Proceedings of meetings on acoustics. Acoustical Society of America最新文献

A recent study from our lab showed that normal-hearing adults rely on cues in the region of 0.5-1 kHz for target talker localization and speech-in-speech recognition when the target can only be identified based on spatial cues. The present study evaluated whether similar weights are observed for speech-in-speech recognition that relies on access to vowels or consonants, given differences in the distributions of cues required for vowel and consonant recognition. Spectral weights were estimated by filtering stimuli into 1-octave-wide bands, dispersing those bands on the horizontal plane, and assessing the association between each band's position and participants' responses. Data were obtained for two tasks: 1) localization of the target relative to the masker (left vs. right), and 2) closed-set word recognition, where response alternatives differed either with respect to the initial consonant, vowel, or final consonant. As observed previously, weights for both tasks peaked at 0.5-1 kHz for all three stimulus sets. This result is consistent with the idea that the spatial cues supporting spatial release from masking are similar regardless of the frequency regions containing speech cues required for correct recognition of the target.

The vocal folds experience repeated collision during phonation. The resulting contact pressure is often considered to play an important role in vocal fold injury, and has been the focus of many experimental studies. In this study, vocal fold contact pattern and contact pressure during phonation were numerically investigated. The results show that vocal fold contact in general occurs within a horizontal strip on the medial surface, first appearing at the inferior medial surface and propagating upward. Because of the localized and travelling nature of vocal fold contact, sensors of a finite size may significantly underestimate the peak vocal fold contact pressure, particularly for vocal folds of low transverse stiffness. This underestimation also makes it difficult to identify the contact pressure peak in the intraglottal pressure waveform. These results showed that the vocal fold contact pressure reported in previous experimental studies may have significantly underestimated the actual values. It is recommended that contact pressure sensors with a diameter no greater than 0.4 mm are used in future experiments to ensure adequate accuracy in measuring the peak vocal fold contact pressure during phonation.

In this work, the feasibility of ultrasound elastography to evaluate age-related muscle atrophy is investigated. Ultrasound elastography is used to assess muscle stiffness alterations of bovine shoulder samples during aging treatment. Of particular interest is to investigate the decrease in muscle stiffness due to two potential reasons: (1) decrease in collagen fibers; and (2) mechanical breakdown of the muscle fascia (the soft tissue component of connective tissue surrounding muscle). Two methods of aging treatments are employed: (1) chemical treatment, and (2) percussion treatment. Areas of the bovine shoulder samples studied were the triceps brachii and infraspinatus. The chemically treated bovine samples demonstrated significant alterations in muscle stiffness under ultrasound in comparison to percussive treatment. The significance of these results will be discussed.