Congruent and incongruent semantic context influence vowel recognition.

The influence of sentence context on the recognition of naturally spoken vowels degraded by reverberation and Gaussian noise was investigated. Target words were paired to have similar consonant sounds but different vowels (e.g., map/mop) and were embedded early in sentences which provided three types of semantic context. Fifty-eight normal-hearing, young adults were presented with sentences in which acoustic and semantic cues agreed either weakly (neutral) or strongly (congruent) or the cues strongly disagreed (incongruent). One vowel pair (/epsilon/-/ae/) was selected to be easier to recognize than the other (/a/-/ae/). Changes induced in the spectra of the vowels by degradation showed that the impact of reverberation combined with noise was quite different from either condition alone. The recognition performance of participants (n=26) for isolated word stimuli matched the predictions of the frequency analysis. In sentences the recognition of the vowel was strongly influenced by the subsequent context; performance was best with congruent context and worst with incongruent context. The deleterious impact of incongruent context was larger than the helpful impact of congruent context. Incongruent context effects were greatest in noise but were also found in quiet and in reverberation.

ß-1 and ß-2 adrenergic receptor polymorphism and association with cardiovascular response to orthostatic screening.

Variation in the beta-1 and beta-2 adrenergic receptor genes (ADRB1 and ADRB2, respectively) may influence cardiovascular reactivity including orthostatic stress. We tested this hypothesis in a head-up tilt (HUT) screening protocol in healthy young adults without history of syncope. Following brachial arterial catheter insertion, 120 subjects (age 18-40, 72 females, Caucasian) underwent 5min 60° HUT. Polymorphisms tested were: Ser49/Gly and Arg389/Gly in ADRB1; and Arg16/Gly, Gln27/Glu, and Thr164/Ile in ADRB2. Three statistical models (recessive, dominant, additive) were evaluated using general linear models with analysis for each physiologic variable. A recessive model demonstrated a significant association between Arg16/Gly and: absolute supine and upright HR; HUT-induced change in cardiac index (CI), stroke index (SI) and systemic vascular resistance (SVR); and supine and upright norepinephrine values. Blood pressure was not influenced by genotype. Fewer associations were present for other polymorphisms: Ser49/Gly and the change in SI (dominant model), and Arg389/Gly and supine and HUT norepinephrine (additive model). We conclude that in this population, there is a robust association between Arg16/Gly and HUT responses, such that 2 copies of Arg16 increase supine and upright HR, and greater HUT-induced decreases in CI and SI, with greater increases in SVR and norepinephrine. ADRB1 gene variation appears to impact SI and plasma NE levels but not HR. Whether ADRB2 gene variation is ultimately disease-causing or disease-modifying, this study suggests an association between Arg16/Gly and postural hemodynamics, with sympathetic noradrenergic activity affected in a similar direction. This may have implications in the development of orthostatic disorders.