Biomedical subjects

Kathy R Vander Werff

Publications and source records attributed to Kathy R Vander Werff.

3 recordsLinked to original sources

PubMed2005

Effect of audiometric configuration on threshold and suprathreshold auditory steady-state responses.

OBJECTIVE: The purpose of this study was to examine the correlation between auditory steady-state response (ASSR) thresholds and behavioral thresholds in hearing-impaired adults with two common audiometric configurations. A second goal was to compare suprathreshold ASSR growth functions in these two subject groups and to determine whether these growth functions could be used clinically to improve threshold estimation. DESIGN: Thirty adults participated, including 10 subjects with normal hearing, 10 subjects with flat moderately severe sensorineural hearing loss, and 10 subjects with sloping high-frequency sensorineural hearing loss. The accuracy of ASSR threshold estimations for the frequencies of 500, 1000, 2000, and 4000 Hz was compared across groups. In addition, ASSRs were recorded at multiple suprathreshold intensity levels, and the growth of the response was compared across subject groups. RESULTS: ASSR and behavioral thresholds were strongly correlated across all subjects, with no significant difference by audiometric configuration. Slightly poorer correlations were obtained in the normal-hearing subjects than in hearing-impaired subjects and for the 500-Hz test frequency compared with the higher stimulus frequencies. Subtraction and regression methods for predicting behavioral thresholds from ASSR thresholds were equally accurate. Suprathreshold amplitude growth was variable among individuals, but mean growth functions showed steeper slopes in hearing-impaired subjects than in normal-hearing subjects, particularly for the higher frequencies (2000 to 4000 Hz). However, there was not a significant difference in the slopes of amplitude growth functions between subjects with sloping versus flat audiometric configurations for these frequencies, and estimation of threshold from suprathreshold ASSR amplitude growth functions was not advantageous. CONCLUSIONS: ASSR thresholds accurately predicted behavioral threshold equally well for flat or sloping audiometric configurations. The accuracy of threshold estimation for either audiometric configuration and the similar growth function slopes may suggest that there is little spread of activation to neighboring regions of the cochlea when using multiple 100% AM stimuli in subjects with moderately sloping losses. The small amplitude of the ASSR response and individual variability may make threshold estimation based on extrapolation from suprathreshold ASSR responses impractical.

Acoustic Stimulation↗

PubMed2004

Estimating air-bone gaps using auditory steady-state responses.

Auditory steady-state responses (ASSR) were recorded using stimuli presented both via air conduction (AC ASSR) and bone conduction (BC ASSR) in 10 normal-hearing subjects with different degrees of simulated conductive hearing losses. The ASSR-estimated ABG (air-bone gap) was compared with the ABG measured using traditional pure-tone audiometric procedures. Reproducibility of the BC ASSR electrophysiological thresholds was also assessed. Additionally, a group of five subjects with profound sensorineural hearing loss was used to establish stimulation levels in which the BC ASSR was contaminated by stimulus artifact. Results of this investigation showed that the ASSR and behavioral ABGs were strongly correlated with each other (r = .81). However, ASSR-estimated ABGs slightly overestimated the magnitude of the behavioral. Reproducibility of the BC ASSR electrophysiological thresholds was good. Data from the five subjects with profound hearing loss, however, demonstrated that the levels where stimulus artifact became problematic were relatively low. This means BC stimulation may be appropriate only for subjects with normal or mildly impaired cochlear sensitivity.

Adult↗

PubMed2002

Comparison of auditory steady-state response and auditory brainstem response thresholds in children.

Recently, auditory steady-state responses (ASSRs) have been proposed as an alternative to the auditory brainstem response (ABR) for threshold estimation. The goal of this study was to investigate the degree to which ASSR thresholds correlate with ABR thresholds for a group of sedated children with a range of hearing losses. Thirty-two children from the University of Iowa Hospitals and Clinics ranging in age from 2 months to 3 years and presenting with a range of ABR thresholds participated. Strong correlations were found between the 2000-Hz ASSR thresholds and click ABR thresholds (r = .96), the average of the 2000- and 4000-Hz ASSR thresholds and click ABR thresholds (r = .97), and the 500-Hz ASSR and 500-Hz toneburst ABR thresholds (r = .86). Additionally, it was possible to measure ASSR thresholds for several children with hearing loss that was great enough to result in no ABR at the limits of the equipment. The results of this study indicate that the ASSR may provide a reasonable alternative to the ABR for estimating audiometric thresholds in very young children.

Auditory Perception↗