SINGER: Pink Floyd

SONG:Empty Spaces

[backwards message:]
"congratulations, you have just discovered the secret message.
please send your answer to 'old pink',
care of the funny farm, chalfont..." - spoken by roger
[...interrupted...]
"roger, caroline's on the phone..." - unknown voice
What shall we use
to fill the empty spaces
where we used to talk?
how shall i fill
the final places?
how can i complete the wall