Um... an audience?
A group of spectators are called an audience.
spectators
In the phrase, "a group of spectators", the noun "group" is functioning as a collective noun. The standard collective noun is "an audience of spectators"; however, collective nouns are an informal part of language. Any noun that suits the situation can function as a collective noun.
audience
audience
The collective noun is called a gaggle. Also spectators
No. It's just the plural form of a singular noun. If you said 'a group of spectators' the word group would be a collective noun.
A group of onlookers are called a faculty
Male spectators in the 15/95 age group.
they are called the gallery
they are the gallery
An assembly of listeners or an assembly of spectators is use of the collective noun, assembly.