Yes, I read on exploding head syndrome as well...another name, I guess?

What you're describing sounds like auditory sleep starts. I get most auditory, and at times a combination of visual and auditory. I jump in a very startled state.

Here's some stuff. There's alot when you google either auditory or visual sleep starts...

Everyone experiences, at some time or another the sensory sleep start which is the body jerking, feeling like falling, etc. This is along the same lines to my understanding. When I do it, it's very yuck because I do it several times in one night then for many nights in a row.

Also known as sleep starts, hypnagogic jerk or predormital myoclonus, hypnic jerks usually consist
of a single contraction that often affects the body asymmetrically. They were first described by Mitchell
in 1890 ([7]). The jerk may be either spontaneous or induced by stimuli. Sleep starts are sometimes
associated with the subjective impression of falling, a visual sleep start (sensation of blinding light coming
from inside the eyes or head), an auditory sleep start (sloud snapping noise that seems to come from inside
the head) or a visual hypnagogic dream or hallucination. Pure sensory phenomena in the absence of a
body jerk (so-called "sensory sleep starts") can also occur. The patient may not recall a jerk that was
noted by a bedpartner if the sleep start does not cause awakening. Sleep starts are an essentially universal
component of the sleep-onset process, although they often are not recalled. A prevalence of 60% to 70%
has been reported
1
. Excessive caffeine or other stimulant intake, prior intense physical work or exercise,
and emotional stress can increase the frequency and severity of sleep starts