Towards the dream of autonomous human-robot interactions, a robot endowed with a reliable hearing sense is essential. Nowadays, a hearing sense is generally composed of auditory capabilities such as sound localization, along with sound separation, speech processing and auditory scene analysis, that build up the topic of robot audition. In this research area, a particular attention has been given to sound source localization, certainly because it is the first step of auditory-based interaction. The typical approach of sound localization consists in transposing the knowledge in psychoacoustics and physiology into an artificial hearing system that extracts auditory cues. The settings generally assume that the sensors and sources of interest are static. The auditory cues such as the interaural time difference and the interaural level difference or the spectral notches, provide information about the direction of arrival of the sound in the horizontal and the vertical plane. 

The efficiency of the localization process depends exclusively on the accuracy of the extracted auditory cues. However mimicking the human hearing system happens to be complex in realistic configurations. Perception and more particularly auditory cues are influenced by the shape of the body (head, pinna, torso...) along with the acoustic conditions (acoustic of the room, noise, reverberation). The sensitivity to auditory events is variable for each individual and each location. As a consequence, even the most complex artificial auditory systems can be deployed in controlled environment only. Real world configurations, that include dynamic scenes, reverberation, noises, degrade drastically the accuracy of the auditory cues and at the same time the localization performance. As a result, sound source localization considering binaural setup was not achievable in real-world environments.

My work adressed motion strategies linked to the auditory perception, in a binaural context, with a central focus on the following question Do robots need to localize sound sources to engage into an interaction ? As an answer of this question, my work defined auditory-based interactions as tasks modelled in a sensor-based framework. This framework, that I defined as aural servo (AS), does not localize sound sources. A task is characterized by a state of measurements to satisfy, that generally corresponds to a particular pose of the robot. For instance, in AS, a homing task consists in positioning the robot for satisfying given conditions defined by a set of auditory measurements, while a localization-based approach requires to extract the bearing angle and the distance to the sound source, before moving the robot to the correct location. In the AS paradigm, the motion of the robot is generated in real time, through a control loop based on auditory cues measured on the fly. Velocity inputs of the robot are obtained by modeling the relationship between the variation of given auditory cues and of the sensors motion. In this way, my approach principally relies on the variation of these cues instead of their intrinsic values. Consequently the localization step is skipped and the modeling of the adverse acoustic conditions or the effect of the body/head are not required to be modeled. Hence, it is even possible to complete tasks with erroneous auditory cues as long as the variation of these cues remains consistent.