As you may already know, the SI unit for frequency is Hertz (Hz); an event that repeats once per second has a frequency of 1 Hz. According to most sources, the human hearing (frequency) range is between 20 Hz and 20,000 Hz (bats can hear up to 100,000 Hz!).
Note: Some jurisdictions have laws requiring passengers on bicycles to be at least one year old. Usually by age 12 months parents can start checking with the child's physician to see if they have the neck development to safely go for a bike ride.elevance. Rating Newest Oldest. Best Answer: Obviously a child can't be on a bike until they can safely wear a helmet. http://www.helmets.org/little1s.htm Nobody we have met in the injury prevention field recommends taking an infant of less than 12 months in a bicycle child seat, trailer, sidecar or any other carrier.
That explains why you will not find a child helmet on the market sized for a tiny tot. You certainly do not want to ride with a bare-headed child, and in some places it is illegal. In fact, several states have laws against taking children under one year of age on a bicycle, even with a helmet. Parents love their babies and love their bicycles, so it is natural to want to put the two together.