Swiss sound (5)
I believe the answer is:
yodel
'swiss sound' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for yodel that I've seen before include "Sing (in the Alps)" , "Sing using falsetto" , "Sing in high pitch like Swiss mountain dwellers" , "Sing (Alpine folk music)" , "unusual singing" .)