The TSoundPlayTone structure.

 // SoundPlayTone
 TSoundPlayTone struct
  Result                sbyte       // The function call result, always NO_ERR.
  Frequency     word        // The tone frequency.
  Duration      word        // The tone duration in milliseconds.
  Loop          byte        // If true, loops forever.
  Volume                byte        // The sound level. Valid values range from 0 to 4.
 TSoundPlayTone ends

See the Tone constants group for Frequency values. See the Time constants group for Duration values.