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Title Source Separation for Feedback Cancellation in Hearing Aids
Author Ma, Guilin (Acoustic Technology, Department of Electrical Engineering, Technical University of Denmark, DTU, DK-2800 Kgs. Lyngby, Denmark)
Supervisor Agerkvist, Finn T. (Acoustic Technology, Department of Electrical Engineering, Technical University of Denmark, DTU, DK-2800 Kgs. Lyngby, Denmark)
Luther, Jim (GN Resound)
Institution Technical University of Denmark, DTU, DK-2800 Kgs. Lyngby, Denmark
Thesis level Master's thesis
Year 2006
Abstract This thesis addresses the problem of feedback cancellation in hearing aids using source separation techniques. Feedback oscillation (when a hearing aid whistles) is a major issue with hearing aids. It limits the maximum gain that can be achieved. The biggest barrier in solving this problem is the bias in feedback cancellation. A great number of algorithms are proposed during the last two decades. However, even in the most advanced hearing aids today, it still cannot be banished completely. This thesis attacks the feedback problem from a new angle. It is the first attempt to use source separation techniques in feedback cancellation system. Existing algorithms on feedback suppression and source separation were reviewed thoroughly to find the fundamental limitation of feedback cancellation system and the main direction of selecting desirable source separation techniques. Three different algorithms are investigated later. The first two are based on literature. The performance is not satisfactory. The last one, a novel algorithm proposed in this project, itself is source separation technique dealing with the very difficult case when the problem is underdetermined and with correlated sources, which is unfortunately exactly the case when feedback cancellation is regarded as a source separation problem. The performance of the algorithm is satisfactory when the two sources have comparable variance. Two strategies are proposed to incorporate the proposed source separation technique in feedback cancellation system. The performance is evaluated with real speech and music on a standard feedback canceller and the most advanced feedback canceller invented by GN Resound. The first strategy is proved to be successful in enhancing the stability of the hearing aids on both feedback cancellers.
Imprint Technical University of Denmark (DTU) : Kgs. Lyngby, Denmark
Pages 98
Fulltext
Original PDF GuilinMa_thesis.pdf (2.14 MB)
Admin Creation date: 2009-11-12    Update date: 2009-11-12    Source: dtu    ID: 252332    Original MXD