i loved this
https://earth.google.com/earth/d/1P4c1LpgOiJB9qvJfLlA9yswjLQMdLj14?usp=sharing
Receiver-in-canal and receiver-in-the-ear designs both have a behind-the-ear part that attaches to a receiver in the ear or ear canal with a tiny cord. These enable low-frequency seems to enter the ear naturally