Design of a time-domain acoustic contrast control for broadband input signals in personal audio systems

The acoustic contrast control (ACC) approach provides a simple strategy to focus sound on a designed target area in a personal audio system. All of the traditional ACC approaches have been designed in the frequency domain, and then transformed into the time domain through the application of an inverse Fourier transform. Therefore, the broadband contrast performance of the traditional ACC approach is not optimum. Especially, when the length of the control filter is short, the traditional approach may have poor contrast performance at non-control frequencies. This study proposes a novel method that can achieve the optimum broadband contrast performance, which also maintains a good frequency-response consistency by introducing the response variation constraints to improve sound quality. Experimental results demonstrate the effectiveness of the new method.