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. 2023 Jun 12;23(12):5514. doi: 10.3390/s23125514

Table 2.

Abnormal Lung sounds.

S. No. Location Mechanism of Production Characteristics Acoustics Associated Pathological Conditions
1. Stridor [31] Proximal/upper airway Airway obstruction/narrowing

  • High-pitched

  • Inspiratory (supraglottic narrowing/obstruction)

  • Biphasic (glottis/subglottis/cervical trachea)

  • Expiratory (thoracic trachea/bronchi)

 >500 Hz

  • Adenoid hypertrophy, craniofacial abnormalities, choanal atresia, etc. (inspiratory)

  • Laryngomalacia, vocal cord palsy, laryngeal mass, etc. (biphasic)

  • Tracheal stenosis, foreign body, vascular compression, etc. (expiratory)
2. Wheeze [32] Anterior/posterior chest wall Airway narrowing (spasm/mass/mucus plugs/foreign body/parasite infestation)

  • High-pitched

  • Shrill, coarse whistling/rustling

  • Intensity on expiration > inspiration

 100–5000 Hz

  • Asthma

  • COPD

  • Endobronchial mass

  • Mucus plugging

  • Foreign body
3. Rhonchus Anterior/posterior chest wall Passage of air through lower respiratory tract secretions

  • Low-pitched, squeaky

  • Intensity on expiration > inspiration

  • Character affected by coughing

 ~150 Hz

  • Pneumonia

  • Chronic bronchitis

  • Bronchiectasis
4. Coarse crackles [33] Anterior/posterior chest wall Passage and opening of airways clogged by secretions and fluids

  • Low-pitched

  • Biphasic beginning at early inspiration

 ~350 Hz

  • Pulmonary edema

  • Pneumonia

  • Bronchiectasis
5. Fine crackles [33] Anterior/posterior chest wall Opening of collapsed terminal airways

  • High-pitched

 ~650 Hz

  • Interstitial lung diseases

  • Congestive heart failure

  • Pneumonia