Empty Spaces lyrics

[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 should I complete the wall?