When was an "international" standard for precise pitch finally established?

Which jazz trombonist also used conch shells to create what was known as "open source" improvised music?

a) Steve Coleman b) J.J. Johnson c) Steve Turre d) PaquitoD'Rivera

The person who operates the video switcher is normally called the:

a. director. b. switching assistant. c. operational director. d. switcher.