Lung sounds are the noises a person makes as they breathe in and out. These sounds include regular breathing, but wheezing, crackling, stridor, and other sounds can also occur.

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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. And while certain lung sounds are typical and indicate that the lungs are working correctly, other lung 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 a person’s lungs, 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:

  • Normal lung or vesicular breath sound: A doctor can hear this sound over most of the chest with a stethoscope, a device for listening to a person’s internal body sounds. Vesicular breath sounds occur when air flows into and out of the lungs during breathing. The sound is soft, low pitched, and rustling in quality. It is also continuous, more intense, and high pitched during inhalation than exhalation.
  • 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.
  • Normal tracheal breath sound: A doctor can hear this sound over the trachea. It is very loud, harsh, and high pitched.

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

Health experts classify wheezes into three 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 towards the end of exhalation.
  • Squawks: A squawk is a brief wheeze that occurs during inhalation.

Wheezing can result from blockages or when a person’s airways become constricted. 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 define a crackle as:

  • Fine: These occur in the small airways and are soft and high pitched. Fine crackles may occur more frequently during a breath than coarse crackles and only happen during inhalation.
  • Medium: These result from air bubbling through mucus in the small bronchi — two tubes that carry air from the trachea to the lungs. The bronchi branch off into smaller and smaller passageways, which eventually lead to air sacs called alveoli.
  • Coarse: Coarse crackles occur in the larger bronchi tubes and are loud, low pitched, and last longer than fine crackles. They mainly occur during inhalation but can also happen during exhalation.

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 the movement of fluid 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 can mostly be 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
  • tracheomalacia, a condition that causes the cartilage of an infant’s trachea to be weakened and soft
  • bronchomalacia, a condition where an infant has weakened cartilage in their bronchial tubes
  • compression due to swelling or lesions

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.

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 become 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 also 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. This helps the healthcare professional listen for any 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.

Anyone who experiences unusual or atypical lung sounds should speak with a doctor. Certain lung sounds can indicate serious health conditions.

While lung sounds are usually typical, some may indicate a person has an underlying health condition.

If an individual notices any unusual lung sounds, they should speak with a doctor. There are various methods that healthcare professionals can use to determine why irregular lung sounds occur.

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