It's not until after she dies that Scout and Jem get a sense of what's going on behind the drool and venom: Mrs. Dubose is a morphine addict who had vowed to go clean before she died, and enlisted Jem and Scout (without their knowledge) to keep her off the stuff for longer and longer periods of time.
http://lungsounds.net/rales-lung-sounds/ - Rales lung sounds are small rattling noises heard around the lung. This happens when air exposes closed air spaces. Rales can be shown as wet, dry and coarse.
This breath sound is abnormal if heard over the peripheral lung fields. Bronchial Breath Sound-a harsh, high pitch, low intensity breath sound with expiration longer than inspiration (I<E) (1:2). This sound is normal over the trachea but always considered abnormal if heard over the peripheral lung fields.