A glissando is a musical composition tool and playing technique that sounds like a smooth slide from one note to the next. On paper, it appears to be a squiggly line connecting the starting note and the note on which the slide should end. Glissandi is the plural form of glissando. The gliss is well-known in George Gershwin’s “Rhapsody in Blue,” which features a clarinet sliding up to the piece’s first sustained note. The trombone, which uses a set of sliding tubes to move the instrument smoothly from note to note, is best known for its sliding notes.
Continuous and discrete, also known as chromatic, are the two most common types. The continuous form is a smooth slide through notes played on an instrument that can move from note to note without stopping. Trombone, theremin, and unfretted string instruments like violins are examples of instruments that can play a continuous gliss. Some woodwind and brass instruments can also play a nearly continuous glissando bending the notes with a special embouchure, or mouth position.
Discrete or chromatic glissandi feature rapid note changes with audible note divisions within the glissando. This type of gliss is commonly used not because the slide isn’t supposed to be smooth, but because the instrument’s mechanics prevent it. It looks like a continuous gliss when written in musical notation, and the instrumentalist is supposed to assume that the slide should be played as smoothly as the instrument allows. A glissando on a fretted instrument would be a discrete glissando because the frets on the neck cause the string to stop on different notes. The majority of people are familiar with this type of gliss from piano slides like those heard in Jerry Lee Lewis’ “Great Balls of Fire.”
The portamento is a similar technique that involves bending or sliding the transition between notes. Many people believe that a portamento and a glissando are the same thing, while others believe that a portamento occurs when sliding between two notes and a glissando occurs when moving through multiple notes. According to some composers, the portamento is the sliding between two notes that occurs in each note movement of a gliss. The portamento is more commonly used in vocal music, whereas the gliss is more commonly used in instrumental music, especially jazz.