Forty years ago, two astronomers in New Jersey heard a noise on a radio telescope that confirmed the idea that the universe began with a massive explosion, some 14 billion years earlier. That noise, pervading uniformly the sky everywhere and in all directions was the oldest signal from the Universe, the echo of the big bang itself. The modern Universe however is lumpy, with stars, galaxies and clusters of galaxies. These lumps must have been there in the early Universe and grew subsequently by gravity: the echo of the big bang, should be modulated, like a song, like a melody that pervaded the newborn universe. It has now been 15 years since astronomers first "heard" the sound of the baby universe. Since then, thanks to ever more sophysticated instruments, we have learned how to interpret it, and learned about age, size, geometry and composition of the Universe. The sounds have many more nuances and harmonics that we hope to be able to interpret with future instruments. I will present an overview of recent and future attempts at understanding the sound of the baby universe.