Here’s an interesting blog article on hemiolas with explanation and examples. This is part 2 of his article because I very much liked the example of a line from Rodgers & Hammerstein’s song “My Favorite Things.”
Have a listen. My underlying drum beat starts and stays in 3/4 time. The only thing I’ve done to emphasise the hemiola is to accent every other beat during it as if it were in 2/4 time. After you’ve listened to it once or twice try counting 1, 2, 3, 1, 2, 3 through the whole thing.
[audio:https://www.lewesvoiceworks.org/wp-content/uploads/2012/02/My-Favourite-Things-example.mp3|titles=My Favourite Things example]