Behavior during transitions in classrooms is an area in need of additional supports in order for teachers to effectively manage classrooms. Extended transition durations, particularly transition periods between one activity and another are related to problem behavior among children in educational settings. This study evaluated the use of acoustical feedback aimed to improve transition behaviors of elementary school students, using a multiple-baseline design across participants. Teachers were trained to implement the acoustical feedback procedure. Data on teacher treatment fidelity, student transition behavior (transition duration and problem behavior), generalization probes, and social validity were collected to examine the feasibility and potential efficacy of acoustical feedback. The results indicated that the participating teachers successfully implemented the acoustical feedback procedures with high levels or moderately high levels of fidelity and their implementation of the intervention was successful in reducing problem behavior and transition duration for all three participating children. Support for generalization was strong for two teachers and their students and minimal for one teacher and her student.

SAAB has developed an autonomous underwater vehicle that can mimic a conventional submarine for military fleets to exercise anti-submarine warfare. The AUV actively emits amplified versions of received sonar pulses to create the illusion of being a larger object. To prevent acoustic feedback, the AUV must distinguish between the sound to be actively responded to and its emitted signal. This master thesis has examined techniques aimed at preventing the AUV from responding to previously emitted signals to avoid acoustical feedback, without relying on prior knowledge of either the received signal or the signal emitted by the AUV. The two primary types of algorithms explored for this problem include blind source separation and adaptive filtering. The adaptive filters based on Leaky Least Mean Square and Kalman have shown promising results in attenuating the active response from the received signal. The adaptive filters utilize the fact that a certain hydrophone primarily receives the active response. This hydrophone serves as an estimate of the active response since the signal it captures is considered unknown and is to be removed. The techniques based on blind source separation have utilized the recordings of three hydrophones placed at various locations of the AUV to separate and estimate the received signal from the one emitted by the AUV. The results have demonstrated that neither of the reviewed methods is suitable for implementation on the AUV. The hydrophones are situated at a considerable distance from each other, resulting in distinct time delays between the reception of the two signals. This is usually referred to as a convolutive mixture. This is commonly solved using the frequency domain to transform the convolutive mixture to an instantaneous mixture. However, the fact that the signals share the same frequency spectrum and are adjacent in time has proven highly challenging.