To facilitate communications among passengers in a large vehicle, an appropriate system with microphones, loudspeakers, and amplifiers is needed. However, a signal processing algorithm is required to avoid feedback and instability. Borrowing from speech-reinforcement research, the authors use a room-modeling adaptive feedback-cancellation approach that combines the Prediction Error Method and adaptive filtering. And, by including a suppressor filter, the system can be extended to a dual-channel scenario that supports bidirectional communications, where additional feedback paths must be considered with respect to the single-channel case study. In order to achieve low latencies and real-time processing, the partitioned block frequency domain adaptive filter algorithm has been adopted. Voice-activity and double-talk detectors have been included as well. Computer simulations in various acoustic conditions have shown the effectiveness of this approach.
A Real-time Dual-Channel Speech Reinforcement System for Intra-Cabin Communication / Faccenda, Francesco; Squartini, Stefano; Principi, Emanuele; Gabrielli, Leonardo; Piazza, Francesco. - In: AES. - ISSN 1549-4950. - Volume 61, Issue 11:(2013), pp. 889-910.