Keith Jarrett is famous for his vocalizations © Olivier Bruchez (Flickr)

About fifteen seconds into this recording of El Dorado, Erroll Garner starts making the noise. It’s a kind of low, guttural humming, and it runs through the entire piece. Sometimes it seems like the melody line or harmony, other times it feels totally disconnected, tangential to the music. Garner drifts from scatting, humming, and half-singing into groans and exclamations. At a certain point it sounds like somebody muttering—maybe a drunk at a bar. We found out that these sounds he’s making have a name: involuntary vocalizations.

There is some dispute over whether the sounds are truly “involuntary,” if the musicians have to make these noises to play the way that they do. Many famous jazz pianists make the sounds too—Bud Powell and Oscar Peterson to name a couple. If you listen closely you can hear the noises on a bunch of jazz albums, like the ones in the links above. In other records the pianists are vocalizing, but you can’t make it out because of how the session was recorded. While many jazz pianists make some noise, perhaps the most conspicuous vocalizer is Keith Jarrett.

His vocalizing is almost too much to believe. Check out the whole Tokyo concert in 1984. Jarrett’s grunts, squeals, and tuneless singing accompanied that whole performance, and have continued throughout his career. He describes his vocalizations as interactions with the music, as opposed to reactions to it.

Jazz pianists aren’t the only ones who involuntary vocalize. Some classical pianists, like Glenn Gould, did it. Gould claimed these auditory occurrences were unconscious. When Gould was a child, his piano teacher tried to cut this idiosyncrasy, but nothing seemed to work. Gould’s humming has been called “Alien Conversations.” Some classical purists feel it ruins his most famous recordings, even though you can barely hear him.