The present study is an attempt to obtain, from two groups of students, useful facts with which to evaluate the most effective method of presenting educational materials to junior-high-school students. The study is an attempt to measure and evaluate the achievement made in social studies, reading comprehension, and vocabulary in 1949 and 1950. The following questions form the basis for the present study: What method is best for the purpose of presenting materials to a class? Which method helps to solve the problem of the student most effectively? By which method is greater achievement made? If the two methods prove of equal value, then how much achievement may be attributed to the use of each method?

The purpose of this study is to determine the effectiveness of the use of filmstrips as an aid in teaching reading to a group of first grade children in the Tom Bean Consolidated School. A further purpose, and probably the most important as it deals with the ultimate objective of education, is the effect that visual aid has upon the behavior of boys and girls.

The problem of this investigation was two-fold: first, to obtain general information on auditory and visual aids and their apparent values in the schoolroom; and second, to find out to what extent these aids were used in eighty representative schools of Texas during 1945-1946.

De entre los sistemas de reproducción de sonido 3D, Wavefield Synthesis (WFS) presenta una serie de ventajas sobre el resto, principalmente en lo que respecta al gran realismo y sensación de inmersión acústica que proporciona. Otra gran ventaja adicional, es que la zona útil de escucha es muy amplia, superando al resto de sistemas disponibles en la actualidad. La teoría de WFS fue propuesta a finales de los 80 y principios de los 90, no siendo hasta el siglo XXI cuando se han puesto en marcha los primeros prototipos de estos sistemas, aunque muchos aspectos no contemplados en la teoría inicial siguen siendo en la actualidad retos importantes. La presente tesis aborda el estudio de la implementación de los sistemas de WFS aportando soluciones prácticas a las limitaciones tecnológicas que presentan estos sistemas, así como otra serie de problemas de implementación y funcionamiento en tiempo real que, aunque en una primera instancia no se describen como limitaciones físicas, suponen un problema a superar cuando se busca un sistema que funcione eficientemente. El objetivo final de esta tesis es aportar soluciones que contribuyan al desarrollo de un sistema de WFS totalmente funcional, por lo que durante su desarrollo ha sido necesario encontrar soluciones particulares y originales a multitud de problemas de diferente índole. Esta serie de problemas proviene por un lado de las limitaciones físicas de WFS y por otro de la implementación práctica del sistema. Por otro lado también se ha trabajo en los aspectos computacionales relacionados con la implementación en tiempo real de sistemas de WFS, los cuales necesitan una gran potencia de cálculo para dicho funcionamiento en tiempo real sin cortes ni grandes latencias. Este último se ha tratado de forma rigurosa dedicando un capítulo completo para su análisis y propuesta de soluciones eficientes y efectivas en coste. / Bleda Pérez, S. (2009). Contribuciones a la implementación de sistemas Wave Field Synthesis [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/6685

This study investigated automobile drivers' ability to localize auditory and haptic (touch) alarms in terms of speed and accuracy. Thirty-two subjects, balanced across age (20-30 years old and 60-70 years old) and gender, participated in the study. Subjects were screened for minimum hearing of 40 dB for 500 Hz through 4000 Hz auditory tones, and maximum bilateral hearing differences of 10 dB. The experiment consisted of subjects identifying the target location of an alarm while driving a 2001 Buick LeSabre at 55 mph in light traffic. Four alarm modes were tested: 1) an auditory broadband alarm, 2) a haptic seat, 3) a combination of the haptic and the auditory alarm modes, and 4) a combination of the haptic alarm mode with a non-directional auditory alarm played from the front speakers of the vehicle. The alarms were evoked from eight target locations: the front-left, front, front-right, right, back-right, back, back-left, and left. The target locations of the auditory alarm mode existed around the interior of the car cabin using the vehicle's stock sound system speakers. The haptic alarm target locations existed in the bottom of the driver seat using an eight-by-eight grid of actuators. The experimenter evoked the alarms while subjects drove along a two-lane highway, and the alarms were not associated with any actual collision threat. Subjects were instructed to quickly identify the location of the alarm by calling them out, while being as correct as possible. Their choice response time and target location selection was recorded. The alarms were presented approximately every minute during fifteen-minute intervals over the duration of two and a half hours. Subjects completed questionnaires regarding their preference to the alarm modes. Under the conditions investigated, subjects localized the haptic alarm mode faster and more accurately than the auditory alarm mode. Subjects performed equally well with the haptic alarm mode and the two auditory and haptic combination alarm modes in terms of speed and accuracy in identifying their location. Subjects did express a preference for the addition of the auditory component to the haptic alarm mode, perhaps owing to a heightened sense of urgency. However, subjects preferred the haptic alarm mode on its own in response to hypothetical false alarm questions, perhaps because it was less annoying. Alarm mode discriminability was believed to affect localization accuracy and response time owing to its effect on the likelihood of correctly identifying a target location and the attention resources required to differentiate adjacent target locations. / Master of Science

We introduce Sonifind, a micro guidance system implemented on a smartphone that uniquely integrates computer vision and spatial audio intended to assist users who are visually impaired. Currently, micro guidance systems require head-mounted displays and various hardware, limiting their practicality for everyday use. Our system employs an off-the-shelf computer vision library and a smartphone to interpret the user's surroundings and provide intuitive spatial audio cues for real-time guidance. We conducted a between-subjects study with sighted, blindfolded participants to evaluate the learnability, performance, and user satisfaction of Sonifind using two different versions of the system to further inform our ongoing design considerations. We found that the first version of our system (2D Feedback System) with directional (yaw) and depth (translation) audio cues resulted in quicker learnability but worse overall performance. In the second version of our system (3D Feedback System) with vertical axis guidance (pitch), we observed greater user satisfaction but a larger learning curve. These findings suggest that Sonifind has the potential to provide an effective and user-friendly navigation aid for non-sighted individuals, facilitating greater independence and mobility.

Québec Université Laval, Bibliothèque 2014

Thesis (PhD (Electrical and Electronic Engineering))--University of Stellenbosch, 2009. / Although the Class D topology offers several advantages, its use in audio amplification has previously been limited by the lack of competitiveness in fidelity compared to its linear counterparts. During the past decade, technological advances in semiconductor technology have awakened new interest since competitive levels of distortion could now be achieved. The output stage of such an amplifier is the primary limiting factor in its performance. In this dissertation, four non-ideal effects existing in this stage are identified and mathematically analysed. The analytical analysis makes use of a well-established mathematical model, based on the double Fourier series method, to model the imperfections introduced into a naturally sampled pulsewidth modulated waveform. The analysis is complemented by simulation using a strategy based on Newton’s numerical method. The theory is verified by a comparison between the analytical-, simulated- and experimental results.

No description available.

Résumé : La synthèse de champs sonores est un domaine de recherche actif trouvant de nombreuses applications musicales, multimédias ou encore industrielles. Dans ce dernier cas, la re- construction précise du champ sonore est souhaitée, ce qui implique de répondre à un certains nombre de questionnements scientifiques. À l’aide de réseaux de microphones et de haut-parleurs, la captation, la synthèse et la reconstruction précise de champs sonores sont théoriquement possibles. Seulement, pour des applications pratiques, la disposition des haut-parleurs et l’influence acoustique du lieu de restitution sont des facteurs cruciaux à prendre en compte pour s’assurer de la bonne reconstruction du champ sonore. Dans ce contexte, cette thèse de doctorat propose des méthodes et des techniques pour la captation, la transformation et la reconstruction précise de champs sonores en trois dimen- sions en se basant sur la méthode ambisonique d’ordre élevé. Une configuration sphérique pour le réseau de microphones et de haut-parleurs est proposée. Elle suit un maillage de Lebedev à cinquante points qui permet la captation et la reconstruction du champ sonore jusqu’à l’ordre 5 avec le formalisme ambisonique. Les limitations de cette approche, tel le repliement spatial, sont étudiés en détails. De plus, une opération de transformation du champ sonore est présentée. Elle est établie dans le domaine des harmoniques sphériques et permet d’effectuer un filtrage directionnel avant le décodage pour privilégier certaines directions dans le champ sonore, suivant une fonction de directivité choisie. Pour la re- construction, une approche originale, également établie dans le domaine des harmoniques sphériques, permet de prendre en compte l’influence acoustique du lieu de restitution, ainsi que les défauts du système de restitution. Ce traitement permet alors d’adapter la synthèse de champs sonores au lieu de restitution, en conservant le formalisme théorique établi en champ libre. Finalement, une validation expérimentale des méthodes et des tech- niques développées au cours de la thèse est faite. Dans ce contexte, une suite logicielle de synthèse et traitement en temps-réel des champs sonore est développée. / Abstract : Sound field synthesis is an active research domain with various musical, multimedia or industrial applications. In the latter case, the accurate reconstruction of the sound field is targeted, which involves answering several scientific questions. Using arrays of microphones and loudspeakers, the capture, synthesis and accurate reconstruction of sound fields are theoretically possible. However, for practical applications, the arrangement of the loud- speakers and the acoustic influence of the restitution room are critical factors to consider in order to ensure the accurate reconstruction of the sound field. In this context, this thesis proposes methods and techniques for the capture, transforma- tions and accurate reconstruction of sound fields in three dimensions based on the Higher Order Ambisonics (HOA) method. A spherical configuration for the array of microphones and loudspeakers is proposed. It follows a fifty-node Lebedev grid that enables the capture and reconstruction of the sound field up to order 5 with HOA formalism. The limitations of this approach, such as the spatial aliasing, are studied in detail. A transformation op- eration of the sound field is also proposed. The formulation is established in the spherical harmonics domain and enables a directional filtering on the sound field prior to the decod- ing step. For the reconstruction of the sound field, an original approach, also established in the spherical harmonics domain, can take into account the acoustic influence of the restitution room and the defects of the playback system. This treatment then adapts the synthesis of sound fields to the restitution room, maintaining the theoretical formalism established in free field. Finally, an experimental validation of methods and techniques developed in the thesis is made. In this context, a digital signal processing toolkit is de- veloped. It process in real-time the microphones, ambisonics, and loudspeaker signals for the sound field capture, transformations, and decoding.