it allows for rapid and "clean" runs. Multiple hammer-ons and pull-offs together are sometimes also referred to colloquially as "rolls," a reference to the fluid sound of the technique. A rapid series of hammer-ons and pull-offs between a single pair of notes is called a trill. Legato on guitar is commonly associated with playing more notes within a beat than the stated timing, i.e., playing 5 (a quintuplet) or 7 (a septuplet) notes against a quarter-note instead of the usual even number or triplet. This gives the passage an unusual timing and when played slowly an unusual sound. However, this is less noticeable by ear when played fast, as legato usually is. There is a fine line between legato and two-hand finger tapping, in some cases making the two techniques harder to distinguish by ear. Generally, legato adds a more fluid, smooth sound to a passage. Synthesizers In synthesizers legato is a type of monophonic operation. In contrast to the typical monophonic mode where every new note articulates the sound by restarting the envelope generators, in legato mode the envelopes are not re-triggered if the new note is played "legato" (with the previous note still depressed). This causes the initial transient from the attack and decay phases to sound only once for an entire legato sequence of notes. Envelopes reaching the sustain stage remain there until the final note is released. Vocal music In classical singing, legato means a string of sustained vowels with minimal interruption from consonants. It is a key characteristic of the bel canto singing style that prevailed among voice teachers and singers during the 18th century and the first four decades of the 19th century. Usually referred to as the line, a good, smooth legato is still necessary for successful classical singers. In Western Classical vocal music, singers generally use it on any phrase without explicit articulation marks. Usually the most prevalent issue with vocal legato is maintaining the "line" across registers. Popular Music One of the most recognizable legato organ phrases is that at the beginning of "When a Man Loves a Woman (song)" by Percy Sledge. The song was recorded at FAME Studios in Muscle Shoals, Alabama founded by Rick Hall. The organ was played by Spooner Oldham. References Further reading Articulations (music) Italian opera terminology