So if a sound causes the vocal cords to vibrate, they are
voiced? And when they aren't vibrating, they are voiceless?
Exactly, although I might not characterize the sound as
"causing" the vocal cords to vibrate. Think of a sound as an
abstract unit: it may have the feature of voicing (like [z]) or
it may not (like [s]). So Aspiration is the sound between a stop
consonant, right...? Here's a simpler way to think about
aspiration: put a piece of paper in front of your mouth and say
the words "pit" and "spit". For "pit", there should technically
be a "puff" of air that makes the paper rustle, although the
force can vary between speakers. In contrast, there shouldn't be
any puff of air in "spit". This is because the [p] in "pit" is
aspirated (a common feature of "stops" at the beginning of a
syllable in English), while the [p] in "spit" is unaspirated (a
common feature for "stops" when they appear in a consonant
cluster, like "sp-"). As Linguoboy noted, the main technical
(phonetic) aspect of aspiration is that i