Head movement and its relation to hearing

Abstract

Head position at any point in time plays a fundamental role in shaping the auditory information that reaches a listener, information that continuously changes as the head moves and reorients to different listening situations. The connection between hearing science and the kinesthetics of head movement has gained interest due to technological advances that have increased the feasibility of providing behavioral and biological feedback to assistive listening devices that can interpret movement patterns that reflect listening intent. Increasing evidence also shows that the negative impact of hearing deficits on mobility, gait, and balance may be mitigated by prosthetic hearing device intervention. Better understanding of the relationships between head movement, full body kinetics, and hearing health, should lead to improved signal processing strategies across a range of assistive and augmented hearing devices. The purpose of this review is to introduce the wider hearing community to the kinesiology of head movement and to place it in the context of hearing and communication with the goal of expanding the field of ecologically-specific listener behavior.

Keywords: auditory spatial processing; augmentative and alternative communications systems; head movement; head-kinematics; hearing aids; listening intention.

Figure 1

(A) The relative position of the center-of-mass and angle-of-rotation on the sagittal plane; nodding motion shown as a rotation around the Y-axis, with a maximum range of 170°(Θ). (B) The center-of-mass and angle-of-rotation on the axial plane; shaking motion shown as a rotation around the Z-axis, with a maximum range of motion of 160° (Φ). (C) Pitch, Yaw and Roll of the angle of rotation and the relative location of the center of mass. FP, Frankfort plane; AM, Auditory Meatus; IA, Interaural axis; blue circle, axis of rotation; red circle, center of mass.

Figure 2

Diagram showing how head orientations move on Listing’s plane using a Fick Gimbal system. The Fick Gimbal system accounts for head movement that occurs along two planes (Θ = pitch, Φ = yaw) by considering all movement on the roll (rho) axis equal to zero. Listing’s plane is formed between the yaw and pitch axes and lies at the intersection for all the axes, or the axis of rotation. Movement from the initial (i) position to the final (f) position on the pitch and yaw axes occurs on Listing’s plane.

Figure 3

Shows movements in the vertical (VT), medio-lateral (ML) and anterior–posterior (AP) motions for the head (green) and pelvis (blue) in normal gait for a healthy young adult. Figure marks the points of left and right heel strikes (HS) and toe off [TO; from Brodie et al., 2014].

Figure 4

Diagram of the gait cycle tracing the movements of a leg through the stance, swing, and double support phases. Gray: right leg; Black: left leg (adapted from: https://clinicalgate.com/assessment-of-gait/).

Figure 5

Segmented average angular orientation for the trunk and the head for level, ascending and descending paths. Gray: right arm and leg; Black: left arm and leg [ɵ = 8.5°; adapted from Cromwell, 2003].