Your hands should be about ear height, and your elbow should be bent around 90 degrees. (marksdailyapple.com)
As a parent, doula, educator and lactation support person, I hear and see new parents regularly with their shoulders hovering somewhere around ear height. (mommysbliss.com)
The center channel should be as close to ear height as your setup allows and can be placed either above or below the screen. (howtogeek.com)