Press the key 1 for 1x times speed, press the key 2 for 2x times speed, press the key 3 for 4x times speed, press the key 4 for 6x times speed, press the key 5 for 8x times speed, press the key 6 for 10x times speed, press the 7 key for 12 times speed and so on. Press 0 to mute all sounds
