Video: Katy Perry song stops baby crying One mother seems to have found the secret to changing her baby's mood in an instant - she uses the power of Katy Perry. The baby instantly cheers up when the artist's Dark Horse track begins playing. August 6 2014 at 09:42am Related Stories Comment Guidelines Please read our comment guidelines. Login and register, if you haven’ t already. Write your comment in the block below and click (Post As) Has a comment offended you? Hover your mouse over the comment and wait until a small triangle appears on the right-hand side. Click triangle () and select "Flag as inappropriate". Our moderators will take action if need be.