Advances in recording technology have opened our ears to a world of sound that is difficult to detect. Ants are social insects and have elaborate communication methods both through the use of chemicals and the use of sound. Ants, like many insects are capable of stridulation- creating sound by rubbing body parts together.
The abdominal constriction of the Hymenoptera, originally an adaptation for stinging, is further adapted in ants for sound production. Rather than a single constriction of the abdomen like most other Hymenoptera families possess, ants have two constrictions. This creates an organ, the petiole that can produce sound by rubbing against end of the abdomen (which in ants is called the gaster).
In some ant species, the gaster has a series of ridges that can be rubbed against a scraper on the petiole. This motion, similar to running a file across the teeth of a comb, creates vibrations, that can be transmitted either through the ground or through the air. Roberta Gibson, from WildAboutAnts, has a great post on ant stridulation with links to information and insect sound files.
What do ants have to say? Probably quite a bit, but it will take much study to learn their code.