In the early days of the telephone, the problem of speaking level was widely noted and discussed. The technological innovation was clever: a small amount of a person’s voice was fed back to the earpiece, and people then naturally adjusted the loudness of their spoken voice to produce a comfortable level of feedback in the earpiece. Numerous studies in auditory psychophysics were performed to determine the correct amount of this feedback — sidetone was the technical term. With the advent of the mobile telephone, sidetone has disappeared, and with it, the so-necessary feedback required to maintain voice level.
Why was sidetone eliminated from mobile phones? Two possible answers come to mind, and my suspicion is that both are correct. One is that modern telephonic engineers have no sense of history, and so they lack all the experience and knowledge that led to the early development of sidetone feedback. The second answer is that sidetone poses more difficult problems in the out-of-doors environment of the mobile phone, where wind noise on the microphone and relatively high-levels of ambient noise pose technical limitations on sidetone. –Don Norman –Minimizing the Annoyance of the Mobile Phone (JND.org)
I was recently lined up in the boarding tunnel at the airport. A woman behind me called up her local library to try to renew a book. She put her portable phone on speaker mode, and kept the librarian on the line while she rummaged through her carry-ons looking for the book.
It was the most annoying telephone experience I’ve had.
When the librarian finally said, “No, I can’t renew your book,” the feeling of satisfaction in the tunnel was palpable. I would have sworn I heard scattered applause.