Seth, 

No, as an isolated spoken phrase you cannot ‘hear’ whether it is plural or singular. They are pronounced identically. 

However the preceding ‘ il y a des artistes …’  gives a very strong clue. 

It is unlikely (not impossible) that the artists have only one creation between them, or that each artiste has only one creation, either of which would have the phrase in the singular, but very likely that each artiste would have multiple creations on display. ( If the situation was otherwise, further description of the situation would be expected).  Multiple possessions owned by ‘them’ gives the 3rd person plural expression you reference.

See the 2 links below, ( and note ‘the really tricky part’ section Laura Lawless highlights, where ambiguity can persist).

 Notre/nos/votre/vos/leur/leurs = our/your/their (French Possessive Adjectives)

 https://www.lawlessfrench.com/grammar/possessive-adjectives-plural-possessions/