Question
Do cicadas sing during the day and crickets at night or do the cicadas simply drown out the lone cricket serenade?  I'm referring to northeastern Oklahoma territory.

Answer
Crickets usually sing both day and night. Cicadas sing day mostly but also at night. Here is a web link to sounds of crickets and cicadas. The Fall Field cricket sound  and the Scissor-grinder cicada seem to  the more representative sounds of crickets and cicadas.

http://www.musicofnature.com/songsofinsects/index.html