Lung sounds are the noises a person makes as they breathe in and out, including sounds of regular breathing. However, wheezing, crackling, stridor, and other sounds can also occur, indicating an underlying condition.

An individual’s respiratory system comprises many parts, including:

  • the lungs
  • the airways, such as the trachea and bronchial tubes
  • blood vessels and muscles
  • the ribs
  • the diaphragm

When a person breathes, these parts work together to provide the body with oxygen. During breathing, an individual’s lungs can make a variety of sounds.

While certain lung sounds are typical and indicate that the lungs are working correctly, other sounds can indicate an underlying health condition.

This article will explore the different lung sounds and what may be causing them. It also discusses potential treatment options and when to speak with a doctor.

When a doctor listens to someone’s lungs using a stethoscope, they note the frequency, intensity, and quality of the sounds they hear. These factors can help them determine whether the sounds from the lungs are regular or not.

Breath sounds can differ depending on where they occur in the respiratory system. Healthcare professionals classify them in the following ways:

  • Vesicular breath sound: Vesicular breath sounds predominantly occur when someone breathes in. The sound is soft, low-pitched, and rustling in quality.
  • Bronchial breath sound: The bronchial breath sound is audible over the trachea as a person breathes out. The sound is loud, hollow, and high-pitched. However, if a doctor hears a bronchial breath outside the trachea, it could indicate a health issue.
  • Bronchovesicular sounds: Bronchovesicular breath sounds occur when something breaths in and out. They are mid-range in intensity and pitch and occur in the upper third of the chest.

Wheezing is a high-pitched, musical, continuous sound. A doctor may be able to hear a person wheezing with or without a stethoscope.

Health experts classify wheezes into two groups:

  • Monophonic wheezes: This type of wheeze produces one note and occurs during inhalation or exhalation. A monophonic wheeze can have a constant or varied frequency, and it may have a long duration or occur during both phases of respiration.
  • Polyphonic wheezes: A polyphonic wheeze has multiple notes and occurs during exhalation. They can also increase in pitch toward the end of exhalation.


Wheezing can result from blockages or when something constricts a person’s airways. Causes of wheezing can include:

Crackles, also known as rales, are intermittent sounds generally audible during inhalation. They can sound similar to bubbling, popping, or clicking noises.

Experts may categorize a crackle as:

  • Fine: These occur in the small airways and are soft, short, and high-pitched. Fine crackles only happen during inhalation and may sound like strips of Velcro separating.
  • Coarse: Coarse crackles occur in the larger bronchi tubes and are loud, low-pitched, and last longer than fine crackles. They may sound like ‘popping’ and may resolve after someone coughs.


Crackles occur as a result of small airways suddenly snapping open. They may indicate that a person’s lungs have fluid inside them or are not inflating correctly.

Causes of crackling include:

Rhonchi are low-pitched, continuous sounds that sound similar to snoring. They occur due to blockages in the large airways of the lungs.

Rhonchi can occur during exhalation or exhalation and inhalation, but not inhalation alone.


They happen due to fluid movement and other secretions in the large airways. This can result from conditions such as asthma and viral infections in the upper respiratory system.

Stridor is a high-pitched sound that develops in the upper airway. It mainly occurs when a person inhales and is mostly audible in the neck.

They develop due to an obstruction in the upper respiratory tract. The sound comes from air squeezing past a narrowed area of the upper respiratory tract.


Causes of stridor include:

  • laryngomalacia, where an infant’s larynx tissue is soft and floppy
  • vocal cord lesions
  • inhaled foreign body
  • compression due to swelling or lesions
  • laryngeal cancer

Pleural rub is a creaking, grating, rubbing sound that occurs due to inflamed pleural surfaces rubbing against each other. The pleurae are membranes that cover a person’s lungs and aid respiration.

This sound may be louder than other lung sounds as it occurs closer to the chest wall.


An individual’s pleurae can become inflamed due to certain health conditions that cause pain or tenderness. Causes of pleural rub include:

  • pneumonia
  • pulmonary embolism, a blood clot that travels to an artery in the lungs
  • malignant pleural disease, a buildup of fluid and cancerous cells that gathers between the chest wall and the lungs
  • pleurisy, when the pleurae are inflamed

When a doctor wants to listen to a person’s lungs, they will generally use a stethoscope, which they place on various parts of a person’s chest and back to check for different lung sounds.

They may tap an individual’s back to listen for nodules or fluid buildup. This technique involves placing the stethoscope below a person’s rib cage and tapping down their back to listen for changes in pitch when tapping.

They may also use other listening tools, such as computerized lung sound analysis devices, for diagnosis. Doctors can also request blood tests, CT scans, or X-rays during diagnosis.

The treatment for atypical lung sounds will depend on the cause and severity of their symptoms.

An individual with irregular lung sounds may require antibiotics if there is an infection. Doctors may also recommend anti-inflammatories to treat conditions involving inflammation.

A person with a long-term lung condition may require regular medications or treatments.

If there are more serious symptoms, treatment in the hospital and possibly surgery may be necessary.

Healthcare professionals typically hear unusual or atypical lung sounds using instruments like a stethoscope. People may not be able to hear these sounds with the naked ear.

However, the various causes of lung sounds may also lead to other symptoms. Anyone who notices new symptoms related to their breathing should speak with a doctor for a diagnosis. These symptoms could include:

If someone has difficulty breathing, they should seek immediate medical help.

Certain lung sounds may indicate a person has an underlying health condition, such as pneumonia, COPD, or a respiratory infection.

If an individual notices any unusual lung sounds or symptoms, they should speak with a doctor. Their doctor can listen to the sounds with a stethoscope and carry out a complete diagnosis.

Seek urgent medical attention if a person has difficulty breathing or stops breathing.