Create a 30-second sound piece that combines elements of classical, jazz, and ambient music. The sound piece should have a soothing and stimulating effect on the baby's brain, enhancing their cognitive and emotional development. The sound piece should have the following features: - A clear and catchy melody that repeats throughout the piece, played by a piano or a flute. - A harmonic and rhythmic accompaniment that varies in intensity and complexity, played by a string quartet or a saxophone. - A background layer of soft and subtle sounds that create a sense of space and atmosphere, such as birds chirping, water flowing, or wind blowing. - A smooth and seamless transition between the different sections of the piece, using modulation, tempo change, or fade in/out effects. - A balanced and pleasant mix of the different sound elements, using volume, panning, and equalization techniques.