Pink Floyd - Echoes

"Echoes" is a composition by Pink Floyd including lengthy instrumental passages, sound effects, and musical improvisation. Written in 1970 by all four members of the group (credited as Roger Waters, Richard Wright, Nick Mason, David Gilmour on the original release), "Echoes" provides the extended finale to Pink Floyd's album Meddle. The track has a running time of 23:31 and takes up the entire second side of the vinyl recording.

The composition uses many progressive and unconventional musical effects. The ping sound heard at the beginning of the song was created as the result of an experiment at the very beginning of the Meddle sessions. It was produced through amplifying a grand piano, played by Richard Wright, and sending the signal through a Leslie rotating speaker. Most of the song's musical passages are in the key of C-sharp minor. At seven minutes in, a funk progression in the tonic minor begins. David Gilmour used the slide for certain sound effects on the studio recording, and for the introduction in live performances from 1971-75. A throbbing wind-like sound is created by Roger Waters vibrating the strings of his bass guitar with a steel slide and feeding the signal through a Binson Echorec. The high-pitched electronic 'screams', resembling a distorted seagull song, were discovered by Gilmour when the cables were accidentally reversed to his wah pedal.^[2] After observing the song being created, Nick Mason noted, "The guitar sound in the middle section of 'Echoes' was created inadvertently by David plugging in a wah-wah pedal back to front. Sometimes great effects are the results of this kind of pure serendipity, and we were always prepared to see if something might work on a track. The grounding we'd received from Ron Geesin in going beyond the manual had left its mark."^[2]

- Wikipedia