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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

AN EVALUATION OF ACOUSTIC FEEDBACK AND HUMAN PERFORMANCE

Britwum, Kwadwo O. 01 December 2021 (has links) (PDF)
Feedback procedures are an important class of operant behavior change methods used in a wide variety of settings. One innovative method of providing immediate feedback adapted from the animal literature is through the use of an acoustical stimulus, such as a clicker. Methods utilizing this response contingent delivery of acoustic feedback in humans is commercially referred to as TAGteaching. Several studies have documented the effectiveness of this teaching procedure with various human populations. Despite the successes, very little is known of the environmental manipulations necessary to produce desirable effects; and if these effects sustain when this procedure is implemented in clinical settings. Moreover, several authors have asserted that the acoustic stimulus functions like a conditioned reinforcer, however no explicit pairing procedures are traditionally implemented with humans, to establish the functions of contingent deliveries of the acoustic stimulus. The purpose of the current study was twofold; first this study sought to evaluate the role of textual instructions in establishing the functions of response contingent acoustic feedback using a laboratory task. Secondly, this study sought to evaluate the extent to which instructions and acoustic feedback, produce changes in staff and client behaviors in a clinical setting. Study one was conducted across 40 college students and evaluated the role of instructions in establishing the functions of contingent acoustic feedback in the context of a Multistep Experimental Task (MSET). The MSET was adopted from a previous laboratory evaluation of TAGteach (Smith & Lambert, 2014). Participants were assigned to four different experimental groups for both a within-subject and a between-group analysis of performance. Results indicated improved performance for all participants who received both instructions and contingent acoustic feedback, whereas three participants who received acoustic feedback only showed similar improvements. Study two was conducted across three staff participants and sought to evaluate an intervention comprised of in-situ instructions and response contingent acoustic feedback to teach staff to use Behavior Specific Praise procedures (BSP) with clients. Results from a multiple-baseline-across staff design revealed that the intervention increased staff’s rates of BSP in this clinical setting. Additionally, intervention effects were maintained during one to three-week probes. The intervention also maintained client correct responding across different targeted behavior chains. Staff members also rated the acoustic feedback procedure as more worthwhile, helpful, relevant, pleasant, and less disruptive than their typical feedback methods. Both findings provide useful data to support the design and implementation of acoustic feedback procedures in clinical settings. They also provide preliminary data to clarify the antecedent conditions necessary to establish the functions of contingent acoustic feedback.
2

Détection et localisation de cible en guide d'onde : application au concept de barrière acoustique à l'échelle du laboratoire / Detection and localization of target in shallow water in the framework of the acoustic barrier problem at the laboratory scale

Marandet, Christian 21 October 2011 (has links)
Cette thèse démontre expérimentalement à l'échelle du laboratoire la détection et la localisation, en transmission, d'une cible de taille de la longueur d'onde. La configuration expérimentale correspond à un guide d'ondes ultrasonique limité par deux réseaux émetteur-récepteur. Deux réseaux coplanaires enregistrent dans le domaine temporel la matrice de transfert du guide d'ondes entre chaque couple émetteur-récepteur. En invoquant le principe de réciprocité, un algorithme de Double Formation de Voies est simultanément exécuté sur les réseaux émetteur et récepteur. Ce traitement d'antennes permet de projeter les échos acoustiques plusieurs fois réverbérés en un ensemble de rayons acoustiques, qui sont définis par angles leurs angles d'émission et de réception. La comparaison réalisée entre l'amplitude de chaque rayons acoustique avec et sans cible dans le guide d'onde permet, par effet d'ombre, de détecter de la cible. La localisation est réalisée à travers la résolution d'un problème inverse en utilisant les rayons acoustiques extraits de la double formation de voies. L'utilisation de noyau de sensibilité utilisant le phénomène de diffraction pour chaque rayon acoustique fournit la localisation et une signature de la cible. Des résultats expérimentaux sont présentés en présence de vagues en surface. L'utilisation de l'effet Larsen dans la cadre de la barrière acoustique est également envisagée pour son extrême sensibilité aux variations du milieu. / This thesis demonstrates experimentally at the laboratory scale the detection and localization, in transmission, of a wavelength-sized target in a shallow ultrasonic waveguide between two source-receiver arrays in the framework of the acoustic barrier problem. Two coplanar arrays record in the time-domain the transfer matrix of the waveguide between each pair of source-receiver transducers. Invoking the reciprocity principle, a time-domain double-beam-forming algorithm is simultaneously performed on the source and receiver arrays. This array processing projects the multireverberated acoustic echoes into an equivalent set of eigenray, which are defined by their launch and arrival angles. Comparison is made between the amplitude of each eigenray without and with a target for detection in the waveguide. Localization is performed though inversion problem using all of the eigenrays extracted from double beamforming. The use of the diffraction-based sensitivity kernel for each eigenray provides both the localization and the signature of the target. Experimental results are shown in the presence of surface waves. The use of the acoustical feedback in frame of the acoustic barrier problem is also considered, for its extreme sensibility to medium variation.

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