Click any red arrow. Make sure your audio is working and you can hear. Click to say you can hear the tone. Click anywhere on the blue full-page GO. Click [PLAY] to be able to choose any item to hear by clicking its button. Click [AUTO] to hear them all in random order. Click [GUESS] to challenge your knowledge. Use each as you like. GUESS until perfect: you can do it. Best of all, when you did it, you get the knowledge that you did it. It's a superpower!