  The Hopf oscillator is a nonlinear oscillator that exhibits limit cycle
motion. This reservoir computer utilizes the vibratory nature of the
oscillator, which makes it an ideal candidate for reconfigurable sound
recognition tasks. In this paper, the capabilities of the Hopf reservoir
computer performing sound recognition are systematically demonstrated. This
work shows that the Hopf reservoir computer can offer superior sound
recognition accuracy compared to legacy approaches (e.g., a Mel spectrum +
machine learning approach). More importantly, the Hopf reservoir computer
operating as a sound recognition system does not require audio preprocessing
and has a very simple setup while still offering a high degree of
reconfigurability. These features pave the way of applying physical reservoir
computing for sound recognition in low power edge devices.
