Taps and flaps (such as R and Ó ) are usually voiced, and are therefore to be seen as being very brief voiced plosives. Trills, too, such as the tongue-tip trill r and the uvular trill { are usually voiced, and we find the strange situation that these sounds are doubly periodic: they are periodic as a result of the vocal fold vibration, and also periodic because of the regular (though much slower) vibration of one of the articulators.