The Muse rocker - who is expecting his first child with the 32-year-old actress this summer - explained his "mellow sounds" have already been making the tot kick, and based on their success he is thinking of incorporating them into his next album.
He said: "I'm already getting the vibraphone out and the Wurlitzer - these nice sort of twinkling high nice sort of mellow sounds that makes the baby kick and stuff.
"So I've got a feeling I'll incorporate those sounds into the next album a little bit."
However, Matt could be singing lullabies to his Offspring a lot in the future, as Kate - who also has a seven-year-old son, Ryder, with ex-husband Chris Robinson - recently admitted she wishes she could be pregnant "all the time", and already can't wait to be expecting again.
She said: "I already can't wait to have another one. Seriously? I love being pregnant. Gosh, I could be pregnant all the time."