What technique involves rolling 'r's while playing a brass or woodwind instrument?

The technique that involves rolling 'r's while playing a brass or woodwind instrument is known as flutter tonguing. This technique requires the player to rapidly alternate between tongue articulations, creating a distinctive, fluttering sound similar to the rolling 'r' in vocalizations. It adds a unique texture and expressiveness to the performance, often employed in various styles of music to enhance the character of a piece.

Trilling refers to the rapid alternation between two adjacent notes, which does not involve the tongue's rolling motion. Vibrato is a technique involving the oscillation of pitch, achieved through controlled variations in breath support and embouchure, rather than tongue articulation. Breath control is fundamental for all wind instrument playing, impacting sound quality and technique, but is not specific to producing the 'rolling r' effect. Flutter tonguing, therefore, is the correct answer as it specifically captures the essence of that rolling sound characteristic in woodwind and brass playing.