Switching a tone on and off generates broadband transient clicks in distant frequency bands

Evidence

The I-kHz tone burst produces in this bandpass filter a short click, followed by the I-kHz oscillation with very small amplitude; in order to be visible, this amplitude has been multiplied by a factor of four in the figure. The short click at the beginning and at the end of the time function stems from the broadband transient which produces energy in the 4-kHz range at the moment of switching on or off the I-kHz tone burst. — Professor Dr.-Ing. Hugo Fastl, Professor Dr.-Ing. Eberhard, Psychoacoustics- Facts and Models, 216