The song's signature opening was born from a happy accident. Keyboardist Richard Wright played a single high note on a grand piano that was accidentally fed back through a . This created the famous "underwater" sonar sound that defines the track's intro. 3. Collaborative Writing
: The eerie, screaming sounds in the middle section were created by David Gilmour reversing a wah-wah pedal. Echoes - Pink Floyd
: Roger Waters stated the lyrics were an attempt to describe the human potential for empathy . Live at Pompeii The song's signature opening was born from a happy accident