The artwork may symbolize someone being surrounded by sound, as if it were echoing around them. It may also symbolize walls around the person, which makes sense due to the lyrics making a reference to sound bouncing off of walls.
The lyrics suggest a scenario where someone has been in solitary confinement for too long, driving him or her, to insanity, where "you will never ever get to me in here." Another possible scenario is a direct link between the lyrics present on this song and "Demon Seed" ("You feel me breathe" on "Echoplex" vs. "I can hear it breathe"). They could also be extremely literal, referring to the solitude of wherever frontman Trent Reznor comes up with his music.
The bridge to the coda of the song features wind synthesizers similar to the one used in the introduction of "Wish," but do not appear to be the same sound.
Echoplex is also the name of a specific brand of reverb units.
This is the only official version of the song.
Echoplex (Live At Rehearsals)
This version of the song was released online via nin.com and PitchforkTV. It was filmed and recorded in the band's rehearsal space in mid 2008 and directed by Rob Sheridan. Josh Freese uses a Jazzmutant Lemur to create the opening drum loop before joining in himself with a different rhythm on top of the loop for the second verse. It also features on The Slip, on a DVD of rehearsal footage.
"Echoplex" was performed on the encore of every show of the Lights In The Sky Tour, and was frequently used in the Wave Goodbye Tour. During the Lights In The Sky Tour, Reznor used a large touch screen at the back of the stage to simulate a drum machine to play the song's recognisable beat.
Nice and high and far apart Just like they said I built this place with broken parts Just like they said You chip away the old version of you You'd be surprised at what you can do I'm safe in here Irrelevant Just like they said My voice just echoes off these walls You feel me breathe I am watching you I see it all The many ways you can't get to me I see it all I see the Hell you put yourself through Oh the things I could do (if I wanted to) My voice just echoes off these walls My voice just echoes off these walls I don't need anything at all My voice just echoes off these walls And I just slowly fade away You will never ever get to me in here