The sound of crickets in the autumn night is quite inspiring. Only male crickets can make this clear and beautiful sound, by rubbing their serrated wings against each other.
There are four kinds of cricket chirps: an attracting song (for females), a courting song (when a female is near), an aggressive song (when a male is near) and a copulatory song (after a successful mating). Each song is played at a different volume and pitch.
As all insects are cold-blooded, they are heavily affected by temperature. In the case of crickets, this is reflected in the frequency of chirps, which increases proportionately to the temperature. Using this, one can calculate the air temperature from the number of chirps a Snowy Tree cricket makes (count the number of chirps in 14 seconds plus 40 to get the temperature in Fahrenheit).
Finally, cricket chirps cannot be heard via cellphones. This is because a cricket chirp is usually around 6500Hz frequency, while most cellphones operate at a maximum of 3300Hz.