Wh-question Pitch Boundaries
Introduction to wh-questions
A wh-question begins with the words who, what, why, when, where, and how. These types of questions seek information and cannot be answered with "yes" or "no." Wh-questions can end with a rising or falling pitch boundary, depending on whether the speaker is truly asking a question, or is masking a suggestion as a question.
Rising pitch boundary in wh-question
When the speaker holds no assumption as to what the answer will be, and the topic is new, the wh-question is likely to have a rising pitch boundary.
The rising pitch of this question tells the listener that this is a true question (the speaker does not have any idea of what the answer may be) of a new topic to the conversation.
Falling pitch boundary in wh-question
If a question is asked while a conversation is in progress, the pitch boundary is more likely to fall.
The first question is a yes/no question and uses a rising pitch boundary. The second speaker responds with a new question regarding the game. Since the topic is already in progress, the wh-question uses a falling intonation.
It isn't uncommon for a wh-question to actually be a suggestion, and not be intended as a question at all.
By using a falling pitch boundary, the speaker is essentially saying, "You should ask her out." The speaker is not truly asking why the listener doesn't ask someone out on a date.
To sum up:
Wh-questions can end with a rising or falling pitch boundary, depending on whether the speaker is truly asking a question, or is masking a suggestion as a question.