Whistling shares a common tongue with speech: bioacoustics from real-time MRI of the human vocal tract

Most human communication is carried by modulations of the voice. However,
a wide range of cultures has developed alternative forms of communication
that make use of a whistled sound source. For example, whistling is used as
a highly salient signal for capturing attention, and can have iconic cultural
meanings such as the catcall, enact a formal code as in boatswain’s calls or
stand as a proxy for speech in whistled languages. We used real-time magnetic
resonance imaging to examine the muscular control of whistling to describe a
strong association between the shape of the tongue and the whistled frequency. This bioacoustic profile parallels the use of the tongue in vowel
production. This is consistent with the role of whistled languages as proxies
for spoken languages, in which one of the acoustical features of speech
sounds is substituted with a frequency-modulated whistle. Furthermore, previous evidence that non-human apes may be capable of learning to whistle
from humans suggests that these animals may have similar sensorimotor
abilities to those that are used to support speech in humans.