Auditory model-based estimation of the effect of head-worn devices on frontal horizontal localisation

Auditory localisation accuracy may be degraded when a head-worn device (HWD), such as a helmet or hearing protector, is used. A computational method is proposed in this study for estimating how horizontal plane localisation is impaired by a HWD through distortions of interaural cues. Head-related impulse responses (HRIRs) of different HWDs were measured with a KEMAR and a binaural auditory model was used to compute interaural cues from HRIR-convolved noise bursts. A shallow neural network (NN) was trained with data from a subjective listening experiment, where horizontal plane localisation was assessed while wearing different HWDs. Interaural cues were used as features to estimate perceived direction and position uncertainty (standard deviation) of a sound source in the horizontal plane with the NN. The NN predicted the position uncertainty of localisation among subjects for a given HWD with an average estimation error of 1°. The obtained results suggest that it is possible to predict the degradation of localisation ability for specific HWDs in the frontal horizontal plane using the method.

From Dichoptic to Dichotic: Historical Contrasts between Binocular Vision and Binaural Hearing

Phenomena involving vision with two eyes have been commented upon for several thousand years whereas those concerned with hearing with two ears have a much more recent history. Studies of binocular vision and binaural hearing are contrasted with respect to the singleness of the percept, experimental manipulations of dichoptic and dichotic stimuli, eye and ear dominance, spatial localisation, and the instruments used to stimulate the paired organs. One of the principal phenomena that led to studies of dichotic hearing was dichoptic colour mixing. There was similar disagreement regarding whether colours or sounds could be combined when presented to different paired organs. Direction and distance in visual localisation were analysed before those for auditory localisation, partly due to difficulties in controlling the stimuli. Instruments for investigating binocular vision, like the stereoscope and pseudoscope, were invented before those for binaural hearing, like the stethophone and pseudophone.

Do ideas about function help in the study of causation?

One of Tinbergen's most lasting contributions to the study of behaviour was the distinction he drew between causal, functional, developmental, and evolutionary questions about behaviour. More recently, behavioural ecologists have claimed that understanding the function of behaviour is an important step towards understanding its causes. This claim has, in turn, been criticised for confusing the fundamental distinction that Tinbergen defined. The study of behaviour, however, usually begins by identifying units of behaviour functionally and only then proceeds to causal analysis. Research carried out on four phenomena — disassortative mating by MHC loci, memory for cache sites in food-storing birds, auditory localisation of prey by barn owls, and magnetic orientation — illustrates the contributions made to causal research through understanding the function of behaviour. Understanding function, and sometimes simply a hypothesis about function, defines the causal questions that are asked, identifies novel questions for causal investigation, and sets the criteria that causal explanations must satisfy.