In my first WhatCulture article (guys, I don't actually believe the Master and the Doctor are the same person... give me a break, I do these articles voluntarily), I discussed the link between River Song and music. To recap if you can't be bothered to read the original, I theorised that music had been played rather more this series to compensate for the lack of another kind of Song, and that when the Doctor said that he could always hear River, maybe he was being literal. Do read the original though. It's a work of staggering artfulness and witty genius. In fact, there are eleven non-Murray Gold songs in Series 7, compared to the three we got each Eleventh Doctor series before that. That's a lot more song to compensate for no Melody. And it's eleven, obviously. In case you missed it, it was the 'Silence in the Library' where Song met her end. The Silence were the ones that tried to separate Song and the Doctor. In 'The Doctor Dances', Nancy keeps a gas-masked soldier asleep with a lullaby, in 'Fear Her', Chloe's mum does the same, and in 'Cold War', Clara sings Duran Duran to herself in the face of the Ice Warrior. The opening lyric of Abigail's Song is "When you're alone, silence is all you know", and it really does sum up the Whoniverse and music: melody and song are used to soothe and comfort, whilst silence is symbolic of danger, death or loneliness. The very last thing the Ood tell the Tenth Doctor is that the universe will sing him to sleep. But if the Ood had however gone with 'Best Song Ever' by One Direction, maybe Ten would've preferred the Silence.