Siflement or Sifflement: How To spell?
The word Siflement is misspelled against Sifflement, a noun meaning "The act of whistling or hissing; a whistling sound; sibilation."
Sifflement has double "ff" is mispronounced as "f"Remember double 'FF' in between the strings Si & lement which should not be misspelled with single 'F'
Wrong Spelling:  Si-f-lement  Correct Spelling:  Si-ff-lement 
Find more wrongly spelled words of Sifflement to spell it well.