Is a letterbox always a letterbox? The role of affordances in guiding perceptual categorization.

Classically investigated in the context of judgment tasks about achievable actions, affordances have also been investigated in the context of the stimulus-response compatibility paradigm. Earlier work showed that perceptual categorization performance is significantly faster and more accurate when the orientation of the graspable part of a presented object, and the orientation of the participant's response are compatible, suggesting that the main function of affordances is restricted to action preparation. Here, we investigate the potential role of affordances in the categorization of ambiguous stimuli through a stimulus-response compatibility paradigm. In other words, we investigate if in ambiguous situations, such as ones in which a stimulus may give rise to two percepts, affordances would stabilize perception on one of these two and, therefore, helps in the subsequent categorizations. Two experiments were run, based on the forced-choice stimulus-response compatibility (SRC) paradigm, with a progressive series of ambiguous (bistable) lateral-graspable objects. In Experiment 1, subjects responded by pressing horizontally opposite keyboard keys, while in Experiment 2, the keyboard keys were vertically separated. Experiment 1 found that subjects perceived the initial object in a bistable series for longer, and exhibited greater response stability in compatible than incompatible situations. In Experiment 2, none of these modulations were significant. Overall, our results show that affordances operationalized through a SRC paradigm modulated how subjects categorized ambiguous stimuli. We argue that affordances may play a substantial role in ambiguous contexts by reducing the uncertainty of such situations.

The bassoon tonehole lattice: Links between the open and closed holes and the radiated sound spectrum.

The acoustics of the bassoon has been the subject of relatively few studies compared with other woodwind instruments. One reason for this may lie in its complicated resonator geometry, which includes irregularly spaced toneholes with chimney heights ranging from 3 to 31 mm. The current article evaluates the effect of the open and closed tonehole lattice (THL) on the acoustic response of the bassoon resonator. It is shown that this response can be divided into three distinct frequency bands that are determined by the open and closed THL: below 500 Hz, 500-2200 Hz, and above 2200 Hz. The first is caused by the stopband of the open THL, where the low frequency effective length of the instrument is determined by the location of the first open tonehole. The second is due to the passband of the open THL, such that the modes are proportional to the total length of the resonator. The third is due to the closed THL, where part of the acoustical power is trapped within the resonator. It is proposed that these three frequency bands impact the radiated spectrum by introducing a formant in the vicinity of 500 Hz and suppressing radiation above 2200 Hz for most first register fingerings.

Contact Pressure Between the Vocal Folds in Reinke's Edema: Experimental Observations on an Excised Human Larynx.

OBJECTIVE: To analyze the range of values of the contact pressure between the membranous vocal folds with Reinke's edema and to compare it to those observed in the absence of such a lesion. METHODS: Two human larynges were separately tested on the experimental bench, one of them with a bilateral loose swelling of the vocal folds. Once in a glottal prephonatory configuration, airflow was increased until achievement of self-sustained oscillations while recording aerodynamic, acoustic, electroglottographic data, and contact pressure between the folds. RESULTS: We observed well-documented variations in acoustical parameters, as the decrease of the fundamental frequency and the increase of the phonation threshold pressure. The results of the study also point to a significant increase in the amplitude of the contact pressure in presence of the Reinke's edema, and a lower degree of harmonicity of the produced sounds. CONCLUSION: This is the first report of ex vivo study of a larynx with Reinke's edema. It highlights the increase in the contact pressure during phonation, which possibly contributes to sustain the lesion once it appeared.

Interaction of reed and acoustic resonator in clarinetlike systems.

Sound emergence in clarinetlike instruments is investigated in terms of instability of the static regime. Various models of reed-bore coupling are considered, from the pioneering work of Wilson and Beavers ["Operating modes of the clarinet," J. Acoust. Soc. Am. 56, 653-658 (1974)] to more recent modeling including viscothermal bore losses and vena contracta at the reed inlet. The pressure threshold above which these models may oscillate as well as the frequency of oscillation at threshold are calculated. In addition to Wilson and Beavers' previous conclusions concerning the role of the reed damping in the selection of the register the instrument will play on, the influence of the reed motion induced flow is also emphasized, particularly its effect on playing frequencies, contributing to reduce discrepancies between Wilson and Beavers' experimental results and theory, despite discrepancies still remain concerning the pressure threshold. Finally, analytical approximations of the oscillating solution based on Fourier series expansion are obtained in the vicinity of the threshold of oscillation. This allows to emphasize the conditions which determine the nature of the bifurcation (direct or inverse) through which the note may emerge, with therefore important consequences on the musical playing performances.