Sampler items allow you to play a sound file. You can adjust a number of parameters. Only files in .wav or .ogg format can be used. If you need to convert sound files, for example from .mp3 format, you can use Audacity <http://audacity.sourceforge.net/>, an excellent open-source sound editor.
Volume between 0 and 100%
Pan turns the right (negative values) or left (positive values) channel down. Setting pan to -20 or 20 completely mutes the right or left channel, respectively.
Pitch indicates the speed at which the sample is played. Values higher than 100% indicate a speed-up, values lower than 100% indicate a slowing down.
Stop after indicates how long the sample should be played. For example, a value of 100ms means that the sample will be stopped after 100ms, regardless of how long the sample is. A value of 0ms means playing the full sample.
Fade in indicates the fade in time for the sample.
Duration indicates the duration of the sampler item, before the next item is presented. This doesn't need to match the length of the sample. For example, the duration of the sampler may be set to 0ms, to advance directly to the next item (e.g., a sketchpad), while the sample continues playing. In addition to a numeric value, you can set duration to 'keypress', to wait for a keyboard press, 'mouseclick', to wait for a mouse click, or 'sound', to wait until the sampler has finished playing.