Description:
<jats:p>Very often one wants to track one type of noise embedded in another noise. In addition, the noises may be nonstationary. For example, suppose one wants to track in time and or space a reverberation type noise that is embedded in an background ambient noise. Many of the techniques that have been developed for deterministic signals do not work for such situations. We discuss various methods that have been developed to track noises and to separate noises and to estimate the parameters of non-stationary noises. We will show that a particular effect method to understand nonstationary noises is to study them in phase space. We give a number of examples.</jats:p>