Create a 30-second sound piece that combines elements of classical music, nature sounds, and baby laughter. The sound piece should have a soothing and stimulating effect on the baby's brain, while also being fun and engaging. The sound piece should have the following structure: - Start with a gentle melody played by a piano or a harp, accompanied by the sound of running water and bubbles. - Introduce a flute or a violin that plays a more complex and playful melody, along with the sound of a rubber duck squeaking and a baby giggling. - Add a cello or a bassoon that plays a deeper and richer harmony, along with the sound of a splash and a baby cooing. - End with a crescendo of all the instruments and sounds, followed by a soft lullaby and a baby saying "bye-bye".