Wind noise is a complex phenomenon spanning aerodynamics, acoustics, and the physiology of human hearing.  The amount of noise generated depends on factors like 1) speed, 2) riding position, 3) turbulence, and so on.  At moderate cycling speeds, wind noise can impact the ability to hear surrounding sounds.

​

Hydrodynamic Pressure Fluctuations (Pseudo-sound):  This refers to the direct, non-propagating pressure variations inherent within the turbulent airflow immediately surrounding and impinging upon the ear canal opening.  These localized, chaotic pressure fluctuations directly stimulate the eardrum.

Aerodynamic Sound Generation (Dipole Acoustic Noise):  As airflow separates and sheds vortices from the various geometries of the ear (e.g., tragus, pinna), helmet edges, and straps, these unsteady fluid-structure interactions generate propagating acoustic waves.  These radiated sound waves then travel to and into the ear canal.

 

Understanding the complexities of Ear-Wind Noise requires specialized testing / analysis.