Biomedical subjects

Brent Spehar

Publications and source records attributed to Brent Spehar.

3 recordsLinked to original sources

PubMed2005

Auditory-visual speech perception and auditory-visual enhancement in normal-hearing younger and older adults.

OBJECTIVE: The purpose of the present study was to examine the effects of age on the ability to benefit from combining auditory and visual speech information, relative to listening or speechreading alone. In addition, the study was designed to compare visual enhancement (VE) and auditory enhancement (AE) for consonants, words, and sentences in older and younger adults. DESIGN: Forty-four older adults and 38 younger adults with clinically normal thresholds for frequencies of 4 kHz and below were asked to identify vowel-consonant-vowels (VCVs), words in a carrier phrase, and semantically meaningful sentences in auditory-only (A), visual-only (V), and auditory-visual (AV) conditions. All stimuli were presented in a background of 20-talker babble, and signal-to-babble ratios were set individually for each participant and each stimulus type to produce approximately 50% correct in the A condition. RESULTS: For all three types of stimuli, older and younger adults obtained similar scores for the A condition, indicating that the procedure for individually adjusting signal-to-babble ratios was successful at equating A scores for the two age groups. Older adults, however, had significantly poorer performance than younger adults in the AV and V modalities. Analyses of both AE and VE indicated no age differences in the ability to benefit from combining auditory and visual speech signals after controlling for age differences in the V condition. Correlations between scores for the three types of stimuli (consonants, words, and sentences) indicated moderate correlations in the V condition but small correlations for AV, AE, and VE. CONCLUSIONS: Overall, the findings suggest that the poorer performance of older adults in the AV condition was a result of reduced speechreading abilities rather than a consequence of impaired integration capacities. The pattern of correlations across the three stimulus types indicates some overlap in the mechanisms mediating AV perception of words and sentences and that these mechanisms are largely independent from those used for AV perception of consonants.

Acoustic Stimulation↗

PubMed2004

Time-compressed visual speech and age: a first report.

OBJECTIVE: The purpose of this research was to investigate the effects of age on the ability to identify temporally altered visual speech signals. DESIGN: Two groups of adult lipreaders, older (N = 20) and younger (N = 15), were tested on perception of visual-only speech signals. Identification performance was measured for time-compressed, time-expanded, and unaltered versions of words with visual only speech. RESULTS: An overall reduction in lipreading ability was observed as a function of age. However, in contrast to results with time-altered auditory speech, older adults did not show a disproportionate change to speeded or slowed visual speech. CONCLUSIONS: The absence of age effects in the identification of temporally altered visual speech signals stands in contrast to the considerable evidence that older adults are disproportionately affected by temporal alterations of auditory speech signals. These results argue against a generalized slowing of information processing in older adults and instead point to modality specific changes in temporal processing abilities.

Adult↗

PubMed2003

19th-century camouflaged mechanical hearing devices.

HYPOTHESIS: The aim of this review is to present 19th century mechanical hearing devices that were designed for concealment or camouflage. BACKGROUND: Extensive literature, past and current, along with museum catalogs, trade catalogs, and advertisements, were examined to identify mechanical devices designed for concealment. METHODS: Several mechanical devices were selected for acoustic gain measurements. Measurements were made in an anechoic chamber using a Knowles Electronics Manikin for Acoustic Research fitted with a Zwislocki coupler and a pressure microphone in the right ear. One-third-octave bands of noise were presented via a KLH Model 6 loudspeaker placed at a distance of 2.23 m on-axis. The sound level at the ear of the Knowles Electronics Manikin for Acoustic Research was recorded with and without the device in place. RESULTS: A wide variety of 19th century hearing devices designed for concealment were identified. Some hearing devices, such as fans, parasols, lorgnettes, water canteens, walking sticks, chairs/thrones, hats, and books, were concealed within everyday items. Other hearing devices, such as artificial conchae, bouquet holders, and hair and beard receptors, wereconcealed on the person. The insertion gain of a representative concealed device, the Aurolese Phone, averaged approximately 3.5 dB in the range of frequencies most relevant for speech communication. CONCLUSIONS: The ingenuity behind the design of 19th century mechanical hearing devices created for concealment or camouflage is to be commended. For the Aurolese Phone, some acoustic benefit was possible despite design constraints imposed by its concealed nature.

England↗