Dr Sound explains double talk

Dear readers, Dr Sound is back with a new post about sound and sound technology. The subject this time is a really exciting and interesting one called double talk.

Double talk … or full duplex, is all about having the capability for several people being able to talk at the same time, without anyone being cut out. The simplest form of remote communication is what we call simplex. With simplex, one device transmits while the other receives, and only one device can transmit at a time.

Full Duplex means that people can talk at the same time without anyone being cut out.

This is how a traditional communication radio work, with a button you push when you talk. We've all seen movie heroes, with their helmets askew, shouting into a communication radio things like: "We need support, over! We'll cover you! Over and out!"

Simplex, only one device can transmit while the other receives Like a traditional communication radio.

The intermediate step is half duplex. It's like simplex but is automatically controlled, with the direction of communication being determined by who speaks the loudest. Before the digital era, and consequently before echo cancellation, full duplex was impossible for a speaker phone simply because it would have caused feedback. The incoming “speaker sound”, along with the effects of the room, could not be eliminated before the microphone transmitted.
This is why full duplex is the aim for all telecommunication and also during teleconferences. Long distance conversations with full duplex, are now possible thanks to good digital technology and echo cancelling. A fact that has given us the capability to interrupt one another…