You will often find an option setting button that you can press when playing most slot machines in land based venues and when you click on that button one of the options that will become available to you is an audio setting or volume button. You will also find on all slot machines a pay table button and if at any time, you wish to check what the payouts are on any of the possible winning combinations that you can spin in then make sure you give that button a click the pay table will often also show you how the bonus games can be triggered too!