Auscultation of Adventitious Breath Sounds

Abnormal breath sounds are called “extra” or “adventitious” breath sounds. Adventitious breath sounds include crackles (formerly known as rales), wheezes, rhonchi and friction rubs.

Breath Sounds

Breath Sounds

Air flowing by liquid cause crackles (rales).

  • Crackles can be fine, medium or coarse.
  • Fine crackles are high-pitched crackling or popping sound.
  • Coarse crackles are a low-pitched gurgling sound.
  • These sounds are usually heard during inspiration.
  • Crackles create a dry sound when heard higher in the bronchial tree.
  • Crackles create a wet sound when heard lower in the bronchial tree.

Air flowing through constricted airways cause wheezes.

  • Wheezes have a high-pitched musical sound.
  • High-pitched wheezes are sibilant.
  • Low-pitched wheezes are sonorous.
  • Heard on inspiration and expiration.
  • Wheezes are continuous.
  • They are unusually bilateral. Wheezes that are unilateral are usually due to an obstruction by a foreign object.

Air flowing over thick secretions cause rhonchi.

  • Rhonchi create a low-pitched sound.
  • They are usually continuous and prolonged.
  • Sibilant or high pitched rhonchi are heard over the smaller bronchi.
  • And, sonorous or low pitched rhonchi are heard over the larger bronchi.
  • It is sometimes hard to distinguish between crackles and rhonchi. Therefore, have the patient cough. If it disappears, it is usually rhonchi.


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