplitude-modulation detection paradigm to estimate temporal acuity over a range of audio frequencies from 800 to 12,800 Hz. Amplitude-modulation detection was measured as a function of modulation frequency for bandlimited noise carriers, and the resulting temporal modulation-transfer functions were used to characterize temporal acuity. The most important result from the two experiments reported is that systematic manipulations of carrier upper-cutoff frequency produced estimates of temporal acuity that did not vary from 800 to 12,800 Hz. When the modulated noise bands were filtered after modulation to control for potential spectral cues, the low-pass cutoff of the modulation-transfer function varied with the carrier bandwidth. However, when the standard stimulus was a quasifrequency-modulated (QFM) noise and the signal was an unfiltered, amplitude-modulated noise, the low-pass cutoff of the modulation-transfer function was independent of carrier bandwidth. These results are consistent with a growing body of evidence demonstrating that auditory temporal acuity is constant throughout most of the audible frequency range.

Conservative management of acoustic neurinomas: prospective study of long-term changes in tumor volume and auditory function.

Recently reported retrospective analysis on the natural courses of acoustic neurinomas have disclosed that 26-86% of tumors show very slow, or no, growth for many years. To our knowledge, however, there have been no prospective analyses of the natural course of these tumors. We prospectively analyzed tumor growth as well as auditory function changes in 12 patients (13 tumors) managed conservatively. All 12 patients were advised to undergo both pure tone audiometry and magnetic resonance imaging at 3-4 month intervals for the first follow-up year and at 1-2 year intervals thereafter. Then, in the event of either significant tumor growth (> 20% volume increase) or hearing deterioration (> 10 dB), a decision would be made as to whether the patient should undergo either surgery or radiosurgery. A significant increase in tumor volume was confirmed in seven of the 13 tumors during the mean observation period of 564 days (88-1269 days). In another patient, though neither tumor growth nor worsening of auditory acuity was significant, the patient complained of subjective change in the symptoms. Therefore, we decided to treat eight (62%) of the 13 tumors. In contrast, neither tumor growth nor worsening of auditory acuity has as yet occurred in the remaining five tumors (38%) which have been observed for a mean period of 627 days (342-1377 days). Careful follow-up of these five patients is ongoing. Although further long-term follow-up is clearly necessary, conservative treatment appears to be a reasonable alternative to immediate treatment for selected patients with acoustic neurinomas.

Which Korotkoff sound should be used for the diastolic blood pressure in pregnancy?

There is a gathering momentum favouring the adoption of the 5th Korotkoff sound to identify diastolic blood pressure in pregnancy. Our objective was to measure interobserver reliability for indirect blood pressure measurement in pregnancy for systolic and diastolic measurements and to calculate the difference in diastolic pressure measured by the 4th and 5th Korotkoff sounds. To minimize bias we used trained but previously inexperienced observers with proven, normal auditory acuity. The observers were paired in 4 teams and performed a series of 334 blinded, simultaneous observations of systolic and diastolic blood pressure measurements taken from pregnant women between 12-41 weeks' gestation. Reliability was measured by intraclass correlation coefficient for paired measures and kappa for the detection or nondetection of 4th (K4) and 5th (K5) Korotkoff sounds. K4 was undetected in 36% of observations and K5 was undetected in 2% of observations. Reliability for detection or nondetection of Korotkoff sounds was fair for K4 (kappa 0.36) and moderate for K5 (kappa 0.58). Reliability was good between observers for systolic, K4 and K5 diastolic measurements (intraclass correlation > or = 0.80). The mean difference between the diastolic pressure measured by K4 and K5 was 15 mmHg for all measurements and 8 mmHg for the top quartile of measurements (p <0.001). We found K5 to be more often and more reliably detected than K4. If units adopt K5 in preference to K4, consideration will need to be given to lowering treatment thresholds for women with borderline or mild hypertension.

Speech perception in children with specific reading difficulties (dyslexia).

Many experimental studies over the last two decades have suggested that groups of children who suffer significant delay in reading also show a weakness in phoneme discrimination and identification. In order to look further at the relation between type of reading deficit, auditory acuity, and speech discrimination, a group of 13 children with specific reading difficulty (SRD), 12 chronological-age controls, and 12 reading-age controls were tested on a battery of speech-perceptual, psychoacoustic, and reading tests. A sub-group of children with Specific Reading Difficulty (SRD) were poor at speech discrimination tests, whereas the rest of the SRD group performed within norms. For this sub-group, discrimination performance was particularly poor for consonant contrasts differing in a single feature that was not acoustically salient, and problems were encountered with nasal and fricative contrasts as wells with stop contrasts. These children did not differ from controls in their performance on non-speech psychoacoustic tasks. An evaluation is made of the reported phonemic awareness skills of beginning readers with regard to speech-processing issues which may help in understanding what factors are important in reading development.

実験的プロブスト交連切断後の行動学的変化

Albino rats were tested for their ability to localize sounds in space and for their reflex head orientation to auditory stimulation before and after a micro knife transection of the commissure of Probst. The animals were trained to approach a sound source on a two choice test apparatus in order to obtain a water reward. The minimum audible angles were then determined for midline (left vs. right) sound localization using the method of descending limits to define the thresholds for auditory spatial acuity. The commissure of Probst was then transected through its midline decussation with a micro knife inserted into the brain according to stereotaxic coordinates. Following a postoperative recovery period of at least one week, the rats were retrained and again tested for sound localization. After completing the sound localization tests, the animals were tested for reflex head orientation with a single burst of 70dB (SPL) broad-band noise. In most cases, the lesions were within 200-300 microns of the midline, and damage at locations lateral to the knifecut was very slight. The condition of the damaged fibers was confirmed by both anterograde and retrograde tract tracing methods. After a complete transection of the commissure of Probst, the number of cell bodies in the dorsal nucleus of the lateral lemniscus (DNLL) was greatly reduced. Most of the contralaterally projecting neurons in the DNLL underwent retrograde degeneration. Complete transection of the commissure of Probst resulted in elevated behavioral thresholds for midline sound localization. The minimum audible angles were elevated, and reflex head movements towards the sound source were abolished in most animals with extensive lesions. These results suggest that the Commissure of Probst fibers, including the crossed projections from the DNLL, play a role in auditory spatial perception, especially in the ability to discriminate small auditory angles. These projections also appear to play an important role in the reflex pathway for auditory head orientation.

From good senses to good sense: A link between tactile information processing and intelligence

Since the 1970s there has been an reemerging interest in Galton's (1883) senses-intelligence hypothesis. The essence of this hypothesis is the conceptual link between fine-tuned sensory functioning and superior intellectual ability. Several studies have investigated the sensory-cognitive link within auditory and visual modalities. In this study, the intersystemic relationship between sensory and cognitive functioning was extended to the tactile modality by examining the associations between three measures of tactile information processing and intelligence in a heterogeneous sample of middle-aged adults (N = 179; age range = 30–51). Two of the three tactile tasks measured discrimination ability (i.e., roughness discrimination and part-whole matching), whereas the third task measured tactile pressure sensitivity. Results from a series of analyses indicate that sensory measures from the tactile modality are at least as highly correlated with intellectual ability ( r = .18 to .33) as measures of auditory ( r = .15) or visual ( r = .20) acuity. All together, the three tactile measures accounted for 20.8% of the total variance in intelligence. The two tactile discrimination measures were found to be better predictors of intelligence than measures of simple sensory acuity.

Medical Surveillance of HAZMAT Response Fire Fighters

The Authors Reply: Thank you for the opportunity to respond to Dr Tubbs' letter. We agree with Dr Tubbs that the use of hearing-protective devices during transport can be a valuable part of a hearing conservation program for fire fighters. We appreciate that he brought this fact to the attention of the Journal's readers. We certainly did not "rule out" the use of hearing-protective devices nor imply that they are inappropriate for fire fighters in all situations. However, it must be recognized that fire fighters' noise exposures are not limited to transport and continue to some extent at fires and chemical accidents where decreasing one's auditory acuity can have adverse effects on safety and performance. Our discussion simply emphasized our preference for reducing exposures through engineering controls. Dr Tubbs' own chapter1 (cited in his letter) also discusses various engineering changes that can reduce fire fighters' noise exposures at their sources. In conclusion, we support both hearing-protective devices and engineering controls as components of comprehensive hearing conservation programs for fire fighters. Stephen N. Kales, MD, MPH Harvard Medical School; Boston, MA David C. Christiani, MD, MPH, MS Harvard School of Public Health; Boston, MA

Dietary, anthropometric, hematological and biochemical assessment of the nutritional status of centenarians and elderly people in Okinawa, Japan.

The population of old people has increased and nutritional disorders are common among them. The assessment of nutritional status and dietary intakes of this population is necessary in order to improve their nutritional status and reduce risk to infection and mortality. In the present study, data on the nutritional status of healthy elderly and centenarians is provided.Participants were free-living healthy volunteers (39 centenarians; 11 male and 28 female and 44 elderly in their 70s; 13 male and 31 female).Their nutritional status was assessed by anthropometric measurements, hematological and biochemical variables. Activities of daily living (ADL) of 11 items were scored depending upon their activities with a maximum score of 5.0. Dietary survey by food recording was done for 2 days and food models were used to obtain the best estimate of food intake. Energy and nutrient intakes were compared with Japanese recommended dietary allowances (RDAs).The elderly had complete independence of physical activities, good sensory function and cognitive abilities. The physical activities of male centenarians were between the category of completely independent and independent but slow. In female centenarian participants, their physical activities were independent but slow or independent with difficulty. The functions of auditory acuity and eyesight of the centenarians were poor but their cognitive abilities were still good. The elderly subjects had short stature whereas their body weight and body mass index (BMI) were not low, especially among the women, compelling female elderly to reduce their food intake to control the weight. Energy intake of female centenarians was low. The ADL in the female centenarians was positively related to energy, suggesting that the low energy intake of the female centenarians was mainly due to their low ADL. Anthropometric, hematological and biochemical variables of the centenarians were lower or near the lower reference limit except serum lipids. All the hematological and biochemical variables were statistically lower (p < 0.05) in the centenarians than in the elderly particularly for females with some minor exceptions.The results of the present study showed that the nutritional status assessed by ADL and anthropometric, hematological and biochemical parameters was poor in the centenarian subjects but was maintained in the elderly subjects except height and that the diet was not the major factor of their problems in the nutritional status.

Auditory localization acuity in free field and simulated environments: Reaction time measures

A reaction time measure was used to compare localization acuity in a free field and a simulated environment (where headphone-presented stimuli are processed so as to approximate the waveforms that would occur at each ear canal for a free-field source). Four listeners discriminated the relative direction of a broadband noise (whether it was to the left or right of midline or whether it was in front or back of the interaural axis). The results across four listeners demonstrated that psychometric functions could be plotted for both reaction time as well as percent correct versus angle. Localization was better in the free-field conditions (higher percent correct scores as well as faster reaction times) for front–back discrimination; however, the free-field advantage was negligible for left–right discrimination. Under headphone presentation, there was large inter-subject variability in reaction times for front–back discrimination, but not for left–right discrimination. Although the above findings were not especially surprising, the two metrics did mirror one another in a predictable fashion. The strengths of each procedure will be discussed. [Work supported by NMRDC and ONR, 61153N.MR04101.OOH-5601.]

Genetic studies of specific language impairment

Specific Language Impairment (SLI) is a form of developmental dysphasia which reportedly aggregates in families. This report: 1. (1) reviews classical and recent evidence which strongly supports the hypothesis that heritable factors are, at least in part, responsible for familial aggregation of SLI; 2. (2) presents preliminary clinical and phenotypic data from one cohort set appropriate for linkage analysis; and 3. (3) discusses these findings within the context of recent progress in the field of human behavioral (and especially psychiatric) genetics. Our preliminary data confirm familial clustering of SLI; 55.8% of 95 probands had at least one affected 1 ° or 2 ° relative, and 21 families met stringent criteria for multigenerational impairment. These multigenerational kindreds, as well as several additional sets of sibling pairs, are suitable for planned linkage analysis of this trait. There was a trend toward cosegregation of putative phenotypic subtypes within kindreds. However, many cases fell near the boundary of the usual exclusionary criteria, and displayed borderline IQ, borderline auditory acuity or symptoms of attentional disorder or autism insufficient to meet diagnostic criteria. The possibility that one or more of these phenotypic subtypes will be useful for future linkage analysis remains to be evaluated.

Emergence of a powerful connection between sensory and cognitive functions across the adult life span: a new window to the study of cognitive aging?

Six hundred eighty seven individuals ages 25-103 years were studied cross-sectionally to examine the relationship between measures of sensory functioning (visual and auditory acuity) and intelligence (14 cognitive tasks representing a 5-factor space of psychometric intelligence). As predicted, the average proportion of individual differences in intellectual functioning connected to sensory functioning increased from 11% in adulthood (25-69 years) to 31% in old age (70-103 years). However, the link between fluid intellectual abilities and sensory functioning, albeit of different size, displayed a similarly high connection to age in both age groups. Several explanations are discussed, including a "common cause" hypothesis. In this vein, we argue that the increase in the age-associated link between sensory and intellectual functioning may reflect brain aging and that the search for explanations of cognitive aging phenomena would benefit from attending to factors that are shared between the 2 domains.

Everyday activity patterns and sensory functioning in old age.

In the present study the authors investigated the relationship between visual and auditory acuity and everyday activity functioning. Participants were 516 older adults (70-103 years; equal numbers of men and women) who were members of the age-stratified Berlin Aging Study. Two categories of everyday activity functioning, perceived competence with basic activities of daily living (BaCo; basic competence) and amount of participation in discretionary social and leisure tasks (ExCo; expanded competence), were examined. The results revealed that sensory acuity, particularly vision, was a significant predictor of both BaCo and ExCo (rs ranging from .32 to .47). Indeed, hearing and vision could explain most of the age-related variance in everyday activities. At the same time, in the context of a broader model, evidence for the differential prediction of BaCo and ExCo was found, although there was also evidence for strong general age-related predictive variance that was common to both measures. Discussion focuses on the role of sensory acuity constructs as mediators of age-related variance in psychological and behavioral outcomes and the potential causal implications of this mediation.

Effects of Prenatal Alcohol Exposure and Aging on Auditory Function in the Rat: Preliminary Results

This study investigated select aspects of peripheral and central auditory dysfunction, as well as the pathological effects of aging, In an animal model of fetal alcohol syndrome (FAS). Pregnant rats consumed liquid alcohol diets containing 0, 17.5, or 35% ethanol-derived calories, from gestation day 7 to parturition. A fourth group was untreated. Offspring of these mothers were tested for auditory and neurological function, using the auditory brainstem response at 6, 12, and 18 months of age. Some animals in the alcohol-exposed groups showed a peripheral auditory disorder in the form of congenital sensorineural hearing loss. This was correlated with punctate lesions and malformed stereocilia on the auditory sensory receptor cells of the inner ear. Alcohol-exposed animals also showed a central auditory processing disorder characterized by prolonged transmission of neural potentials along the brainstem portion of the auditory pathway. Animals in the highest dose group also showed an augmentation in the age-related deterioration of auditory acuity. Thus, increased peripheral and central auditory dysfunctions and pathological deterioration of auditory function in old age may be sequelae of FAS. Such morbidities have important implications for the long-term clinical assessment and management of FAS patients.

Biosocial variables and auditory acuity as risk factors for non-fatal childhood injuries in Greece.

To examine whether biosocial variables and auditory acuity are risk factors for injuries among children. Children with injuries who presented at the emergency clinics of one of the two university hospitals for children in Athens, Greece between December 1993 and April 1994. 144 children aged 5-14 years, residents of Athens, were brought to the emergency clinics for a moderate to severe injury. For each of these children one hospital control, matched for age and sex, and one classmate control similarly matched were identified. A standard interview form was completed for all 432 children and acouometric and tympanometric examinations were performed in each of them. Analysis was done through conditional logistic regression. The likelihood of an accident was higher in children of younger fathers (odds ratio (OR) = 0.7, p = 0.04), children of mothers with non-professional jobs (OR = 1.9, p = 0.03) as well as in children of higher birth order (OR = 1.7, p = 0.01), in those with predominantly other than parental daily supervision (OR = 2.6, p = 0.001), and those with a history of previous accident (OR = 1.3, p = 0.002). Somatometric factors, school performance, use of corrective eyeglasses and subnormal auditory acuity were not found to be risk factors, but auditory imbalance and abnormal tympanograms were positively related to the risk of childhood injury (OR = 2.6, p = 0.02; and OR = 2.3, p = 0.08 respectively). the findings of this study underline the importance of attentive supervision and safety training of children living in modern cities; they also suggest that children with auditory imbalance and history of an accident are at higher injury risk and they should be targeted with specific intervention programs.

Vibroacoustic Stimulation and Auditory Acuity in Preterm Infants

Vibroacoustic stimulation (VAS) is widely accepted as a simple and inexpensive adjunctive antenatal test for fetal well-being. However, possible adverse effects of VAS on auditory acuity are not completely known and are of concern, especially for infants delivered prematurely. The purpose of our study was to evaluate neonatal hearing with the brain stem auditory evoked response (BAER) in 33 preterm neonates exposed to acoustic stimulation in utero and to compare the results with those of 33 preterm neonates who were not exposed to acoustic stimulation. Of the 33 exposed neonates, four had abnormal BAER results, indicating an apparent hearing loss. In three of four cases, an infectious etiology was found, suggesting a lack of association between antenatal VAS and hearing loss. By comparison, of the 33 preterm infants not exposed to VAS antenatally (control group), one infant had an abnormal BAER result and was subsequently diagnosed to have suffered a congenital hearing loss.Thus, the risk of acoustic trau...

Chronological study concerning ADL among Okinawan centenarians

Since 1976 medicobiological and sociological surveys have been carried out upon centenarians in Okinawa. Recently dementia and disability have increased among centenarians. In order to determine the statistical significance, ADL (Activities of Daily Living) scores among Okinawan centenarians were compared; 43 subjects were studied from the 1970's (1976-1980), 99 subjects from the 1980's (1986-1988), and 109 subjects from the 1990's (1992-1994). ADL scores of each centenarian were recorded by the same researchers at the University of the Ryukyus Hospital, based on observation and examination of the centenarians where they lived. Five categories of self sufficiency were defined; completely independent, independent but slow, independent with difficulty, partially dependent, and completely dependent. There were seven physical tasks scored; taking meals, bowel and bladder continence, ability to rise from a toilet, ability to stand, extent of general activities, ability to bathe, and ability to dress oneself. Their sensory functions (auditory acuity and eyesight) and cognitive abilities (comprehension and self-expression) were also scored. Declining rates of total ADL scores were more marked between the 1970's and the 1980's than between the 1980's and the early 1990's. It was also more remarkable in institutionalized centenarians than in centenarians living at home. Decline in physical activities was more distinct in institutionalized than in home-living centenarians. On the other hand, cognitive abilities declined more among centenarian living at home than among institutionalized centenarians. The population of centenarians has increased 23 times over the past 22 years in Okinawa. Human life span has been remarkably extended by advanced medical technology, physically easier life style, and improvement in overall social welfare.(ABSTRACT TRUNCATED AT 250 WORDS)

Relationships between hearing and auditory cognition in Down syndrome youth

Twenty-six adolescents and young adults with Down syndrome and 26 IQ- and CA-matched youth with other causes of intellectual impairment (comparison group) repeated a battery of audiological and auditory-cognitive tests on three annual assessments. Audiological tests revealed the following differences between the group with Down syndrome and the comparison group: a) Poorer acuity and longitudinal declines at each frequency from 250-8000 Hz for the group with Down syndrome, particularly at the highest frequencies; b) A tendency for the middle ear problems of Down syndrome individuals to be bilateral, chronic, and to reflect no mobility, retraction, or reduced mobility of the tympanic membrane; and c) Poorer reception and discrimination of speech in the group with Down syndrome. Correlational analyses revealed the following reliable relationships between performance on audiological and auditory-cognitive tests: a) individuals with Down syndrome who had lower speech discrimination scores, poorer acoustic reflexes, or bilaterally impaired tympanograms repeated spoken sentences less accurately; b) individuals with Down syndrome who had lower speech discrimination scores performed more poorly on a language comprehension task; and c) individuals with Down syndrome with impaired hearing (regardless of how it was measured) identified fewer spoken words when the words were rapidly followed by a masking noise or made discriminable by brief consonant sounds. It was suggested that poorer performance by hearing-impaired subjects with Down syndrome on auditory-cognitive tasks may have been due to an interaction of lower auditory acuity and slower processing speed. Also, because relationships between hearing and cognitive variables were not present in the comparison group, it was tentatively suggested that hearing loss may be more detrimental to cognitive abilities in intellectually impaired individuals with Down syndrome.

Brainstem auditory evoked potentials characteristics in mice: The effect of genotype

Brainstem auditory evoked potentials (BAEPs) elicited by sound clicks were recorded as a function of stimulus intensity in pentobarbital anesthetized C57BL/6J and BALB/c male mice, 2.5 months old. At high stimulus intensities the BAEPs of both strains consisted of 4 positive and 4 negative waves (labelled P1-P4 and N1-N4, correspondingly). However, great interstrain differences were observed. BALB/c mice were characterized by higher thresholds, less amplitudes, beginning with P1 peak, longer latencies and steeper in slope latency-intensity profiles. The data suppose that by this age C57BL/6J mice have better auditory acuity, than BALB/c, and in BALB/c mice the pronounced abnormalities appear to arise in cochlear-auditory nerve system. Analysis of BAEPs using interpeak latencies (IPLs) and amplitude ratios intensities (ARs) profiles technique demonstrated no general trend that could fit for all IPLs as well as for all Ars changes by varying stimulus intensity. The obtained interstrain and interpeak differences in BAEPs parameters suggest that auditory information processing may vary greatly as a function of brainstem level.

Fluctuating and/or progressive sensorineural hearing loss in children

Sensorineural hearing loss (SNHL) which is sudden in onset, fluctuating, and/or progressive complicates medical management, hearing aid selection, and individualized educational planning for a hearing-impaired child. In spite of multidisciplinary evaluation and intervention, a gradual decrease in auditory acuity may continue unabated in a significant number of cases. Intercurrent middle ear disease and inconsistent audiologic technique can account for threshold variation in some cases. The study population consisted of 229 children (132 boys; 97 girls) aged 1 to 19.9 years at first audiogram which revealed at least a mild degree of sensorineural hearing loss in one or both ears (35 unilateral), and who demonstrated threshold variation of 10 dB or more in at least one ear at one or more of the standard audiometric test frequencies (250, 500, 1000, 2000, 4000, and 8000 Hz) and were without concurrent middle ear disease (mean length of follow-up, 4.9 years; mean number of audiograms, 10.3). Of 365 ears demonstrating threshold variation of 10 dB or more, 22 (6%) had purely progressive losses without intercurrent upward fluctuation, 208 (57%) had fluctuating thresholds with gradually progressive losses, and 135 (37%) had intermittent threshold fluctuation without permanent deterioration. The probability of contralateral threshold fluctuation if one ear fluctuated was 0.91, while the probability of contralateral progressive SNHL if one ear progressed was 0.67. Demographic data, presumptive etiology, degree of initial SNHL, audiometric configuration, and symmetry of threshold variation were considered as potential predictors of the likelihood of threshold fluctuation and/or progression.

Sensory functioning and intelligence in old age: a strong connection.

Relations among age, sensory functioning (i.e., visual and auditory acuity), and intelligence were examined in a heterogeneous, age-stratified sample of old and very old individuals (N = 156, M age = 84.9 years, age range = 70-103). Intelligence was assessed with 14 tests measuring 5 cognitive abilities (speed, reasoning, memory, knowledge, and fluency). Together, visual and auditory acuity accounted for 49.2% of the total and 93.1% of the age-related reliable variance in intelligence. The data were consistent with structural models in which age differences in intelligence, including speed, are completely mediated by differences in vision and hearing. Results suggest that sensory functioning is a strong late-life predictor of individual differences in intellectual functioning. Explanations are discussed, including the possibility that visual and sensory acuity are indicators of the physiological integrity of the aging brain (common cause hypothesis).