The study of insect blood-feeding behaviour: 1. Feeding equipment, physical and endogenous factors, dose effect analysis, and diet destination

Experimental techniques that we have found useful during our studies of insect blood-feeding behaviour are reviewed. Some of the principal findings resulting from these techniques are discussed. Where directly applicable, the work of others is included, but no complete review of the subject has been attempted.

The role of the right parietal cortex in sound localization: a chronometric single pulse transcranial magnetic stimulation study.

Auditory spatial functions, including the ability to discriminate between the positions of nearby sound sources, are subserved by a large temporo-parieto-frontal network. With the aim of determining whether and when the parietal contribution is critical for auditory spatial discrimination, we applied single pulse transcranial magnetic stimulation on the right parietal cortex 20, 80, 90 and 150 ms post-stimulus onset while participants completed a two-alternative forced choice auditory spatial discrimination task in the left or right hemispace. Our results reveal that transient TMS disruption of right parietal activity impairs spatial discrimination when applied at 20 ms post-stimulus onset for sounds presented in the left (controlateral) hemispace and at 80 ms for sounds presented in the right hemispace. We interpret our finding in terms of a critical role for controlateral temporo-parietal cortices over initial stages of the building-up of auditory spatial representation and for a right hemispheric specialization in integrating the whole auditory space over subsequent, higher-order processing stages.

Towards an emotion-driven interactive music system: ridging the gaps between affect, physiology and sound generation

Report for the scientific sojourn at the Stanford University from January until June 2007. Music is well known for affecting human emotional states, yet the relationship between specific musical parameters and emotional responses is still not clear. With the advent of new human-computer interaction (HCI) technologies, it is now possible to derive emotion-related information from physiological data and use it as an input to interactive music systems. Providing such implicit musical HCI will be highly relevant for a number of applications including music therapy, diagnosis, nteractive gaming, and physiologically-based musical instruments. A key question in such physiology-based compositions is how sound synthesis parameters can be mapped to emotional states of valence and arousal. We used both verbal and heart rate responses to evaluate the affective power of five musical parameters. Our results show that a significant correlation exists between heart rate and the subjective evaluation of well-defined musical parameters. Brightness and loudness showed to be arousing parameters on subjective scale while harmonicity and even partial attenuation factor resulted in heart rate changes typically associated to valence. This demonstrates that a rational approach to designing emotion-driven music systems for our public installations and music therapy applications is possible.

The spatio-temporal brain dynamics of processing and integrating sound localization cues in humans.

Interaural intensity and time differences (IID and ITD) are two binaural auditory cues for localizing sounds in space. This study investigated the spatio-temporal brain mechanisms for processing and integrating IID and ITD cues in humans. Auditory-evoked potentials were recorded, while subjects passively listened to noise bursts lateralized with IID, ITD or both cues simultaneously, as well as a more frequent centrally presented noise. In a separate psychophysical experiment, subjects actively discriminated lateralized from centrally presented stimuli. IID and ITD cues elicited different electric field topographies starting at approximately 75 ms post-stimulus onset, indicative of the engagement of distinct cortical networks. By contrast, no performance differences were observed between IID and ITD cues during the psychophysical experiment. Subjects did, however, respond significantly faster and more accurately when both cues were presented simultaneously. This performance facilitation exceeded predictions from probability summation, suggestive of interactions in neural processing of IID and ITD cues. Supra-additive neural response interactions as well as topographic modulations were indeed observed approximately 200 ms post-stimulus for the comparison of responses to the simultaneous presentation of both cues with the mean of those to separate IID and ITD cues. Source estimations revealed differential processing of IID and ITD cues initially within superior temporal cortices and also at later stages within temporo-parietal and inferior frontal cortices. Differences were principally in terms of hemispheric lateralization. The collective psychophysical and electrophysiological results support the hypothesis that IID and ITD cues are processed by distinct, but interacting, cortical networks that can in turn facilitate auditory localization.

NIAIC - Medical Device Equipment Alerts (MEDA)

NIAIC - Medical Device Equipment Alerts

NIAIC - Medical Device and Equipment Alerts 2013

Medical Device and Equipment Alerts MDEA Updates - 2013

NIAIC - Medical Device and Equipment Alerts 2012

Medical Device and Equipment Alerts MDEA Updates - 2012

NIAIC - Medical Device and Equipment Alerts 2010

Medical Device and Equipment Alerts MDEA Updates - 2010

NIAIC - Medical Device and Equipment Alerts 2011

Medical Device and Equipment Alerts MDEA Updates - 2011

NIAIC - Medical Device and Equipment Alerts 2009

Medical Device and Equipment Alerts MDEA Updates - 2009

Disability Equipment Services in Northern Ireland Regional Summary (PDF 1815 KB)

March 2003 - main findings of the study, key recommendations and the way forward

Sound objects in time, space and action

SOUND OBJECTS IN TIME, SPACE AND ACTIONThe term "sound object" describes an auditory experience that is associated with an acoustic event produced by a sound source. At cortical level, sound objects are represented by temporo-spatial activity patterns within distributed neural networks. This investigation concerns temporal, spatial and action aspects as assessed in normal subjects using electrical imaging or measurement of motor activity induced by transcranial magnetic stimulation (TMS).Hearing the same sound again has been shown to facilitate behavioral responses (repetition priming) and to modulate neural activity (repetition suppression). In natural settings the same source is often heard again and again, with variations in spectro-temporal and spatial characteristics. I have investigated how such repeats influence response times in a living vs. non-living categorization task and the associated spatio-temporal patterns of brain activity in humans. Dynamic analysis of distributed source estimations revealed differential sound object representations within the auditory cortex as a function of the temporal history of exposure to these objects. Often heard sounds are coded by a modulation in a bilateral network. Recently heard sounds, independently of the number of previous exposures, are coded by a modulation of a left-sided network.With sound objects which carry spatial information, I have investigated how spatial aspects of the repeats influence neural representations. Dynamics analyses of distributed source estimations revealed an ultra rapid discrimination of sound objects which are characterized by spatial cues. This discrimination involved two temporo-spatially distinct cortical representations, one associated with position-independent and the other with position-linked representations within the auditory ventral/what stream.Action-related sounds were shown to increase the excitability of motoneurons within the primary motor cortex, possibly via an input from the mirror neuron system. The role of motor representations remains unclear. I have investigated repetition priming-induced plasticity of the motor representations of action sounds with the measurement of motor activity induced by TMS pulses applied on the hand motor cortex. TMS delivered to the hand area within the primary motor cortex yielded larger magnetic evoked potentials (MEPs) while the subject was listening to sounds associated with manual than non- manual actions. Repetition suppression was observed at motoneuron level, since during a repeated exposure to the same manual action sound the MEPs were smaller. I discuss these results in terms of specialized neural network involved in sound processing, which is characterized by repetition-induced plasticity.Thus, neural networks which underlie sound object representations are characterized by modulations which keep track of the temporal and spatial history of the sound and, in case of action related sounds, also of the way in which the sound is produced.LES OBJETS SONORES AU TRAVERS DU TEMPS, DE L'ESPACE ET DES ACTIONSLe terme "objet sonore" d��crit une exp��rience auditive associ��e avec un ��v��nement acoustique produit par une source sonore. Au niveau cortical, les objets sonores sont repr��sent��s par des patterns d'activit��s dans des r��seaux neuronaux distribu��s. Ce travail traite les aspects temporels, spatiaux et li��s aux actions, ��valu��s �� l'aide de l'imagerie ��lectrique ou par des mesures de l'activit�� motrice induite par stimulation magn��tique trans-cr��nienne (SMT) chez des sujets sains. Entendre le m��me son de fa��on r��p��titive facilite la r��ponse comportementale (amor��age de r��p��tition) et module l'activit�� neuronale (suppression li��e �� la r��p��tition). Dans un cadre naturel, la m��me source est souvent entendue plusieurs fois, avec des variations spectro-temporelles et de ses caract��ristiques spatiales. J'ai ��tudi�� la fa��on dont ces r��p��titions influencent le temps de r��ponse lors d'une t��che de cat��gorisation vivant vs. non-vivant, et les patterns d'activit�� c��r��brale qui lui sont associ��s. Des analyses dynamiques d'estimations de sources ont r��v��l�� des repr��sentations diff��renci��es des objets sonores au niveau du cortex auditif en fonction de l'historique d'exposition �� ces objets. Les sons souvent entendus sont cod��s par des modulations d'un r��seau bilat��ral. Les sons r��cemment entendus sont cod�� par des modulations d'un r��seau du c��t�� gauche, ind��pendamment du nombre d'expositions. Avec des objets sonores v��hiculant de l'information spatiale, j'ai ��tudi�� la fa��on dont les aspects spatiaux des sons r��p��t��s influencent les repr��sentations neuronales. Des analyses dynamiques d'estimations de sources ont r��v��l�� une discrimination ultra rapide des objets sonores caract��ris��s par des indices spatiaux. Cette discrimination implique deux repr��sentations corticales temporellement et spatialement distinctes, l'une associ��e �� des repr��sentations ind��pendantes de la position et l'autre �� des repr��sentations li��es �� la position. Ces repr��sentations sont localis��es dans la voie auditive ventrale du "quoi".Des sons d'actions augmentent l'excitabilit�� des motoneurones dans le cortex moteur primaire, possiblement par une aff��rence du system des neurones miroir. Le r��le des repr��sentations motrices des sons d'actions reste peu clair. J'ai ��tudi�� la plasticit�� des repr��sentations motrices induites par l'amor��age de r��p��tition �� l'aide de mesures de potentiels moteurs ��voqu��s (PMEs) induits par des pulsations de SMT sur le cortex moteur de la main. La SMT appliqu��e sur le cortex moteur primaire de la main produit de plus grands PMEs alors que les sujets ��coutent des sons associ��e �� des actions manuelles en comparaison avec des sons d'actions non manuelles. Une suppression li��e �� la r��p��tition a ��t�� observ��e au niveau des motoneurones, ��tant donn�� que lors de l'exposition r��p��t��e au son de la m��me action manuelle les PMEs ��taient plus petits. Ces r��sultats sont discut�� en termes de r��seaux neuronaux sp��cialis��s impliqu��s dans le traitement des sons et caract��ris��s par de la plasticit�� induite par la r��p��tition. Ainsi, les r��seaux neuronaux qui sous-tendent les repr��sentations des objets sonores sont caract��ris��s par des modulations qui gardent une trace de l'histoire temporelle et spatiale du son ainsi que de la mani��re dont le son a ��t�� produit, en cas de sons d'actions.

Sound Texture Modelling

In the PhD thesis ���Sound Texture Modeling��� we deal with statistical modelling or textural sounds like water, wind, rain, etc. For synthesis and classification. Our initial model is based on a wavelet tree signal decomposition and the modeling of the resulting sequence by means of a parametric probabilistic model, that can be situated within the family of models trainable via expectation maximization (hidden Markov tree model ). Our model is able to capture key characteristics of the source textures (water, rain, fire, applause, crowd chatter ), and faithfully reproduces some of the sound classes. In terms of a more general taxonomy of natural events proposed by Graver, we worked on models for natural event classification and segmentation. While the event labels comprise physical interactions between materials that do not have textural propierties in their enterity, those segmentation models can help in identifying textural portions of an audio recording useful for analysis and resynthesis. Following our work on concatenative synthesis of musical instruments, we have developed a pattern-based synthesis system, that allows to sonically explore a database of units by means of their representation in a perceptual feature space. Concatenative syntyhesis with ���molecules��� built from sparse atomic representations also allows capture low-level correlations in perceptual audio features, while facilitating the manipulation of textural sounds based on their physical and perceptual properties. We have approached the problem of sound texture modelling for synthesis from different directions, namely a low-level signal-theoretic point of view through a wavelet transform, and a more high-level point of view driven by perceptual audio features in the concatenative synthesis setting. The developed framework provides unified approach to the high-quality resynthesis of natural texture sounds. Our research is embedded within the Metaverse 1 European project (2008-2011), where our models are contributting as low level building blocks within a semi-automated soundscape generation system.

Cultiu Podcast

L'objectiu del TFC ��s crear una 'suite' que resolgui tota la l��nia de producci�� d'un podcast. ��s a dir: captura d'un senyal d'audio en directe, transcodificaci��, classificaci��,emmagatzematge i, per acabar, difusi�� per Internet.