Abstract: A method is disclosed which includes receiving an incoming time-varying signal as ambient signal, applying a signal cancellation filter to the incoming time-varying signal to thereby generate an attenuated version of the incoming time-varying signal, selectively choosing one or more selected classes of signals to be broadcasted while other signals are to be attenuated, continually applying the incoming time-varying signal to a classifier to identify presence of the one or more selected classes in the incoming time-varying signal, adding a snippet of a pre-recorded signal associated with each of the identified classes to thereby generate a string of signal snippets associated with the identified classes, and repeating in a loop, combining the attenuated version of the received time-varying signal with the repeated string of signal snippets and broadcasting the combination.