A sigh is an expression that comes from the heart.
If it's expressed downwards, it becomes something else.

An interesting thread...Should be dedicated to Joseph Pujol who lived and worked in France in the last quarter of the 19th c. He performed at the Moulin Rouge, at one point, and gave private audience to Prince Albert (much to queen Victorias disgust) He was known as "Le Petomane" or translated "The farter". He could imitate machine gun fire and artillery fire...could fart the Marsellaise and many other tunes, making himself a small fortune in the process.
A film was made of his exploits and starred Leonard Rossiter as "Le Petomane"...If you can get hold of the film, please do watch it ....it is so funny.
Be Blessed