Multichannel speaker designations follow a full-range plus sub count convention

Evidence

In recent years, additional speakers have been added to 5.1 surround systems. These systems are often designated 7.1, 9.1, 11.2 and so on to designate the extra speakers. The first digit specifies the number of full-range speakers actually used. Thus a 7.1 system would have two additional speakers compared to a 5.1 system, a 9.1 system four additional full-range speakers and so on. The figure after the decimal point denotes the number of low-frequency speakers used. So 7.1 would describe a system with 7 full-range speakers and 1 low-frequency speaker, whereas an 11.2 describes a system with 11 full-range speakers and 2 low-frequency speakers. — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 2226

Categorization

• DEFINE: Decodes the X.Y speaker system naming convention clearly.