What is the meaning of "bucket on the head" in this context?
Patulous Eustachian tube […] is a physical disorder where the Eustachian
tube, which is normally closed, instead stays intermittently open.
When this occurs, the patient experiences autophony, the hearing of
self-generated sounds. These sounds, such as one's own breathing,
voice, and heartbeat, vibrate directly onto the ear drum and can
create a "bucket on the head" effect.
(Source)
Best Answer
Firstly, "Bucket on the head" is not an idiom or an expression used in English. I think the phrase "Bucket on the head" is used literally here. What happens when you put your head in a bucket and stand still? You can hear yourself breathe. The echoes of your respiration will be caught by your ear drums. You can hear every 'sigh' and 'gulp', in a magnified intensity. These are things you generally don't hear (or notice). But when your head is in a bucket, the closure of the bucket helps you hear every single breath, every heartbeat.
Since the context talks about the same things I've mentioned, I don't think "bucket on the head" has any other meaning here.