Learning spatial hearing via innate mechanisms
Fig 6
Bootstrapping procedures for different learning contexts.
Scenario 1: bootstrapping with a limited head rotation range. (A) The agent estimates sound locations within the rotation range using an innate Teacher, and estimate sound locations beyond the rotation range using a learned localiser as Teacher. Gradient estimation with innate Teacher can be done by any method, e.g. surrogate gradient or reinforcement learning. (B) Expanding the already learned localisation range (green area) into the “inferrable area” (blue) by combining head rotation and bootstrapping on existing localisation range, constructing an array of Teachers and Students during the process, by replacing the old Teacher with the learned localiser after each expansion. (C) The process by which the learned part of the localisation range expands to fill the whole space during training. Scenario 2: using a unilateral rather than bilateral Teacher circuit. (D) The bootstrapping process, showing how a gradient can be estimated with a unilateral circuit by pointing the right ear toward the sound source to find the loudest response. (E) The unilateral circuit with an abstract memory unit. (F) 2D response map of the right ear, showing the peak response when the right ear is pointed toward the sound. Scenario 3: extending from a circular localiser to a spherical localiser. (G) The process by which the circular procedures can be extended to spherical procedures by composing them for azimuth and then elevation. (H) Illustration of azimuth and elevation.