Relate frequency, wavelength, speed and period of a wave.
Every periodic wave obeys the relationship v = fλ, where v is the wave speed, f the frequency, and λ the wavelength. The frequency is how many wave cycles pass a point each second, and the wavelength is the distance between successive crests. Their product is the speed at which the wave pattern travels.
The period T is the time for one full cycle and is simply the reciprocal of the frequency, T = 1/f. This calculator takes a frequency and wavelength and returns the wave speed and period. The same formula applies to sound, light, water, and any other wave.
The frequency stays fixed because it is set by the source. The speed changes with the medium, so the wavelength adjusts to keep v = fλ true.
About 343 m/s at 20°C. It increases with temperature.