Breath Sounds pp 225-236 | Cite as

Crackles and Other Lung Sounds

  • Konstantinos Douros
  • Vasilis Grammeniatis
  • Ioanna Loukou


Crackles are intermittent, nonmusical, and brief adventitious lung sounds that can be heard on inspiration and sometimes during expiration. They are classified as fine or coarse depending on their frequency and duration; fine crackles have high frequency and short duration, whereas coarse crackles have lower frequency and longer duration. They are generated when air is forced through abnormally narrowed respiratory passages. The study of lung sounds, in general, and crackles, in particular, has advanced rapidly in the last two decades, thanks to the contribution of evolving technology. Based on various methods of artificial intelligence, researchers have managed to effectively detect and analyze lung sound signals and characterize them objectively. Unfortunately, the diagnostic utility of these high-end methods in clinical settings is still limited. In this review we attempt to summarize what is known about crackles and, in addition, discuss in less detail some of the other less common adventitious lung sounds.


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Suggested Sites with Recordings of Lung Sounds

  1. European Respiratory Society - Reference Database of Respiratory Sounds
  2. The R.A.L.E.® Repository –

Copyright information

© Springer International Publishing AG, part of Springer Nature 2018

Authors and Affiliations

  • Konstantinos Douros
    • 1
  • Vasilis Grammeniatis
    • 1
  • Ioanna Loukou
    • 2
  1. 1.Pediatric Allergy and Respiratory Unit, Third Department of Pediatrics, “Attikon” HospitalUniversity of Athens School of MedicineAthensGreece
  2. 2.Cystic Fibrosis Unit“Aghia Sophia” Children’s HospitalAthensGreece

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