Biomedical subjects

C W Turner

Publications and source records attributed to C W Turner.

At least 37 records · Page 2Linked to original sources

PubMed1997

The time course of hearing aid benefit.

OBJECTIVE: The present study sought to determine whether benefit derived from hearing aid use increases with hearing aid experience. This question is of considerable interest to both researchers and clinicians. Several previous investigations recently published have obtained mixed results. DESIGN: Control conditions were provided to address the potential influences of practice effects and changes in preferred hearing aid gain. The experimental group consisted of 13 hearing-impaired listeners about to be fit with their first hearing-aid. The control group consisted of 13 hearing aid users with at least 1 yr's experience with their hearing aids. The control group permitted examination of practice effects that may have confounded previous results showing increases in benefit with experience. Hearing aid benefit was defined as aided speech recognition ability minus unaided speech recognition ability and was assessed repeatedly over 18 wk. Two measures of hearing aid benefit were employed: an objective syllable recognition task and a subjective questionnaire. For the objective measure, hearing aid benefit was assessed for the condition of fixed hearing aid gain and also for the condition of subject-adjusted hearing aid gain to examine effects of changes in audibility that may have influenced benefit and confounded previous results. RESULTS: The objective measure of group mean hearing aid benefit increased significantly over time for both gain conditions for the new hearing aid users, but did not increase for the long-standing control group. Subjective benefit increased over time, but without statistical significance for the new hearing aid users, and was essentially unchanged for the long-standing control group. CONCLUSIONS: Results suggest that the observed improvements in speech recognition are not due to increases in audibility nor to simple practice effects. The overall improvements in benefit over time were of statistical significance and also practical importance for studies of group differences. However, the improvements are too small to be observed consistently for individual hearing aid users.

Aged↗

PubMed1997

Formant transition duration and speech recognition in normal and hearing-impaired listeners.

Listeners with sensorineural hearing loss often have difficulty discriminating stop consonants even when the speech signals are presented at high levels. One possible explanation for this deficit is that hearing-impaired listeners cannot use the information contained in the rapid formant transitions as well as normal-hearing listeners. If this is the case, then perhaps slowing the rate of frequency change in formant transitions might assist their ability to perceive these speech sounds. In the present study, sets of consonant plus vowel (CV) syllables were synthesized corresponding to /ba, da, ga/ with formant transitions for each set ranging from 5 to 160 ms in duration. The listener's task was to identify the consonant in a three-alternative, closed-set response task. The results for normal-hearing listeners showed nearly perfect performance for transitions of 20 ms and longer, whereas the shortest transitions yielded poorer performance. A group of eight hearing-impaired listeners pure-tone averages (PTAs) ranging from 30 to 62 dB HL) was also tested. The hearing-impaired listeners tended to show poorer performance than the normals for transitions of all durations; however, the performance of a few hearing-impaired subjects was equal to that of normals for the shortest-duration transitions. A strong inverse relation was observed between degree of hearing loss and improvement in score as a function of transition duration. These results suggest that increasing the duration of formant transitions for listeners with more severe hearing losses may not provide a helpful solution to their speech recognition difficulties.

Hearing↗

PubMed1997

Validity of utilization management criteria for psychiatry.

OBJECTIVE: This study examined the validity of four psychiatric utilization management criteria sets: the 1992 and 1993 InterQual Intensity, Severity, and Discharge (ISD) criteria, the Managed Care Appropriateness Protocol, and an instrument developed by the Department of Veterans Affairs (VA). METHOD: The appropriateness of acute care admission and continued stay for 70 randomly selected VA psychiatric inpatients was retrospectively assessed with each criteria set. The sensitivity and specificity of each instrument were evaluated by comparing its assessments to the consensus of judgments of a panel of expert psychiatrists who reviewed the same cases. Sensitivity was defined as the proportion of admissions or continued-stay days the panel found appropriate for acute care that the criteria judged to be appropriate for acute care; specificity was the proportion the panel found inappropriate for acute care that the criteria judged to be inappropriate for acute care. RESULTS: For admissions, there were only minor differences in the validity of the four criteria sets as assessed by agreement with the panel's judgments. For each of 4 continued-stay days studied, either the sensitivity or specificity of the 1993 InterQual ISD criteria was below 0.30. The specificity of the 1992 InterQual ISD criteria was below 0.60 for 2 days. In contrast, for the Managed Care Appropriateness Protocol, sensitivity was 0.73-0.93 and specificity was 0.78-0.88 over the 4 days. CONCLUSIONS: The findings raise major concerns about the validity of the widely used InterQual ISD psychiatry criteria, suggest that the Managed Care Appropriateness Protocol may be a useful tool for psychiatric utilization management, strongly underline the need to validate all criteria used to assess medical care, and support the appropriateness of the procedures used to perform these assessments.

Adult↗

PubMed1997

Use of Iliad to improve diagnostic performance of nurse practitioner students.

Nurse practitioners (NPs) have dual goals as primary care providers, combining the traditional goals of nursing with extended goals as diagnosticians. Diagnostic reasoning, therefore, is a critical component of NP education. Iliad, a computerized diagnostic reasoning expert system, has been used effectively to teach diagnostic skills to medical students. A pilot study was undertaken to determine the effects of Iliad training on NP students' diagnostic skill performance and to identify technical and instructional issues of implementation. The study found that the use of Iliad improved NP students' diagnostic reasoning, and that the training effects were modified by prior nursing experience. Successful use of Iliad required planning, faculty commitment, and technical support.

Clinical Competence↗

PubMed1996

Engraftment potential of different sources of human hematopoietic progenitor cells in BNX Mice.

Human hematopoietic progenitor cells (HPCs) from mobilized peripheral blood mononuclear cells (PBMCs), adult bone marrow (ABM), and fetal bone marrow (FBM) were evaluated for their ability to produce multilineage human hematopoietic engraftment in vivo. Sublethally irradiated BNX (beige/nude/xid) mice were injected with either unfractionated cells or CD34+ cells purified from these sources. The presence of human cells in the mouse PB, BM, and spleen was evaluated by flow cytometry at either 6 to 8 weeks or 6 months postinjection. Recipients with > or = 1% human cells in any of these tissues were considered chimeric. Of 26 mice injected with FBM, 4 showed up to 73% human cells in the BM or spleen at 6 months. The phenotypes of these cells included CD13/33+ myelomonocytic cells (38%), CD19+ B cells (67%), and CD34+ progenitor cells (28%). In contrast, ABM gave rise to a mean of 5% human cells in the PB in 2 of 42 (4%) recipients at 6 to 8 weeks. These circulating human cells were predominantly CD3+, whereas CD13/33+ and CD34+ cells were detected in the BM for up to 6 months. A total of 18% of mice injected with PBMCs showed a mean of 36% human cells in the PB. Both the BM and spleens of PBMC-injected mice contained CD3+ cells in a proportion similar to that observed in the PB. These CD3+ cells were phenotypically mature CD4+,CD8- or CD4-,CD8+ T cells and coexpressed a variety of Vbeta T-cell receptor (TCR) genes. The percentage of CD3+ cells in the circulation of chimeric recipients injected with either FBM, ABM, or PBMCs correlated well with the input CD3+ cell dose for each of these HPC sources (r = .99). The high levels of engraftment of CD3+ cells in recipients of PBMCs and the long-term multilineage engraftment of FBM recipients have important implications for developing strategies to study the regulation of these human cells in vivo.

Adult↗

PubMed1996

A meta-analytic review of research on hostility and physical health.

A new meta-analysis of research on hostility and physical health was conducted that includes 15 studies used in previous meta-analytic reviews and 30 new independent studies. Overall, the results suggest that hostility is an independent risk factor for coronary heart disease (CHD). For structured interview indicators of potential for hostility, the weighted mean r was .18. After controlling for other risk factors for CHD, the widely used Cook-Medley Hostility Scale and other cognitive-experiential measures were most predictive of all-cause mortality (weighted mean r = .16) and, to a lesser extent, CHD (weighted mean r = .08). Similar to other areas of research, the increased use of high-risk studies in recent years produced an increase in null findings.

Anger↗

PubMed1996

Effect of single-channel compression on temporal speech information.

Although syllabic compression systems are available in many currently marketed hearing aids, the benefit of such systems continues to be debated. The goal of this study was to determine the effect of single-channel amplitude compression on use of speech information were considered, with particular focus on temporal cues. Speech recognition scores were assessed under four conditions, using two types of speech materials. Both temporal and spectral information were provided in the FullSpeech or natural speech stimuli. Unlike previous studies in which use of temporal information may have been confounded by spectral changes, in this study the listener's ability to use temporal information was tested directly using signal-correlated noise (SCN) stimuli, which consisted of a time-varying speech envelope modulating a broad-band noise carrier. Two conditions (FullSpeech and SCN) retained their natural amplitude characteristics. In two corresponding conditions the same stimuli were compressed digitally, using compression parameters appropriate for syllabic compression. This compression reduced the range of time-intensity variations. Recognition scores were obtained from listeners with mild-to-severe sensorineural loss and from a control group of listeners with normal hearing. All stimuli were presented at high levels to reduce potential effects of reduced audibility. Additionally, short-term speech level measurements were compared to individual listener's hearing thresholds to determine the range of speech levels in each frequency region that was audible for each stimulus condition. Results demonstrated no effect of compression on recognition scores for either the FullSpeech or SCN signals for listeners with normal hearing or listeners with hearing loss. This suggests that single-channel syllabic compression processing, of the type used in this study, does not alter the temporal (or spectral) signal sufficiently to cause decreased recognition for VCV syllables when speech audibility is maintained.

Adult↗

PubMed1996

A review of past research on changes in hearing aid benefit over time.

Hearing aid benefit refers to a relative change in performance on a particular measure between aided and unaided listening conditions. A number of studies in recent years have investigated the hypothesis that hearing aid benefit increases over time after the initial fitting of the aid. Both objective (speech recognition) and subjective (questionnaire) measures have been used to measure hearing aid benefit. Some studies have reported a positive increase over time in group mean benefit, and some have reported no change in benefit, whereas none have reported a group mean negative change in benefit. However, individual subjects in these studies can show changes in benefit in either a positive or negative direction. The variability across subjects in each study has been large in comparison with the observed amount of benefit increase. In this review of the literature, it is argued that the studies present essentially similar results and the range of values across subjects in the various studies shows considerable overlap. Although there does appear to be a tendency for hearing aid benefit to increase over time, there are other, much stronger, factors influencing changes in hearing aid benefit that make it impossible at present to predict which patients will show a reliable increase (or decrease) in hearing aid benefit over time.

Deafness↗

PubMed1996

Report of the Eriksholm Workshop on auditory deprivation and acclimatization.

The terminology used in studies documenting changes in auditory performance following fitting of hearing aids has been diverse. Definitions for the auditory deprivation effect and auditory acclimatization are offered as a first step in rationalization. Two statements summarize current knowledge concerning auditory deprivation effects and auditory acclimatization, as well as considering the potential implications for research, field trial and clinical practice applications. Potential areas for future research are identified.

Auditory Perception↗

PubMed1996

Use of a correlational method to estimate a listener's weighting function for speech.

The purpose of this study was to determine if it is feasible to use the correlational method (Lutfi, 1995; Richards and Zhu, 1994) to estimate how listeners use or weight the information contained within various frequency bands of speech. Three naturally spoken vowel-consonant-vowel (VCV) syllables (/aba/, /aga/, and /ada/) were presented monaurally to listeners. Each of the VCV waveforms were filtered into three separate frequency bands (i.e., low, mid, and high). Each band was then independently and randomly degraded at various signal-to-noise (S/N) levels (-7, -5, -3, -1, or +1). On each trial, listeners were asked to identify the VCV that was presented to them. For each trial, the S/N level of each frequency band, the stimulus that was presented, and the listener's responses were all recorded and stored in a file. From this trial-by-trial data, a point biserial correlation was computed between the listener's response (correct or incorrect identification) and the degradation within each frequency band. The stronger the correlation, the greater influence that given frequency band had on the listener's performance on the task. From these relations it was shown that it is possible to obtain a listener's weighting function for speech. Results showed that although most listeners weighted the mid-frequency band the greatest, several of the listeners used different weighting strategies to perform the task. Several methodological issues are discussed in regard to improving the future application of the correlational method to speech.

Humans↗

PubMed1996

Effectiveness of a family skills training program for substance use prevention with inner city African-American families.

The effectiveness of the Safe Haven Program for the prevention of substance use, a family skills training program for African-American families, was evaluated through a nonequivalent comparison, repeated measures, quasi-experimental design which included pre- and posttest parent and child interviews, including the Moos Family Environment Scale and the Achenbock and Edelbrock Child Behavior Checklist. The results indicate that the Safe Haven Program is effective in increasing parenting efficacy and behaviors toward children, improving the childrens' risk and protective factors and behaviors, and supporting treatment reductions in the parent and family illegal substance use.

Adolescent↗

PubMed1995

Gender effects of romantic themes in erotica.

The hypothesis that women would be more aroused to explicit erotica containing a romantic (rather than nonromantic) theme while men would not be affected by the thematic manipulation was tested, 164 college students (91 male and 73 female), 21 years of age and older, viewed one of four video vignettes taken from commercially available sexually explicit video tapes. The four videos represented the systematic manipulation of two independent variables: (i) high vs. low expression of love and affection (e.g, kissing, nongenital touching, and verbal expressions of caring); and (ii) high vs. moderate sexual explicitness (i.e., "hard" vs. "soft" X-rated material). The results indicated that both male and female subjects rated the high explicit/high romantic vignette as significantly more arousing than the high explicit/low romantic vignette. Thus, the finding for males was contrary to expectations. The results are, however, consistent with the recent movement to romanticize highly explicit sexual material. Theoretical implications of these findings are examined.

Adult↗

PubMed1995

Use of temporal envelope cues in speech recognition by normal and hearing-impaired listeners.

The temporal acuity of listeners with sensorineural hearing loss is currently a matter of some controversy. In this study, the ability of normal-hearing and hearing-impaired listeners to utilize temporal cues of speech was measured directly. In addition to natural (unprocessed) nonsense syllables, several processed-speech conditions were employed. Nonsense syllables were digitally processed to remove the original spectral information, resulting in a time-varying speech envelope amplitude modulating a noise carrier. The processed-speech conditions were the envelope of a broadband speech signal modulating a broadband noise, a low-pass speech signal modulating a low-pass noise, a high-pass speech signal modulating a high-pass noise, and a two-channel signal comprised of the low- and high-pass modulated signals combined. Recognition of the envelope stimuli in quiet and also in modulated and steady noise backgrounds was tested. Listeners were tested at presentation levels yielding their maximum performance on a syllable recognition task. The hearing-impaired listeners performed more poorly on a recognition task than the normal-hearing listeners for unprocessed speech signals. However, for listeners with hearing losses of either flat or sloping configuration, there was no significant deficit in their ability to use temporal cues in speech, even in frequency regions of hearing loss up to 70 dB HL. These results demonstrate that moderate to severe sensorineural hearing loss does not impair the temporal (nonspectral) acuity of listeners in terms of speech recognition, when audibility of the stimuli is compensated for.

Hearing↗

PubMed1995

Assessing the behavioral impact of a diagnostic decision support system.

This paper describes a prototype for research to evaluate the impact of diagnostic decision support systems on the behavior of physicians. Several indices that can be used to quantify the magnitude of impact are proposed. A large medical diagnostic knowledge base in internal medicine (the Iliad knowledge base) was used in this evaluation. The impact on behavior when different inference models are run against this knowledge base is evaluated for two different case domains and physician's specialties.

Analysis of Variance↗

PubMed1994

Patient adherence and adjustment in renal dialysis: a person x treatment interactive approach.

We classified 52 in-center hemodialysis patients and 34 self-treated, continuous ambulatory peritoneal dialysis (CAPD) patients on two latent variable indices reflecting patient coping style (i.e., "Information Vigilance" and "Active Coping"). The concurrent and prospective interactive effects of Dialysis Type and Coping Style were examined on patient dietary and medication adherence and on patient depression. In cross-sectional analyses, higher Information Vigilance was associated with better dietary adherence for CAPD patients but poorer adherence for In-Center Hemodialysis patients. No significant effects were found on a measure of medication adherence. Information Vigilance exerted a concurrent main effect on depression, such that higher scores were associated with less depression irrespective of dialysis type. Higher Active Coping scores were associated with lower residualized change in depression for both types of dialysis.

Adaptation, Psychological↗

PubMed1994

Predictors of survival among hemodialysis patients: effect of perceived family support.

The authors examined the role of perceived family support and symptoms of depression as predictors of survival in a sample of 78 in-center hemodialysis patients. Cox regression analysis revealed significant effects for family support (p < .005), blood urea nitrogen (p < .01), and age (p < .005). The effect for depression was not significant. The Cox model indicated that a 1-point increase on the family support measure was associated with a 13% reduction in the hazard rate (i.e., mortality). Estimated 5-year mortality rates among low family support patients were approximately 3 times higher than estimated mortality for high support patients. Differences in patient adherence to the dietary and medication regimens failed to explain the significant effect of family support.

Age Factors↗

PubMed1994

Masking of speech in young and elderly listeners with hearing loss.

This study examined the contributions of various properties of background noise to the speech recognition difficulties experienced by young and elderly listeners with hearing loss. Three groups of subjects participated: young listeners with normal hearing, young listeners with sensorineural hearing loss, and elderly listeners with sensorineural hearing loss. Sensitivity thresholds up to 4000 Hz of the young and elderly groups of listeners with hearing loss were closely matched, and a high-pass masking noise was added to minimize the contributions of high-frequency (above 4000 Hz) thresholds, which were not closely matched. Speech recognition scores for monosyllables were obtained in the high-pass noise alone and in three noise backgrounds. The latter consisted of high-pass noise plus one of three maskers: speech-spectrum noise, speech-spectrum noise temporally modulated by the envelope of multi-talker babble, and multi-talker babble. For all conditions, the groups with hearing impairment consistently scored lower than the group with normal hearing. Although there was a trend toward poorer speech-recognition scores as the masker condition more closely resembled the speech babble, the effect of masker condition was not statistically significant. There was no interaction between group and condition, implying that listeners with normal hearing and listeners with hearing loss are affected similarly by the type of background noise when the long-term spectrum of the masker is held constant. A significant effect of age was not observed. In addition, masked thresholds for pure tones in the presence of the speech-spectrum masker were not different for the young and elderly listeners with hearing loss.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1994

Forward- and backward-masked intensity discrimination measured using forced-choice and adjustment procedures.

A "midlevel" hump in the intensity jnd has been reported for pure tones preceded [e.g., Zeng et al., Hear. Res. 55, 223-230 (1991)] or followed [Plack and Viemeister, J. Acoust. Soc. Am. 92, 3097-3101 (1992)] by an intense masker where the signal-masker interval was 100 ms. These previous studies used forced-choice procedures, in which subjects were required to indicate the more intense tone. Plack and Viemeister [J. Acoust. Soc. Am. 92, 3097-3101 (1992)] have proposed that the task of judging the intensity of the short probe tone, when it is presented along with an intense masker, may lead to cognitive or central factors influencing the results. The present experiments attempted to reduce these possible effects by measuring intensity jnd's using two additional paradigms. First, a "multiple-look" forced-choice method, in which subjects listened to the stimulus pairs several times before responding, was used to obtain only forward-masked intensity jnd's. Second, the method of adjustment was used to obtain both forward- and backward-masked intensity jnd's. Both the standard forced-choice method and the multiple-look forced-choice method yielded jnd data with a midlevel hump, when compared to jnd's measured without a masker. In contrast, jnd's obtained with the method of adjustment yielded jnd data with no midlevel hump. The present results suggest that the traditional method of adjustment for intensity discrimination, where subjects adjust the signal level to a point of subjective equality, may measure a fundamentally different quantity than that measured by forced-choice procedures.

Humans↗