Manual

31
IX. Why do I Hear Hear Myself Myself?
Mix-Minus and Eliminating echo
Studio telephone integration is a two-way process. The caller must send his audio to the studio, but also
receive a return feed that allows him to interact with other sources, like a host. An important element of
voice telephony involves allowing a speaking party to hear his own voice in his own earpiece. This sidetone
provides a speaker the comfort of knowing his voice is getting through, and makes two-way communication
flow more easily.
But for several reasons, telephone sidetone is always generated locally within the speaker’s equipment,
rather than on the far end of the call. This is because humans have a very hard time handling even the
smallest delay in this sidetone signal. In testing, we find that any delay over around 10mS starts to have an
effect called “slapback” where the speaker is unable to maintain conversation and begins to halt and stutter.