While talking, there are rises and falls in our voices. It means that our voices go up ( ➚  ) and down ( ➘  ) frequently.
When we ask yes/no questions or questions made by auxiliary verbs, our voice rise.
When we ask questions with What, Who, Which, When, Why or How, our voices fall.
In statement, our voice falls too.
For example:

How old are you? ( ➘  )

Who is that man? ( ➘  )