In the 17th Century, speaking tubes were adapted to a very special sort of hearing problem by Puritan couples who were courting. Custom of the time required the two to sit across a table from each other, and speaking tubes were used to ensure the privacy of their conversations.
Now that's the sixteen hundreds.

http://www.hearingcenteronline.com/museum.shtml

Any bets that it goes back even further.
In addition to that this quote was missed by one of you who had quoted from the same page "Later designs of the voice pipe inserted a removable cork-mounted whistle, which could be sounded by blowing into the tube from the other end." Which is exactly what I was referring to. http://en.wikipedia.org/wiki/Speaking_tube#_note-gower

The Internet is a useful tool but if your desire is to become informed then you have to resist the temptation of cherry picking your information to fit any preconceived notions.
There's nothing personal in this. Just the quest for knowledge.