I just realized in the function LoadSound(), where there is the string "dumpfbacke", assembling HTML <audio> tags, these tags are not closed by a </audio> tag, so please insert that. Edit from:
dumpfbacke=dumpfbacke+"<audio src='"+path+"' preload muted style='position: absolute; top: 10px; left: 330px; display: none'>";
to
dumpfbacke=dumpfbacke+"<audio src='"+path+"' preload muted style='position: absolute; top: 10px; left: 330px; display: none'> </audio>";