Respiratory sounds

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Respiratory sounds
ICD-10 R06
ICD-9 786.7
MedlinePlus 007535
MeSH D012135

Respiratory sounds, breath sounds, or lung sounds refer to the specific sounds generated by the movement of air through the respiratory system. These may be easily audible or identified through auscultation of the respiratory system through the lung fields[1] with a stethoscope. These include normal breath sounds and adventitious or "added" sounds such as rales, wheezes, pleural friction rubs, stertor and stridor.

Description and classification of the sounds usually involves auscultation of the inspiratory and expiratory phases of the breath cycle, noting both the pitch (typically described as low, medium or high) and intensity (soft, medium, loud or very loud) of the sounds heard.

Types of normal breath sounds[edit]

Vesicular - heard over most of the lungs. Often described as similar to a soft rustle (of leaves). The inspiratory sounds are faster and louder and longer than expiratory sounds. The expiratory intensity is soft, the pitch is low, and the sound dies away after the first third of the expiratory phase.

Bronchovesicular - heard over the 1st and 2nd intercostal spaces and the interscapular area. The inspiratory and expiratory phases are roughly equal in length.

Bronchial - may be normally heard over the manubrium. Expiratory phase is greater than inspiratory. The expiratory pitch is high and intensity is loud.

Tracheal - heard directly over the trachea. Inspiratory phase equals the expiratory phase. The sound is very loud and the pitch very high.

Types of adventitious breath sounds[edit]

Common types of abnormal breath sounds include the following:[2]

Name Continuous/discontinuous Frequency/Pitch Inspiratory/expiratory Quality Associated conditions Example
Wheeze or rhonchi continuous high (wheeze) or lower (rhonchi) expiratory or inspiratory whistling/sibilant, musical Caused by narrowing of airways, such as in asthma, chronic obstructive pulmonary disease, foreign body.
The sound of wheezing as heard with a stethoscope.

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Stridor continuous high either, mostly inspiratory whistling/sibilant, musical epiglottitis, foreign body, laryngeal oedema, croup
Inspiratory and expiratory stridor in a 13-month child with croup.

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Inspiratory gasp continuous high inspiratory whoop pertussis (whooping cough) not available
Crackles (aka crepitations or rales) discontinuous high (fine) or low (coarse), nonmusical inspiratory cracking/clicking/rattling pneumonia, congestive heart failure
Crackles heard in the lungs of a person with pneumonia using a stethoscope.

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Pleural friction rub continuous low inspiratory and expiratory nonmusical, many repeated rhythmic sounds inflammation of lung linings, lung tumors not available
Hamman's sign (or Mediastinal crunch) discontinuous neither (heartbeat) crunching, rasping pneumomediastinum, pneumopericardium not available

Other tests of auscultation[edit]

Pectoriloquy, egophony and bronchophony are tests of auscultation. For example, in whispered pectoriloquy the person being examined whispers - typically a two syllable number as the clinician listens over the lung fields. The whisper is not normally heard over the lungs, but if heard may be indicative of pulmonary consolidation in that area. This is because sound travels differently through denser (fluid or solid) media than the air that should normally be predominant in lung tissue. In egophony, the person being examined continually speaks the English long-sound "E". The lungs are usually air filled, but if there is an abnormal solid component due to infection, fluid, or tumor, the higher frequencies of the "E" sound will be diminished. This changes the sound produced, from a long "E" sound to a long "A" sound.


  1. ^ Respiratory sounds at the US National Library of Medicine Medical Subject Headings (MeSH)
  2. ^ Bohadana, Abraham (February 20, 2014). "Fundamentals of Lung Auscultation". New England Journal of Medicine. doi:10.1056/NEJMra1302901. PMID 24849095. Retrieved February 28, 2015. 

External links[edit]