A numbers station is a type of shortwave radio station characterized by unusual broadcasts, reading out lists of numbers or incomprehensible coded messages. The voices are often created by speech synthesis and are transmitted in a wide variety of languages. The voices are usually female, although sometimes men's or children's voices are used. Some voices are synthesized and created by machines; however, some stations used to have live readers. Many numbers stations went off the air due to the end of the Cold War in ****, but many still operate and some have even continued operations but changed schedules and operators.