This song is learned by link by investigating the Marine Research facility. While exploring, you'll have to rescue Lulu's seven Zora eggs. After you've saved them, they will attempt to teach you the New Wave Bossa Nova. To learn the song, you'll need to be a Zora and take out your guitar.
After you've learned the song, return to Lulu and play the song for her. This will reassure her about the eggs and she will regain her voice. When she does, they'll begin to sing and the Great Turtle will move, allowing access to the temple beyond.
