Understanding different Types of Breathing Sounds

If you have ever been to a doctor’s clinic, then chances are high that you have experienced the doctor moving his stethoscope around your chest and back area while concentrating hard to find out if something is wrong with you. This procedure is referred to as “Auscultation”. 

Auscultation helps in finding out if there is anything wrong with your lungs and airways because any abnormal breathing sounds can be easily heard through a stethoscope. A person who is normal and healthy typically breathes without making any audible noise. (You may stop for 1 minute and hear yourself breathe. Nothing? That means you are breathing normally.)

However, not every abnormal breath sound is to be heard by the person experiencing it. These sounds or noises are barely audible unless otherwise heard over a stethoscope but sometimes healthy breath sounds can be audible too. So, what are these abnormal breath sounds and where do they come from? Let us find more about them. 

What are Abnormal Breath Sounds?

Normally, the airflow through the respiratory tree is laminar (streamlined) and encounters no obstruction. Thus, with each breath taken in and out, a gush of air moves through the respiratory tree without producing any sound.

 When there is an underlying disease process such as inflammation, obstruction, infection, or the presence of fluid in the lungs, the airflow get turbulent and abnormal breath sounds are produced as a result.These sounds may or may not be heard by the person having the disease, requiring auscultation and other specialized tests can help in making a diagnosis. 

Causes of Abnormal Breath Sounds 

Any pathology that interferes with the normal airways and their functions is said to give rise to abnormal breath sounds. Some common causes include:

  • Pneumonia 
  • Chronic Obstructive Pulmonary Disease (COPD)
  • Presence of Foreign Body in the Airways
  • Heart Failure-Related Issues
  • Bronchitis

Each one of the above mentioned causes gives rise to a different, characteristic abnormal breathing sound.

Types of Abnormal Breath Sounds

Here, we have enlisted some of the common abnormal breath sounds that are most commonly heard with a stethoscope and then treated accordingly by the doctor. 


Previously recognized by the name of “Rales”,  these abnormal breathing sounds are discontinuous types of sounds that are heard when a person inspires air. They resemble crackling, rattling or light bubbling type sounds, and are slow, high-pitched sounds. Depending on the underlying condition, the crackles might be classified as coarse or fine-quality crackles.

Indication: Crackles indicate the presence of fluid (such as pus or mucus) in the lungs, and may be associated with pulmonary edema, asthma, bronchitis, and congestive heart failure. 


Now more prominently known as “Sonorous Wheezes”, the rhonchi are continuous, low-pitched sounds that are heard on both, inspiration and expiration of air.
They are named so because they closely appear to be like snoring and gurgling sounds. If a person coughs, then these rhonchi can be cleared over for some time too.

Indication: These sounds indicate blockage of the airways due to any secretions or foreign bodies, etc. 


Wheezes and rales are terms that are often used interchangeably. There are minor differences that differentiate between the two. Wheezes are also referred to as “Sibilant Wheezes”.
These are continuous, high-pitched, almost shrill sounds that are typically heard during expiration.
They are the characteristic sounds heard in an asthmatic patient.

Indication: These sounds indicate the narrowing or constriction of the airways and point towards conditions like asthma, chronic bronchitis, etc. 


Stridor is a continuous, high-pitched sound that is found on either inspiration or expiration but most commonly occurs during inspiration. It is more of a “crowing” sound and points towards a condition that requires immediate attention and treatment.

Indication: Whenever present, stridor points out towards a serious, potentially life-threatening condition. It indicates that the larger airways, that is, either the trachea or the main bronchus have been obstructed and need to be immediately looked upon.
When present in children, it points towards the croup. In adults, it may occur due to a foreign body obstruction, laryngeal edema, epiglottitis, etc.

Pleural Friction Rub

A pleural friction rub is caused due to the inflammation of the linings of the lungs, the parietal and the visceral pleura. These linings stick together and cause a grating sound. It is a painful condition.

Indications: Pleural effusion, Pneumothorax.

Based on the type of abnormal breathing sound present, several investigations may be carried out to rule out the diagnosis. These investigations include:

  • Pulmonary Function Tests (PFTs)
  • Chest X-ray 
  • Chest CT Scan
  • Sputum Culture, etc. to name a few.

Based on the type of condition causing the abnormal breathing sound, a doctor may suggest antibiotics if there is a persistent infection, there might be even an advised hospital stay for people whose condition is deteriorating because of poor breathing rates, and breathing exercises may be advised to people with mild to moderate disturbances in breathing.


  1. Sarkar M, Madabhavi I, Niranjan N, Dogra M. Auscultation of the respiratory system. Ann Thorac Med. 2015;10(3):158-168. doi:10.4103/1817-1737.160831
  2. Zimmerman B, Williams D. Lung Sounds. [Updated 2019 Sep 27]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2020 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK537253/

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