speaking tube vs tubing

speaking tube and tubing both are nouns.

Word	Noun	Adjective	Verb	Adverb
speaking tube	Yes	No	No	No
tubing	Yes	No	No	No

As nouns, tubing is a hypernym of speaking tube; that is, tubing is a word with a broader meaning than speaking tube:

speaking tube: a tube for conveying the sound of a voice from one room to another
tubing: conduit consisting of a long hollow object (usually cylindrical) used to hold and conduct objects or liquids or gases

Other hypernyms of speaking tube include tube.

speaking tube (noun)	tubing (noun)
a tube for conveying the sound of a voice from one room to another	conduit consisting of a long hollow object (usually cylindrical) used to hold and conduct objects or liquids or gases