Doesn’t the ‘nel’ in tunnel break this?
Really? I think it’s supposed to be silent, not a schwa. Did you mean “tuh-nl”?
Slow down your speech a bit (like listen to it in super slow mo) and you’ll realize there’s definitely a schwa sound between the N and the L sounds. Just how our mouths work moving through the shapes for them creates a schwa sound.
Tangentially related to getting stuck in a tunnel obstructed by onions: one time I was stuck in a traffic jam on I-95 in Philadelphia, traffic completely stopped for about three hours. Eventually we got moving again and passed the source of the jam. A semi carrying a load of honeydew melons had caught fire. I would have thought melons contained enough water to prevent them from burning, but that was not the case.