In conjunction with scent, vocalization appears to play a key role in social interaction. In a fascinating paper to the Journal of Mammalogy, David Macdonald, Paul Stewart and Josephine Wong describe a range of calls recorded during their observation of the badger setts in Wytham Woods. The researchers could identify 16 calls: bark; chirp; chitter; churr; cluck; coo; growl; grunt; hiss; kecker; purr; snarl; snort; squeak; wail; and yelp. A description of the calls and details of when they're made can be found on the Badgerland website. The original sound files (originally hosted on the WildCRU site) are no longer available for download, but WildCRU have put together a video of the calls (see below).
In the paper, Macdonald and his colleagues write that churrs, purrs and keckers are restricted to adults; chirps, clucks, coos, squeaks and wails to cubs; while the remaining eight calls were exhibited by both. In his 1975 opus Grzimek's Animal Life Encyclopedia, the late German zoologist Bernhard Grzimek described a “piercing scream” that is apparently emitted by wounded badger. Grzimek writes:
“This call [referring to a call reported during badger copulation] resembles the death scream of a mortally wounded badger, a sound which is so terrifying that many a hunter has ceased getting badgers after hitting one and hearing the cry.”
While the WildCRU biologists were able to link the acoustic structure of the calls they witnessed to their function, which they inferred from the context in which the call was made, they found no evidence for either alarm calls to conspecifics or the long-range “scream” to which Grzimek refers. Given the absence of loud (and thus long-distance) calls, it is reasonable to assume that vocalization is probably an inherently interpersonal form of communication that is used on a strictly close-range basis (i.e. between individuals in close quarters).