Effect of wind on self-audition of human voice

Abstract

During one's speech, the human auditory system continuously monitors one's own voice and subconsciously adjusts it based on the way it is heard. Part of the sound produced in the human vocal tract radiates from the mouth, propagates in the air around the head, and reaches the ears externally. It is therefore affected by the background air conditions, such as the wind, which, in turn, may impact the way one hears oneself.

This thesis investigates the influence of wind around the human head on the sound propagation from the mouth to the ears. The effect is examined using computer simulations and measurements. The simulations, which are limited to a two-dimensional horizontal cross-section of a model head, are implemented using finite element numerical methods in COMSOL Multiphysics software. The background airflow around the head is modelled using the RANS-based SST turbulence model, and the simulated background flow parameters are used in a linearised Navier-Stokes aeroacoustics simulation. The measurements are conducted on a cylindrical measurement rig with a loudspeaker and microphones attached. The rig is placed on the roof of a moving van to imitate a horizontal airflow around a cross-section of the human head. The effect is studied for wind speeds from 6 m/s to 24 m/s in the upwind (incident on the face) and downwind (incident on the back) directions.

Simulation and measurement results demonstrate that sound radiated from the position of the mouth to the location of the ears is attenuated in the upwind scenario and amplified in the downwind case. The amplification and attenuation depend on the wind speed, so the effect is most prominent in the fastest winds studied. It also depends on the sound frequency: the lowest frequencies are impacted the most (within a few decibel range), while the difference vanishes in the higher frequencies (from around 1-4 kHz in the simulations and measurements presented). The results are in line with previous theoretical and empirical descriptions of the upstream amplification phenomena. The effect might influence the perceived loudness of the fundamental frequency of one's own voice and the first formants of the phonemes, which are essential properties of human speech.