7.1 surround sound - Wikipedia

Phone connector (audio) - Wikipedia

What is a 7.1 surround sound system? - Quora

Digital room correction - Wikipedia

Stereophonic sound - Wikipedia

Top 6 Wireless Surround Sound Systems

Dolby Surround 7.1, Dolby Wiki

American Broadcasting Company - Wikipedia

5.1 Surround Sound - Wikipedia, PDF, Sound Production Technology

Surround Sound - JRiverWiki

THX - Wikipedia