Enjoy and repeat everyday, then your ear for music is trained. Congraturate your kid over again and again when he/she answer correctly!
Get the in-game character to eat food with the same sound as you hear at the beginning of the game. If you memorize the chord of each food, try to answer without listning to the sound of it.
Change at Setteings screen. You can try and enjoy from any level. But your training will go on smoothly and find this app very interesting if you start at Beginner and proceed to the next when you answer 90% correctly.