I became interested in finding out just when the pitch pipe had been invented and, as we do when we are interested in pretty much anything today in this technology advanced age, I Googled it and came up with the following link that takes you to a site page that contains the written history of the pitch pipe that is used by most barbershoppers today. Click on it and enjoy reading.
http://www.gradywilliamkerr.com/PitchPipes/PitchPipe.html