Never tested separately
Clairaudience
Clairaudience is the claimed ability of hearing voices or sounds beyond ordinary hearing. It has never been tested as a distinct ability: Untested as a distinct ability.
The experiment
None isolating it
Auditory experience without an external source is well documented in ordinary psychology. A 2011 meta-analysis by Beavan, Read and Cartwright pooled 17 studies across nine countries and put lifetime prevalence in the general population at 13.2% — one person in eight, most of them with no mental illness at all. That is a real, replicated finding, and it is not the same claim as clairaudience: hearing a voice is common, and hearing one that knows something you could not is what would need testing.
The gap between those two is where this term lives. Roughly one in eight people will hear something with no external source at some point, so the experience needs no special explanation — it is ordinary enough to be near universal across cultures. What has never been tested is whether any of those voices carry information the listener had no way to obtain. Not once, in the whole literature, has that specific question been put to an experiment. The claim is not disproven; it has simply never been asked properly, while the underlying experience has been studied extensively and turns out to be normal.
Where the word comes from
Nineteenth century, alongside clairvoyance.
Terms in this field are younger than they sound. Most were coined between 1840 and 1930, in the Spiritualist and Theosophical revivals, and then presented as ancient. Dating them is the cheapest reality check available.