This is the big benefit of DCC - realistic sounds. Some decoders come with a loudspeaker that synchronises particular actions with realistic noise, the most obvious being the ‘chuffing’ sound that changes as speed increases. Other functions, often initiated by the keypad, include sounds like whistles or horns, wheel spin, clanking, air pumps - even station announcements. It is possible to add sounds or re-allocate buttons by altering the CVS. This means you do need to read the manual or you could simply beg or bribe a friendly DCC expert!