Acoustic MIMO Systems

2.4 Summary

In this chapter, we described four signal models for acoustic systems according to the number of inputs and outputs. The models were presented in both the time and frequency domains and will be frequently used throughout the rest of this book. The characteristics of acoustic channels were investigated and covered not only conventionally well-recognized features (e.g., linearity and shift-invariance, FIR, time-varying channels, frequency selectivity, invertibility, etc.) but also those characteristics that have not received adequate attention until very recently (like multichannel diversity, the common-zero problem, and sparseness). At the end of this chapter, we discussed facilities for directly measuring acoustic impulse responses and the image method for their simulation.