Noise levels under motorcycle helmets can be very high. Daily noise exposures of working motorcyclists may regularly exceed 90 dB(A).
The measurements in the wind tunnel showed the main source of noise to be the turbulence at the edge of the windscreen's wake acting on the helmet. Low windscreens direct the turbulence to the base of the helmet, and modifications to improve the helmet seal around the neck can reduce noise levels on motorcycles with low windscreens.
Wind tunnel tests with a flying helmet containing active noise reduction earmuffs demonstrated that noise levels as low as 70 dB(A) at 80 km/h and 80 dB(A) at 115 km/h were achievable at the ear. We recommend you consider wearing earplugs under the helmet.
How to Care for Motorcycle Helmet Visors
Executive summary about motorcycle helmets by Kayar Sprang
Tinted visors help shield your eyes from the sun and blinding vehicle lights.
Things You'll Need:
1. Soft, clean cloths
2. Mild baby shampoo
3. Rain-X® X-treme Clean™
1. Not all helmet visors can be cleaned the same way. Manufacturer's instructions vary.
2. Wash the visor immediately after each use to easily remove dust, dirt and grime. Some manufacturers only allow their visors to be cleaned with warm water and a soft cloth because chemicals can harm the surface. Rinse it thoroughly and dry it to a streak-free shine with a clean cloth.
3. Clean the helmet visor with mild baby shampoo, water, and a soft cloth if the manufacturer allows you to use soap. Rinse the visor off with clean water first. Then, place a few drops of shampoo in warm water. Swish it around, then wash the motorcycle visor with a soft cloth. Pat it--don't rub. Dry with a clean cloth.
4. Use a cleaning product like Clear Shot Visor Motorcycle Helmet Visor and Lens Cleaner if the manufacturer allows it. This kit includes a spray cleaning fluid and two microfiber cleaning cloths.
5. Treat the motorcycle helmet visor with a water repellent and protectant such as Rain-X® X-treme Clean™ if the manufacturer allows.
6. Store the visor in a soft bag when it's not in use to protect it from scratches and damage.
7. Set the visor down on its edges--never on its face--when it's detached from the helmet.
8. Keeping a visor clean will go far in reducing scratches. Never clean a motorcycle helmet visor with an abrasive cleaner.