Aeroacoustic techniques in engineering were pioneered by engineers investigating noise generation and acoustic signatures in military and defense applications. In civil industries, aeroacoustic noise is increasingly a hot topic for engineers working in ground / air transport, industrial machinery, concert hall acoustics, environmental conditions, as well as complex fluid-structure interactions. Our increased awareness of the adverse effects of noise annoyance has led to aero-acoustically generated noise being identified as a critical design variable in modern engineering design...
Wind noise is a complex phenomenon spanning aerodynamics, acoustics, and the physiology of human hearing. The amount experienced depends on factors like: 1) speed, 2) riding position, 3) turbulence, and so on. Wind noise impacts the ability to hear surrounding sounds.
The theory of aero-acoustics, the physics describing wind noise, is difficult and not complete. Location of the sources of wind noise via measurement is very challenging and requires specialized test facilities and equipment. Understanding the theory and its implications for measurement and analysis is critical for designing the most effective wind noise reduction products for cyclists.
Exhaustive testing ensures that our products are the most effective of their kind on the market. We use precision audio recording equipment, spectral analysis software, CT (hot-wire) anemometers / pressure probes, and high resolution imaging tools. In addition to 'stress testing' in 'designed use' environments, we incorporate laboratory testing in custom built facilities, including:
• Two open jet quiet wind tunnels with controllable speed and turbulence.
• A hydrodynamic (water) flume using fluorescein dye for flow visualization.
Our products are road and laboratory tested at speeds up to 40 mph - with variable turbulence.
The importance of materials engineering cannot be overstated. We incorporate characteristics like texture, porosity, permeability (flow resistance), resilience, etc. Effectively combining external and internal flow requirements demands unique material characteristics and blending for optimal performance. In addition, we hold utility patent #US 9078482 (Sound Permeable Wind Noise Reduction Device).
Acoustic transparency is critical for situational awareness when cycling. While some products incorporate materials that block or deflect sound transmission - including desired sounds, we focus on optimizing the signal to wind noise ratio. Clear communications, and pinpointing the location of sound sources, are important. Our products are tested for acoustic transparency / sound source localization.
"The average person facing a 21 mph wind experiences wind noise at an intensity of 92 dB."
(Experiments on the Noise Heard by Human Beings when Exposed to Atmospheric Winds, NTNU, Trondheim, Norway)
"Innovative safety technologies will continue to play an important role in the way
cyclists interact in traffic... particularly as vehicles become quieter." (Safety Science 2018)
"I turn my head about 20-30° to reduce wind noise when talking or listening to someone when I ride.
However, this probably isn't a good idea for long conversations or watching where you're going."
(comment from a major cycling forum)
TrueRTA Audio Spectrum Analysis
Elise Fajen, Fred M. Fajen, Adrienne Fajen
A company by the name of Wind-Blox makes a 'wind and noise blocker' product that attaches to the leading straps on a cycling helmet and, as the name suggests, blocks wind. Introduced about a year after Cat-Ears, Wind-Blox originally measured 'a 47% reduction in (wind noise) loudness'. Shortly thereafter, the advertised effectiveness increased to 'up to 80%'... and then a miraculously accurate 80.2%. Having performed exhaustive wind noise testing, we figured that the miraculously accurate 80.2% claim was either a mistake or a marketing ploy to sell products...
The claim that Wind-Blox 'invented' this WNR concept might be more than a little inaccurate.
Any patent claims by Wind-Blox are probably meaningless given the existence of Prior Art.
"Prior Art is any evidence that your invention is already known. Prior Art does not need to exist physically or be commercially available. It is enough that someone, somewhere, sometime previously has described or shown or made something that contains a use of technology that is very similar to your invention." (USPTO)