Voiceless retroflex trill

The voiceless retroflex trill is a sound that has been reported to occur as a diaphoneme of /ʂ/ in the Maldivian language.^[1] Although the tongue starts out in a sub-apical retroflex position, trilling involves the tip of the tongue and causes it to move forward to the alveolar ridge; this means that the retroflex trill gives a preceding vowel retroflex coloration the way other retroflex consonants do, but the vibration itself is not much different from an alveolar trill.

Wahgi has a similar trilled allophone of its lateral flap, [𝼈̥r̥].