Articles by Riccardo Hofer in JoVE
Hemi-laryngeal Setup for Studying Vocal Fold Vibration in Three Dimensions Christian T. Herbst1,2, Vit Hampala1, Maxime Garcia2,3, Riccardo Hofer2, Jan G. Svec1 1Voice Research Lab, Department of Biophysics, Faculty of Science, Palacky University Olomouc, 2Laboratory of Bio-Acoustics, Dept. of Cognitive Biology, University of Vienna, 3ENES Lab, NEURO-PSI,CNRS UMR 9197, Université Lyon/Saint-Etienne, France This paper introduces a protocol for the preparation of hemi-larynx specimens facilitating a multi-dimensional view of vocal fold vibration, in order to investigate various biophysical aspects of voice production in humans and non-human mammals.
Other articles by Riccardo Hofer on PubMed
Primate Drum Kit: a System for Studying Acoustic Pattern Production by Non-human Primates Using Acceleration and Strain Sensors Sensors (Basel, Switzerland). | Pubmed ID: 23912427 The possibility of achieving experimentally controlled, non-vocal acoustic production in non-human primates is a key step to enable the testing of a number of hypotheses on primate behavior and cognition. However, no device or solution is currently available, with the use of sensors in non-human animals being almost exclusively devoted to applications in food industry and animal surveillance. Specifically, no device exists which simultaneously allows: (i) spontaneous production of sound or music by non-human animals via object manipulation, (ii) systematical recording of data sensed from these movements, (iii) the possibility to alter the acoustic feedback properties of the object using remote control. We present two prototypes we developed for application with chimpanzees (Pan troglodytes) which, while fulfilling the aforementioned requirements, allow to arbitrarily associate sounds to physical object movements. The prototypes differ in sensing technology, costs, intended use and construction requirements. One prototype uses four piezoelectric elements embedded between layers of Plexiglas and foam. Strain data is sent to a computer running Python through an Arduino board. A second prototype consists in a modified Wii Remote contained in a gum toy. Acceleration data is sent via Bluetooth to a computer running Max/MSP. We successfully pilot tested the first device with a group of chimpanzees. We foresee using these devices for a range of cognitive experiments.
The Physiology of Oral Whistling: A Combined Radiographic and MRI Analysis Journal of Applied Physiology (Bethesda, Md. : 1985). | Pubmed ID: 28839006 The fluid mechanics of whistling involve the instability of an air jet, resultant vortex rings, and the interaction of these rings with rigid boundaries (2,4). Experimental models support the hypothesis that the sound in human whistling is generated by a Helmholtz resonator, suggesting that the oral cavity acts as a resonant chamber bounded by two orifices, posteriorly by raising the tongue to the hard palate, and anteriorly by pursed lips 2,2,3). However, the detailed anatomical changes in the vocal tract and their relation to the frequencies generated have not been described in the literature. In this study, videofluoroscopic and simultaneous audio recordings were made of subjects whistling with the bilabial (i.e., "puckered lip") technique. One whistling subject was also recorded using magnetic resonance imaging. As predicted by theory, the frequency of sound generated decreased as the size of the resonant cavity increased; this relationship was preserved throughout various whistling tasks and was consistent across subjects. Changes in the size of the resonant cavity were primarily modulated by tongue position rather than jaw opening and closing. Additionally, when high-frequency notes were produced, lateral chambers formed in the buccal space. These results provide the first dynamic anatomical evidence concerning the acoustic production of human whistling.