Adventitious Sounds

Adventitious sounds

1. Crepitations
2. Rhonchi
3. Pleural rub



Crepitations are discontinuous (<20 millisecond in duration) bubbling or crackling sound produced by the passage of air through exudate-filled bronchi, bronchioles, alveoli, big cavity, or due to sudden snapping open of the relatively stiff alveoli at inspiration.

Fine crepitations (end – inspiratory) – 

soft, high-pitched and <10 ms in duration, and is produced due to the presence of exudates in the alveoli.
LVF (at lung bases)  crepitations are often silenced by bending forward.
Fibrosis of the lung
Indux crepitations of pneumonia ( i.e., early stage of consolidation)
Fibrosing alveolitis ( velcro crepitations – sound resembles as if two strips of adhered velcro tapes are being separated. ) → crepitations are due to sudden snapping open of the relatively stiff alveoli at the end of inspiration & are uninfluenced by coughing.

Coarse crepitations ( biphasic – both inspiratory & expiratory)-

 louder, low-pitched and < 20 ms in duration, and is produced due to the presence of exudates in the bronchi, bronchioles, alveoli or big cavities.
Acute bronchopneumonia
Lung abscess or pulmonary cavity
Redux crepitations of pneumonia (i.e., resolution stage of consolidation)
Cystic diseases of lung
Pulmonary oedema (often called  ‘death rattle’ when occurs as a terminal event).

Types of crepitations in relation to phases of respiration:

A. Inspiratory –
Early – chronic bronchitis
Mid – pulmonary oedema
Late – fibrosing alveolitis, pulmonary oedema, lung abscess, the cavity within the lung.
B. Expiratory –
Severe airway obstruction e.g., bronchial asthma
Post-tussive crepitations – these are the crepitations heard after coughing and are often diagnostic of the superficial tuberculous cavity.


Rhonchi are continuous (> 80 ms in duration), an uninterrupted musical sound produced in the narrowed bronchi or bronchioles as a result of muscle spasm, the collection of viscid secretion, mucosal oedema or narrowing by an endobronchial growth.

Common causes –

Bronchial asthma, COPD
Wheezy bronchitis
Cardiac asthma (LVF)
Tropical pulmonary eosinophilia
Laryngeal oedema

Classification of rhonchi –

A. Monophonic rhonchi – produced due to narrowing of a single bronchus by the tumour or foreign body (i.e., localised obstruction), which produces a single musical note.
B. Polyphonic rhonchi  ( most common type ) – particularly heard in expiration and are characteristically found in diffuse airflow obstruction e.g., bronchial asthma or chronic bronchitis.

Pleural rub

It is a leathery or creaking sound produced by the rubbing of inflamed and roughened, visceral and parietal pleura

The pleural rub is –

Superficial ( the sound seems to be very close to the ear )
Localised – generally heard over the anteroinferior part of the lateral chest wall or in the lower part of the back as the movement of the lung is maximum in these regions.
Disappears when the breath is held.
Intensified on pressing the stethoscope
Neither any alteration after coughing nor any variation with the change of posture.


          High pitched musical sound heard from a distance
    Low – pitched crowing or croaking sound heard from a distance
2.       Better heard in expiratory phase
    Better heard in inspiratory phase
          Indicates small airways obstruction
    Indicates larger airways (larynx, trachea and major bronchus) obstruction
4       Usually associated with rhonchi in the chest
    Very common in children
         Clinical association:
    Bronchial asthma
    Chronic bronchitis
    Tropical eosinophilia
    Cardiac asthma
    GERD with aspiration
    Clinical association:
    Foreign body inhalation in larynx or trachea
    Laryngeal oedema
    Acute epiglottitis
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