What is it?
We talk on the phone; we listen to the presentations and speeches in the concert halls. Some of us try to eavesdrop on other people's conversations, others make a wiretap impossible. However, such situations happened for all the above cases, where background noise prevented to hear somebody’s conversation that words became simply unintelligible. In order to avoid such problems before the operation of sound channels is carried out the acoustic examination of speech communication channels.
Channel or speech communication channel (or voice data transmission channel) – it is the physical environment, the distance that the sound goes from the starting point to ending. It may be the air, electroacoustical, vibrational, parametric, optical-electronic channel, but let us do not consider them, because our goal is measuring the most important quality criterion of sound channel - speech intelligibility.