Breath Sounds pp 181-206 | Cite as

Normal Versus Adventitious Respiratory Sounds

  • Alda Marques
  • Ana Oliveira


Respiratory sounds are composed by normal and adventitious respiratory sounds which comprise the sounds heard over the trachea/mouth and chest wall. All sounds can be described using frequency, intensity, and timbre. Frequency and intensity are perceived by human beings as pitch and loudness, respectively. Timbre allows the differentiation between two sounds with the same frequency and intensity. For respiratory sounds, some additional information is often informative, such as the timing within the respiratory cycle in which the sound occurs, the sound duration, and the influence of gravity/forced expiratory maneuvers on the sound. It is also important to know the origin and mechanisms of the respiratory sound. Normal and adventitious respiratory sounds can be highly informative about a person’s respiratory health as it is known that their characteristics change with gender, location where it is heard, body size, body position, and airflow, being particularly different between children and adults and in the presence of a respiratory condition. This chapter provides a comprehensive understanding of the use of normal and adventitious respiratory sounds for identifying respiratory conditions and their severity and monitoring respiratory interventions.


Normal tracheal sound Normal lung sound Crackles Wheezes 


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© Springer International Publishing AG, part of Springer Nature 2018

Authors and Affiliations

  1. 1.Lab 3R—Respiratory Research and Rehabilitation Laboratory, School of Health SciencesUniversity of Aveiro (ESSUA)AveiroPortugal
  2. 2.Institute for Research in Biomedicine (iBiMED)University of AveiroAveiroPortugal

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