  We propose a simple method to measure acoustic responses using any sounds by
converting them suitable for measurement. This method enables us to use music
pieces for measuring acoustic conditions. It is advantageous to measure such
conditions without annoying test sounds to listeners. In addition, applying the
underlying idea of simultaneous measurement of multiple paths provides
practically valuable features. For example, it is possible to measure
deviations (temporally stable, random, and time-varying) and the impulse
response while reproducing slightly modified contents under target conditions.
The key idea of the proposed method is to add relatively small deterministic
signals that sound like noise to the original sounds. We call the converted
sounds safeguarded test signals.
