Where does trill collide?

In phonetics a trill is a consonant produced when an active articulator (the tongue tip, the uvula, or the lips) is held loosely in the airstream so that it vibrates and briefly closes the vocal tract several times in quick succession, as in the rolled Spanish [r] or the French uvular [ʀ]. The vibration is aerodynamic, not a series of deliberate taps. Ladefoged and Maddieson's The Sounds of the World's Languages surveys the trills found across languages. The referent is a manner of articulation defined by self-sustaining vibration, unrelated to a keyboard ornament or to birdsong beyond the shared name.[1]

Unit

A speech sound produced by the vibration of an articulator in the airstream

Recovery means

Not applicable

Measured by

Classified by place of articulation and the number of vibratory cycles, checked acoustically on the speech waveform

In birdsong a trill is a rapid series of repeated song units, and producing one forces a trade-off: a bird can repeat notes quickly or sweep across a wide frequency range, but doing both at once strains the vocal apparatus. Podos showed that this performance limit shapes which trills evolve across a songbird family, so trill rate and frequency bandwidth together index vocal skill. The referent is a measurable feature of an animal's vocal signal, a distinct construct from the musician's ornament or the phonetician's consonant that happen to share its name.[2]

Unit

A repeated sequence of song notes, indexed by rate and frequency bandwidth

Recovery means

Not applicable

Measured by

Quantified from spectrograms by trill rate and frequency bandwidth, often read against a performance limit