Sluchatkovy chranic s digitalnim systemem aktivniho snizovani hluku.

The aim of the thesis was a design and realisation of an adaptive active noise control (ANC) system in a headset. The realised active hearing protector (AHP) system exploits an adaptive ANC system used for modified a commercial headset. The penetrated broadband audible noise is attenuated by 8 dB maximum and the dominant frequency component can be attenuated even more -by 29 dB in the frequency range of 70-700 Hz. The principle of an ANC system is described, the audible noise is defined and classified and its measurement is described. The basic ANC system structures and features including the adaptive ANC and their maximal theoretical noise suppression follow. Analogue, digital and adaptive filters are described. The measurement methodology of headset features critical for an ANC system design is described, too. Analyses of the system's particular parts influence on the quality of noise suppression are presented with the design criteria of electronic parts and system parameters setting. Adaptive models length determination is presented. The SIMULINK model of an ANC system for a headset and the MATLAB model structure having possibility to process digital record of a real noise are presented. The influence of the headset position on the headset sensitivity and the influence of the dependence of the reference microphone distance on the signal coherence is illustrated by measured transfer functions and impulse characteristics. Other measurements results are attached, too. The thesis contains a summary of equations describing theoretical limits of an ANC system in the headset and recommendations for the design of such a system.Available from STL Prague, CZ / NTK - National Technical LibrarySIGLECZCzech Republi