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Biomedical subjects

M S Sommers

Publications and source records attributed to M S Sommers.

At least 19 recordsLinked to original sources
PubMed1998

Auditory suppression and frequency selectivity in older and younger adults.

Age differences in auditory suppression were examined by comparing auditory-filter shapes obtained with simultaneous and forward masking at 2 kHz in young and elderly normal-hearing listeners. To compensate for the decay of forward masking, growth of masking functions were used to transform thresholds obtained with a notched-noise masker to the level of a continuous noise band that would give the same threshold values. Although both age groups exhibited smaller equivalent rectangular bandwidths (ERBs) when the filters derived from transformed thresholds were obtained with forward masking, the change from simultaneous to nonsimultaneous masking was significantly greater for young adults. Measures of the low- (Pl) and high- (Pu) frequency sides of the filters for young listeners indicated that the slopes of both sides increased following a change from simultaneous to forward masking but that the high-frequency side exhibited significantly greater sharpening. Filter slopes (both upper and lower) for older adults, in contrast, did not differ between the two masking procedures. The findings from the study are discussed as reflecting possible age differences in auditory suppression. However, it is also noted that conclusions regarding differences between filter shapes derived with simultaneous and forward masking are limited to filter parameters determined with transformed (as described above) thresholds.

Adolescent↗
PubMed1998

Brief intervention after alcohol-related injuries.

Brief intervention is a clinically-based, cost effective, time efficient intervention designed to counsel nondependent drinkers about strategies to reduce their alcohol consumption. The ultimate goal of brief intervention is to prevent future alcohol-related injury and health problems. This focused and time limited intervention is designed for use by health care providers in their ongoing daily practice. Patients who recently experienced an alcohol-related injury are particularly receptive to brief intervention.

Alcoholism↗
PubMed1997

Some considerations in evaluating spoken word recognition by normal-hearing, noise-masked normal-hearing, and cochlear implant listeners. I: The effects of response format.

OBJECTIVE: The purpose of the present studies was to assess the validity of using closed-set response formats to measure two cognitive processes essential for recognizing spoken words---perceptual normalization (the ability to accommodate acoustic-phonetic variability) and lexical discrimination (the ability to isolate words in the mental lexicon). In addition, the experiments were designed to examine the effects of response format on evaluation of these two abilities in normal-hearing (NH), noise-masked normal-hearing (NMNH), and cochlear implant (CI) subject populations. DESIGN: The speech recognition performance of NH, NMNH, and CI listeners was measured using both open- and closed-set response formats under a number of experimental conditions. To assess talker normalization abilities, identification scores for words produced by a single talker were compared with recognition performance for items produced by multiple talkers. To examine lexical discrimination, performance for words that are phonetically similar to many other words (hard words) was compared with scores for items with few phonetically similar competitors (easy words). RESULTS: Open-set word identification for all subjects was significantly poorer when stimuli were produced in lists with multiple talkers compared with conditions in which all of the words were spoken by a single talker. Open-set word recognition also was better for lexically easy compared with lexically hard words. Closed-set tests, in contrast, failed to reveal the effects of either talker variability or lexical difficulty even when the response alternatives provided were systematically selected to maximize confusability with target items. CONCLUSIONS: These findings suggest that, although closed-set tests may provide important information for clinical assessment of speech perception, they may not adequately evaluate a number of cognitive processes that are necessary for recognizing spoken words. The parallel results obtained across all subject groups indicate that NH, NMNH, and CI listeners engage similar perceptual operations to identify spoken words. Implications of these findings for the design of new test batteries that can provide comprehensive evaluations of the individual capacities needed for processing spoken language are discussed.

Adult↗
PubMed1997

Speech perception in older adults: the importance of speech-specific cognitive abilities.

OBJECTIVE: To provide a critical evaluation of studies examining the contribution of changes in language-specific cognitive abilities to the speech perception difficulties of older adults. DESIGN: A review of the literature on aging and speech perception. CONCLUSIONS: The research considered in the present review suggests that age-related changes in absolute sensitivity is the principal factor affecting older listeners' speech perception in quiet. However, under less favorable listening conditions, changes in a number of speech-specific cognitive abilities can also affect spoken language processing in older people. Clinically, these findings suggest that hearing aids, which have been the traditional treatment for improving speech perception in older adults, are likely to offer considerable benefit in quiet listening situations because the amplification they provide can serve to compensate for age-related hearing losses. However, such devices may be less beneficial in more natural environments, (e.g., noisy backgrounds, multiple talkers, reverberant rooms) because they are less effective for improving speech perception difficulties that result from age-related cognitive declines. It is suggested that an integrative approach to designing test batteries that can assess both sensory and cognitive abilities needed for processing spoken language offers the most promising approach for developing therapeutic interventions to improve speech perception in older adults.

Aged↗
PubMed1997

Stimulus variability and spoken word recognition. II. The effects of age and hearing impairment.

Three experiments were conducted to investigate the effects of variations in talker characteristics, speaking rate, and overall amplitude on perceptual identification in normal-hearing young (NHY), normal-hearing elderly (NHE), and hearing-impaired elderly (HIE) listeners. The three dimensions were selected because variations in voice characteristics and speaking rate affect features of speech signals that are important for word recognition while overall amplitude changes do not alter stimulus parameters that have direct effects on phonetic identification. Thus, the studies were designed to examine how variations in both phonetically relevant and irrelevant stimulus dimensions affect speech processing in a number of different populations. Age differences, as indicated by greater effects of variability for the NHE compared with the NHY listeners, were observed for mixed-talker and mixed-amplitude word lists. Effects of age-related hearing impairment, as indicated by reduced scores for the HIE compared with the NHE group, were observed for variations in speaking rate and talker characteristics. Considered together, the findings suggest that age-related changes in perceptual normalization and selective attention may contribute to the reduced speech understanding that is often reported for older adults.

Aging↗
PubMed1996

The structural organization of the mental lexicon and its contribution to age-related declines in spoken-word recognition.

Three experiments were conducted within the framework of the Neighborhood Activation Model of spoken-word recognition to study how the structural organization of the mental lexicon may contribute to age-related declines in spoken-language processing. Experiment 1 showed that the number and frequency of words that are phonetically similar to a target word had differential effects on perceptual identification in older and younger adults, with older adults being particularly disadvantaged in identifying hard words (words phonetically similar to many other high-frequency words). Experiment 2 showed that age-related deficits in the ability to identify hard words remained under conditions in which performance for a set of easy words (items phonetically similar to relatively few other low-frequency words) was the same for older and younger adults. In Experiment 3, reducing the resources available for identification by changing from single to multiple talkers reduced word recognition more among older than younger adults. Diminished cognitive resources, impaired inhibitory control, and increased general slowing are discussed as explanations for the results.

Adolescent↗
PubMed1996

Modeling formant frequency discrimination of female vowels.

The present investigations were designed to establish the features of vowel spectra that mediate formant frequency discrimination. Thresholds for detecting frequency shifts in the first and second formants of two steady-state vowels were initially measured for conditions in which the amplitudes of all harmonics varied in accordance with a model of cascade formant synthesis. In this model, changes in formant frequency produce level variations in components adjacent to the altered formant as well as in harmonics spectrally remote from the shifted resonant frequency. Discrimination thresholds determined with the cascade synthesis procedure were then compared to difference limens (DLs) obtained when the number of harmonics exhibiting level changes was limited to the frequency region surrounding the altered formant. Results indicated that amplitude variations could be restricted to one to three components near the shifted formant before significant increases in formant frequency DLs were observed. In a second experiment, harmonics remote from the shifted formant were removed from the stimuli. In most cases, thresholds for these reduced-harmonic complexes were not significantly different from those obtained with full-spectrum vowels. Preliminary evaluation of an excitation-pattern model of formant frequency discrimination indicated that such a model can provide good accounts of the thresholds obtained in the present experiments once the salient regions of the vowel spectra have been identified. Implications of these findings for understanding the mechanism mediating vowel perception are discussed.

Auditory Threshold↗
PubMed1995

Brief intervention as an advanced practice strategy for seriously injured victims of multiple trauma.

Trauma is the leading cause of death during the first 4 decades of life. Approximately 40-50% of seriously injured patients who require hospitalization have an alcohol-related injury. The traumatic injury offers nurses in advanced practice roles a unique opportunity to discuss the relation between the patients' traumatic injuries and their alcohol use. One strategy that has shown promise in recent research is the Brief Intervention, a simple and quick clinical tool used to motivate patients to consider the consequences of their alcohol-related behavior. The Brief Intervention technique uses a screening instrument, the Alcohol Use Disorders Test, to determine whether the patient is a sensible, heavy, or dependent drinker. A counseling session, focusing on reducing alcohol use in the nondependent drinker, follows while the patient is still acutely injured. Through the use of Brief Intervention, the nurse has an opportunity to motivate trauma patients to change their patterns of drinking and limit their risk for repeated injuries. If nurses can prevent future injuries, the potential savings in lives lost and dollars spent are huge.

Alcoholism↗
PubMed1995

Skin temperature and limb blood flow as predictors of cardiac index.

Thermodilution cardiac output and cardiac index (CI) require inserting a pulmonary artery catheter, an invasive device associated with many iatrogenic complications. The purpose of this study was to establish the concurrent validity of two noninvasive measures of CI (skin temperature and limb blood flow) by determining their correlation with invasive CI. Twenty-one subjects undergoing coronary artery bypass grafting (CABG) were studied every 2 hours for 8 hours in the immediate postoperative period. Neither limb blood flow (LBF) nor skin temperature at five sites correlated significantly (p < .05) with CI at all five data collection times. Ankle temperature and LBF were significantly correlated with CI at one data collection time. On the basis of the findings of this study, neither skin temperature nor LBF can be used as a noninvasive predictor of CI in the immediate postoperative period following CABG.

Adult↗
PubMed1995

Effects of stimulus variability on perception and representation of spoken words in memory.

A series of experiments was conducted to investigate the effects of stimulus variability on the memory representations for spoken words. A serial recall task was used to study the effects of changes in speaking rate, talker variability, and overall amplitude on the initial encoding, rehearsal, and recall of lists of spoken words. Interstimulus interval (ISI) was manipulated to determine the time course and nature of processing. The results indicated that at short ISIs, variations in both talker and speaking rate imposed a processing cost that was reflected in poorer serial recall for the primary portion of word lists. At longer ISIs, however, variation in talker characteristics resulted in improved recall in initial list positions, whereas variation in speaking rate had no effect on recall performance. Amplitude variability had no effect on serial recall across all ISIs. Taken together, these results suggest that encoding of stimulus dimensions such as talker characteristics, speaking rate, and overall amplitude may be the result of distinct perceptual operations. The effects of these sources of stimulus variability in speech are discussed with regard to perceptual saliency, processing demands, and memory representation for spoken words.

Female↗
PubMed1995

New directions for assessing speech perception in persons with sensory aids.

This study examined the influence of stimulus variability and lexical difficulty on the speech perception performance of adults who used either multichannel cochlear implants or conventional hearing aids. The effects of stimulus variability were examined by comparing word identification in single-talker versus multiple-talker conditions. Lexical effects were assessed by comparing recognition of "easy" words (ie, words that occur frequently and have few phonemically similar words, or neighbors) with "hard" words (ie, words with the opposite lexical characteristics). Word recognition performance was assessed in either closed- or open-set response formats. The results demonstrated that both stimulus variability and lexical difficulty influenced word recognition performance. Identification scores were poorer in the multiple-talker than in the single-talker conditions. Also, scores for lexically "easy" items were better than those for "hard" items. The effects of stimulus variability were not evident when a closed-set response format was employed.

Adult↗
PubMed1995

Missed injuries: a case of trauma hide and seek.

The incidence of missed injuries in the trauma population has been reported as low as 2% and as high as 50%. Missed injuries can lead to serious complications and even death. A variety of factors lead to missed injuries: instability of the patient's condition, alterations in the patient's level of consciousness, health care provider inexperience, radiologic errors, technical errors, and admission to an inappropriate physician service. The most common type of missed injuries are musculoskeletal injuries, although missed injury occurs with head, chest, abdominal, spinal, and neurovascular trauma. Strategies such as repeat physical examinations, implementation of protocols for trauma management, and organization of a forum for discussion of errors are methods to decrease missed injuries.

Diagnostic Errors↗
PubMed1994

Circulatory response of young adult trauma victims with alcohol intoxication.

Young adults are a subgroup particularly susceptible to traumatic injury; alcohol intoxication is a major risk factor for trauma in young adults. During the first hours following multiple trauma, however, little is known about the specific effects of alcohol intoxication on the circulatory response of critically injured young adults. The purpose of this prospective study was to compare the circulatory response of 5 severely injured young adults (15-40 years old) with acute alcohol intoxication to the circulatory response of 5 severely injured, nonintoxicated young adults. Data were collected every hour for the first 8 hours after admission to a surgical intensive care unit. Subjects with alcohol intoxication had significantly higher heart rates (t = 2.8176, p < .05) than their nonintoxicated counterparts. Heart rate and blood pressure, however, showed no statistically significant (p < .05) Group x Time interaction between the two groups. Subjects with alcohol intoxication also had injuries that caused more blood loss, more invasive monitoring, more operative procedures, more fluid replacement, and higher oxygen requirements.

Adolescent↗
PubMed1994

Stimulus variability and spoken word recognition. I. Effects of variability in speaking rate and overall amplitude.

The present experiments investigated how several different sources of stimulus variability within speech signals affect spoken-word recognition. The effects of varying talker characteristics, speaking rate, and overall amplitude on identification performance were assessed by comparing spoken-word recognition scores for contexts with and without variability along a specified stimulus dimension. Identification scores for word lists produced by single talkers were significantly better than for the identical items produced in multiple-talker contexts. Similarly, recognition scores for words produced at a single speaking rate were significantly better than for the corresponding mixed-rate condition. Simultaneous variations in both speaking rate and talker characteristics produced greater reductions in perceptual identification scores than variability along either dimension alone. In contrast, variability in the overall amplitude of test items over a 30-dB range did not significantly alter spoken-word recognition scores. The results provide evidence for one or more resource-demanding normalization processes which function to maintain perceptual constancy by compensating for acoustic-phonetic variability in speech signals that can affect phonetic identification.

Female↗
PubMed1994

The near-death experience following multiple trauma.

The NDE is a fascinating but not uncommon phenomenon that some trauma victims experience during physical crises or periods of apparent clinical death. When critical care trauma nurses are familiar with the characteristics of the experience, they are able to assist trauma victims to understand available information about NDEs. More important, critical care nurses are able to assist victims and their families to understand the meanings of the NDE and how it affects their lives.

Critical Care↗
PubMed1994

Alcohol and trauma: the critical link.

The link between traumatic injury and alcohol consumption is strong. Although statistics vary, from one half to one third of trauma victims admitted to critical care units have an alcohol-related injury. The initial role of the critical care nurse is to identify the presence of alcohol by monitoring the patient's BAC. Once the presence of alcohol is confirmed, its effects impact directly on the plan of care that evolves during the critical illness. Nursing interventions focus on four specific areas affected by alcohol: the ability of alcohol to mask injury, the effects of alcohol on medications, alcohol withdrawal, and rehabilitation from alcoholism. By incorporating these four areas into the plan of care, the critical care nurse assists the patient not only to recover from a traumatic injury but also to deal with a problem drinking pattern.

Alcohol Drinking↗
PubMed1993

Auditory filter shapes in normal-hearing, noise-masked normal, and elderly listeners.

To dissociate the effects of age and hearing impairment on changes in frequency selectivity, auditory filter shapes were measured at 2 kHz in four groups of subjects: (1) normal-hearing young subjects; (2) normal-hearing elderly subjects; (3) elderly hearing-impaired listeners; and (4) young normal-hearing listeners with simulated hearing losses. Filter shapes were derived using a modified version of the notched-noise procedure [Glasberg and Moore, Hear, Res. 47, 103-138 (1990)]. Equivalent rectangular bandwidths (ERBs) of auditory filters were not significantly different in young and elderly subjects with normal 2-kHz hearing. Furthermore, filter widths for young subjects with 20- and 40-dB simulated hearing losses overlapped with those obtained from elderly subjects with corresponding degrees of actual hearing loss. One measure that did show significant differences between actual and simulated hearing losses was the degree of filter asymmetry; auditory filters in hearing-impaired listeners were more asymmetrical than those obtained from noise-masked normal-hearing subjects. The dynamic range of auditory filters, however, was comparable for hearing-impaired and noise-masked listeners. Lastly, post-filter detection efficiency was also similar for young and elderly subjects with equivalent hearing levels. These findings suggest that the reduced frequency selectivity often reported for older listeners can be attributed, primarily, to hearing loss rather than increased age. Implications of the results for speech perception in the elderly and models of hearing impairment are discussed.

Acoustic Stimulation↗