High quality, correctly fitted earplugs are essential for scooter riding, and it is a good idea to wear them on every ride without fail. High levels of noise are proven to be very stressful and can cause a loss of concentration, and the noise can quickly and permanently damage your hearing, and hearing loss is irreversible.
Many riders have indeed suffered permanent hearing loss and moderate to severe tinnitus (tinnitus is also known as ringing of the ears), due to exposure to unhealthy noise levels. Hearing loss is permanent, so take the utmost care in protecting your hearing.
So there's no getting around the fact that scooter riding creates high noise levels, and the discussion isn't about whether a helmet is noisy or quiet. There is no such thing as a quiet helmet, period; there are basically only two types of scooter helmets: loud and louder.
It's essential to note that every rider and every scooter will have a different experience and comfort level when it comes to acceptable noise levels. There are basically three types of helmet noise: low frequency, or "booming" noise; mid-tone, "wind rustling" noise; and high frequency "whistling" type noise.
Individual tolerance for these noises vary with each rider. The most annoying noises are the low frequency or "booming" type, which are usually caused by turbulence around the lower portions of the helmet around the chin and neck area.
This noise can be greatly exacerbated by certain types of windscreens that can cause turbulence around the lower and rear portions of the helmet.
So, please get some earplugs and wear them!