Biomedical subjects

Richard A Roberts

Publications and source records attributed to Richard A Roberts.

12 recordsLinked to original sources

PubMed2006

An adaptive clinical test of temporal resolution.

PURPOSE: It has been recommended that diagnostic and screening test batteries for auditory processing disorder (APD) include a measure of temporal gap detection using broadband noise stimuli. Although psychophysical laboratory procedures exist for the measurement of temporal resolution, none are clinically feasible. This study was designed to obtain preliminary data on a new clinical measure of gap detection, the Adaptive Test of Temporal Resolution (ATTR). METHOD: The ATTR, a currently available clinical test (Random Gap Detection Test), and a standard psychophysical laboratory procedure were used to measure gap detection thresholds (GDTs) from a group of 30 young adults with normal hearing. RESULTS: Mean ATTR GDTs were 2.2 ms, consistent with GDTs measured using the psychophysical laboratory procedure (3.2 ms) and significantly smaller than those measured using the Random Gap Detection Test (7.0 ms). CONCLUSIONS: Because it incorporates standard adaptive psychophysical methodology in a computer application that can be used on any desktop computer but does not depend on specialized hardware for application, the ATTR promises to be a clinically feasible addition to the APD test battery.

Acoustic Stimulation↗

PubMed2006

Differentiation of migrainous positional vertigo (MPV) from horizontal canal benign paroxysmal positional vertigo (HC-BPPV).

This article presents an approach to differentiation of migrainous positional vertigo (MPV) from horizontal canal benign paroxysmal positional vertigo (HC-BPPV). Such an approach is essential because of the difference in intervention between the two disorders in question. Results from evaluation of the case study presented here revealed a persistent ageotropic positional nystagmus consistent with MPV or a cupulolithiasis variant of HC-BPPV. The patient was treated with liberatory maneuvers to remove possible otoconial debris from the horizontal canal in an attempt, in turn, to provide further diagnostic information. There was no change in symptoms following treatment for HC-BPPV. This case was diagnosed subsequently as MPV, and the patient was referred for medical intervention. Treatment has been successful for 22 months. Incorporation of HC-BPPV treatment, therefore, may provide useful information in the differential diagnosis of MPV and the cupulolithiasis variant of HC-BPPV.

Aged↗

PubMed2006

Computerized dynamic visual acuity with volitional head movement in patients with vestibular dysfunction.

OBJECTIVES: Patients with uncompensated vestibular dysfunction frequently report blurred vision during head movement, a symptom termed oscillopsia. One way to measure the functional deficit associated with an impaired vestibulo-ocular reflex is by comparing visual acuity from a baseline condition in which there is no head movement to visual acuity obtained during a dynamic condition with head movement. A previously described test incorporated a treadmill upon which patients walked during assessment of visual acuity. The objective of the current investigation was to evaluate an alternative method of assessing dynamic visual acuity that uses volitional head movement instead of walking on a treadmill. METHODS: Fifteen participants with normal vestibular function and 16 participants with impaired vestibular function were enrolled. All participants performed the visual acuity task under baseline conditions with no movement and also under dynamic conditions that included 1) walking on a treadmill and 2) volitionally moving their head in the vertical plane. RESULTS: No difference in performance was observed between the treadmill task and the volitional head movement task. Participants with impaired vestibular function performed more poorly under the dynamic conditions than did participants with normal vestibular function. CONCLUSIONS: The results suggest that the volitional head movement paradigm may be useful in identification of patients with functional deficits of the vestibulo-ocular reflex.

Adult↗

PubMed2006

Efficacy of a new treatment maneuver for posterior canal benign paroxysmal positional vertigo.

Existing treatment maneuvers for posterior canal benign paroxysmal positional vertigo (PC-BPPV) include the Semont liberatory maneuver (SLM) and canalith repositioning maneuver (CRM). Independent investigations reveal that these maneuvers provide an excellent outcome for most patients. However, certain aspects of these maneuvers, such as hyperextension of the neck for CRM and brisk lateral motion for the SLM, are contraindicated for patients with vertebrobasilar insufficiency, cervical spondylosis, back problems, and so forth. A hybrid approach, the Gans repositioning maneuver (GRM) was developed for use with these patients. The purpose of this project was to assess efficacy of the GRM for treatment of PC-BPPV. Two-hundred seven participants were enrolled in this prospective study. All participants were treated with the GRM. Six different clinicians performed the treatments. Participants returned for follow-up at one-week intervals until it was determined that the PC-BPPV was clear. On average, 1.25 GRM treatments were required to resolve the PC-BPPV. The majority of the participants (80.2%) were cleared with one GRM treatment, and 95.6% were clear after two treatments. Recurrence rate was 5%. There was no difference in outcome based on clinician. The GRM is an efficacious treatment maneuver for PC-BPPV and may be preferential for use in patients with neck, back, hip, and/or mobility issues that contraindicate the use of SLM or CRM.

Adult↗

PubMed2005

Effects of age and hearing loss on gap detection and the precedence effect: narrow-band stimuli.

Deficits in temporal resolution and/or the precedence effect may underlie part of the speech understanding difficulties experienced by older listeners in degraded acoustic environments. In a previous investigation, R. Roberts and J. Lister (2004) identified a positive correlation between measures of temporal resolution and the precedence effect, specifically across-channel gap detection (as measured dichotically) and fusion. Across-channel gap detection may also be measured using frequency-disparate markers. Thus, the present investigation was designed to determine if the relation is specific to dichotic gap detection or may generalize to all types of across-channel gap detection. Gap-detection thresholds (GDTs) for fixed-frequency and frequency-disparate markers and lag-burst thresholds (LBTs) were measured for 3 groups of listeners: young with normal hearing sensitivity (YNH), older with normal hearing sensitivity (ONH), and older with sensorineural hearing loss (OIH). Also included were conditions of diotic and dichotic GDT. Largest GDTs were measured for the frequency-disparate markers, whereas largest LBTs were measured for the fixed-frequency markers. ONH and OIH listeners exhibited larger frequency-disparate and dichotic GDTs than YNH listeners. Listener age and hearing loss appeared to influence temporal resolution for frequency-disparate and dichotic stimuli, which is potentially important for the resolution of timing cues in speech. Age and hearing loss did not significantly influence fusion as measured by LBTs. Within each participant group, most GDTs and LBTs were positively, but not significantly, correlated. For all participants combined, across-channel GDTs and LBTs were positively and significantly correlated. This suggests that the 2 tasks may rely on a common across-channel temporal mechanism.

Acoustic Stimulation↗

PubMed2005

Prevalence of vestibulopathy in benign paroxysmal positional vertigo patients with and without prior otologic history.

The purpose of this study was to determine the prevalence of reduced or absent labyrinthine reactivity (vestibulopathy) in two groups of participants with posterior canal BPPV. One group had prior diagnosis of otologic disease (positive history group). No one in the second group had ever been diagnosed with otologic disease (negative history group). Caloric responses were retrospectively analyzed for the two groups. Patients with a positive history exhibited a greater prevalence of vestibulopathy than patients with a negative history. The positive history group, on average, also exhibited a larger unilateral weakness than those patients in the negative history group. We conclude that patients with BPPV and a history of otologic disease are more likely to present with vestibulopathy, than patients with BPPV and no history of otologic disease. This finding supports the benefit of complete vestibular evaluation in patients with BPPV to ensure comprehensive and successful treatment outcome.

Adult↗

PubMed2005

Treatment of benign paroxysmal positional vertigo: necessity of postmaneuver patient restrictions.

Benign paroxysmal positional vertigo (BPPV) is the most common cause of vertigo, resulting from migration of otoconia into the semicircular canals. Several treatment methods involving positioning maneuvers that return the otoconia to the utricle have been described. Following treatment, most patients are provided with a variety of activity restrictions. Previous studies suggest that, overall, BPPV treatment may be successful without these restrictions. The purpose of this study was to determine the necessity of postmaneuver restrictions using an experimental and control group with participants matched for age, gender, involved ear, and symptoms. A canalith repositioning maneuver was used to treat the BPPV. During postmaneuver instruction, the 21 participants assigned to the restricted group were provided with typical activity restrictions. Twenty-one participants assigned to the nonrestricted group were given no postmaneuver restrictions. Only one participant in the restricted group and two participants in the nonrestricted group were not clear at the one-week follow-up appointment. Results indicated that postmaneuver restrictions do not improve treatment efficacy.

Adult↗

PubMed2004

Effects of reverberation on fusion of lead and lag noise burst stimuli.

The purpose of this investigation was to determine the effects of reverberation on the precedence effect by obtaining thresholds for perception of leading and lagging noise burst stimuli as separate auditory events. In Experiment 1, lag burst thresholds for 4-ms noise bursts were measured in a simulated reverberant and anechoic environment for nine subjects with normal hearing at presentation levels of 10, 20, and 30 dB SL. Results indicated that lag burst thresholds obtained in the reverberant environment were higher than those obtained in the anechoic environment, with no effect of sensation level. In Experiment 2, three new stimulus conditions, two monaural and one binaural control, were employed. For one monaural condition, the stimuli were equal in level and for the other, the leading stimulus was more intense than the lagging stimulus. For the binaural control condition, the stimuli were presented from a perceived spatial location of 0 degrees azimuth. In the monaural and binaural control conditions, lag burst thresholds were lower than those obtained in the reverberant environment of Experiment 1. There was no difference between lag burst thresholds obtained in either environment for the monaural and binaural control conditions compared to the anechoic condition of Experiment 1. Results of Experiment 2 indicate that the higher lag burst thresholds observed in Experiment 1 are not fully explained by a peripheral masking effect.

Acoustic Stimulation↗

PubMed2004

Effects of age and hearing loss on gap detection and the precedence effect: broadband stimuli.

Older listeners with normal-hearing sensitivity and impaired-hearing sensitivity often demonstrate poorer-than-normal performance on tasks of speech understanding in noise and reverberation. Deficits in temporal resolution and in the precedence effect may underlie this difficulty. Temporal resolution is often studied by means of a gap-detection paradigm. This task is similar to binaural fusion paradigms used to measure the precedence effect. The purpose of this investigation was to determine if within-channel (measured with monotic and diotic gap detection) or across-channel (measured with dichotic gap detection) temporal resolution is related to fusion (measured with lag-burst thresholds; LBTs) under dichotic, anechoic, and reverberant conditions. Gap-detection thresholds (GDTs) and LBTs were measured by means of noise-burst stimuli for 3 groups of listeners: young adults with normal-hearing sensitivity (YNH), older adults with normal-hearing sensitivity (ONH), and older adults with impaired-hearing sensitivity (OIH). The GDTs indicated that across-channel temporal resolution is poorer than within-channel temporal resolution and that the effects of age and hearing loss are dependent on condition. Results for the fusion task indicated higher LBTs in reverberation than for the dichotic and anechoic conditions, regardless of group, and no effect of age or hearing loss for the nonreverberant conditions. However, higher LBTs were observed in the reverberant condition for the ONH listeners. Further, there was a correlation between across-channel temporal resolution and fusion in reverberation. Gap detection and fusion may not necessarily reflect the same underlying processes; however, across-channel gap detection may influence fusion under certain conditions (i.e., in reverberation).

Acoustic Stimulation↗

PubMed2003

Effects of noise and reverberation on the precedence effect in listeners with normal hearing and impaired hearing.

The purpose of this study was to determine the effects of reverberation and noise on the precedence effect in listeners with hearing loss. Lag burst thresholds (LBTs) for 4-ms noise bursts were obtained for 2 groups of participants: impaired hearing and normal hearing. Data were collected in reverberant and anechoic environments in quiet and noise, at sensation levels of 10, 20, 30, 40, and 50 dB. Results indicated a significant effect of reverberation on LBTs for both participant groups. LBTs increased with sensation level in the reverberant environment and decreased with increasing sensation level in the anechoic environment. There was no effect of hearing loss on LBTs. When the change in LBT due to noise was compared, the effect of noise depended on group and environment, with a greater effect of noise on the performance of listeners with impaired hearing. It is likely that the ability to fuse direct sounds and early reflections is degraded in listeners with impaired hearing and that this contributes to the difficulties experienced by these listeners in reverberation and noise.

Adult↗

PubMed2003

Speech perception benefits from sound field FM amplification.

The effects of sound field FM amplification (SFA) on speech perception performance were investigated in this 2-year study. Kindergarten children with normal hearing were randomly assigned to a treatment group, which comprised 7 classrooms that had SFA systems installed in them, and to a control group, which comprised another 7 classrooms that did not have any amplification available. The children were followed from the beginning of kindergarten through the end of first grade. Improvements in speech perception performance were measured for both groups, with the treatment group demonstrating progress much sooner than the control group. However, this difference was not apparent by the end of the study. The only significant difference measured between the treatment and control groups was that the treatment group performed significantly better than the control group when the stimuli were presented with SFA for the treatment group and without SFA for the control group. The teachers who used SFA enjoyed using amplification in their classrooms and felt that their students enjoyed using it as well.

Acoustics↗

PubMed2002

Effects of hearing loss on echo thresholds.

OBJECTIVE: The purpose of this investigation was to determine the effects of hearing loss on the perception of echoes. DESIGN: Echo thresholds were measured for eight listeners with normal hearing and nine listeners with impaired hearing. Pairs of 4-msec noise bursts were presented to each listener with onset-to-onset delays ranging from 2 to 16 msec. Echo thresholds were obtained at signal presentation levels of 10, 20, 30, 40, and 50 dB SL. RESULTS: Results revealed differences between the psychometric functions of the two subject groups. Psychometric functions of the subjects with impaired hearing indicated higher echo thresholds than for the subjects with normal hearing. In addition, echo thresholds at 10 dB SL were significantly higher than echo thresholds measured at 40 dB SL for both subject groups. CONCLUSION: Listeners with impaired hearing exhibit higher echo thresholds than listeners with normal hearing. The higher echo thresholds for listeners with impaired hearing may account, at least in part, for difficulty on tasks such as localization in everyday listening environments.

Audiometry, Pure-Tone↗