The Latin verb crepitare has given us several interesting words, most of them used in a medical context. In that language, crepitare meant to crackle.
So, a crepitant sound is a rattling or crackling, something that will be heard in the lungs of a pneumonia patient, or the sound produced by joints or broken ends of bones rubbing together.
Crepitation is the noun form signifying a crackling noise, and to crepitate is the verb form.
Decrepit means worn out from old age, illness, or hard use, and decrepitude is the noun signifying that state or condition. Figuratively, things have cracked open.
To decrepitate is to subject crystals or salts to high heat so that they crackle and disintegrate.
Finally, a crepitaculum is the name herpetologists use for the rattler of the rattlesnake.
SIDEBAR: listen to crackles
SIDEBAR: rattlesnake sounds:
(substitute @ for AT above)