Update 536-console-sound.markdown

Author: Joe7M

_build/reference/536-console-sound.markdown

@@ -1,13 +1,22 @@
 # SOUND
 
-> SOUND freq, dur_ms [, vol] [BG]
+> SOUND freq, dur [, vol] [BG]
 
-Plays a sound.
+Plays a sound with the frequency `freg` in Hz for a duration `dur` in milliseconds. The optional parameter `vol` controls the volume of the sound. Volume is in the range from 0 to 100, where 100 is maximum volume. If the optional parameter `BG` is given, the sound will play in the background: SmallBASIC will not wait with program execution until the sound has finished.
 
+### Example1 : Play sound
+
+```
+Sound 1000, 800, 50             ' 1000 Hz, 800 ms, 50% volume
+```
+
+### Example 2: Play sound in background
+
+```
+Sound 1000, 800, 50 BG          ' 1000 Hz, 800 ms, 50% volume
+print "This line will be printed immediately"
+pause
+```
 
-* freq The frequency
-* dur_ms The duration in milliseconds
-* vol The volume in 1/100 units
-* BG Play it in background