Active noise compression systems

This paper presents a new concept of narrowband and broadband active noise compression (ANCom) systems which improves the conventional active noise eq ualization (ANE) technique to meet some practical requirements. By using a variable equalization coefficient, the narrowband ANCom system can automati cally switch among the four different operating modes of narrowband ANE, ac cording to the primary noise power. As a result, it can "compress" the narr owband noise into a desired power range when the primary noise power varies drastically. Compared to a conventional broadband ANE system, the novel br oadband ANCom system not only has the ability to shape the residual noise p ower spectrum, but can also compress the residual noise power into a predet ermined dynamic range as the narrowband AN-Com does. Theoretical analyses a re conducted for both the narrowband ANCom and broadband ANCom systems. Sim ulation results show that the proposed algorithms work well in both static and dynamic situations.