From “ear” to there: a review of biorobotic models of auditory processing in lizards

Abstract

The peripheral auditory system of lizards has been extensively studied, because of its remarkable directionality. In this paper, we review the research that has been performed on this system using a biorobotic approach. The various robotic implementations developed to date, both wheeled and legged, of the auditory model exhibit strong phonotactic performance for two types of steering mechanisms-a simple threshold decision model and Braitenberg sensorimotor cross-couplings. The Braitenberg approach removed the need for a decision model, but produced relatively inefficient robot trajectories. Introducing various asymmetries in the auditory model reduced the efficiency of the robot trajectories, but successful phonotaxis was maintained. Relatively loud noise distractors degraded the trajectory efficiency and above-threshold noise resulted in unsuccessful phonotaxis. Machine learning techniques were applied to successfully compensate for asymmetries as well as noise distractors. Such techniques were also successfully used to construct a representation of auditory space, which is crucial for sound localisation while remaining stationary as opposed to phonotaxis-based localisation. The peripheral auditory model was furthermore found to adhere to an auditory scaling law governing the variation in frequency response with respect to physical ear separation. Overall, the research to date paves the way towards investigating the more fundamental topic of auditory metres versus auditory maps, and the existing robotic implementations can act as tools to compare the two approaches.

Reinforcement Learning for Bio-Inspired Target Seeking

“…Another common example of Braitenberg vehicles is the one implementing phonotaxis through microphones [19], for instance with a sound source placed at some height h 0 above the ground. It can be seen that, according to the inverse-distance law, the sound intensity will fulfil the conditions for the stimulus function.…”

Sound source localization and segregation with internally coupled ears: the treefrog model

“…However, the influence of the lung input on the auditory coupling is not well understood in Hyla (or in any other group of frogs) and awaits further studies. In terms of acoustic input through the lung and other pathways, the biophysics of the internally coupled middle ears of frogs is far more complicated than the lizard middle ear, which can be modeled efficiently as a two-input system (Carr et al 2016; Shaikh et al 2016). Realistic models of auditory coupling in the treefrog ear will have to include the properties of the lung input, as well as other extratympanic inputs (Aertsen et al 1986; Narins 2016).…”

Animals and ICE: meaning, origin, and diversity

“…Since in his days the corresponding key notions were not yet available (van Hemmen 2014), the dream was soon over. Now they are at hand and Shaikh et al (2016) show how ICE can lead to more efficient and robust sound localization in robotics.…”