話頭 is read as わとう (watou) and means topic.
わとう
watou
はなしあい
discussion
はなしこむ
to be deep in talk
はなしあう
to discuss
はなしことば
spoken language
はなしごえ
speaking voice
はなしあいて
person with whom to speak
わじゅつ
art of conversation
はなしがあう
to see eye to eye
はなしあいがつく
to come to an agreement
わだいか
topicalization
わほう
narration
わだいせい
newsworthiness