Adventitious breath sounds are abnormal sounds resulting from unusual airflow through the lungs. They can be due to conditions, such as asthma or bronchitis.

Anything that changes the normal airflow through the lungs can cause a range of clicks, crackles, wheezes, and snoring noises that doctors classify as adventitious breath sounds.

Individuals may notice these noises themselves or a doctor may discover them when listening to someone’s chest with a stethoscope.

People may experience adventitious breath sounds, also known as adventitious lung sounds, if they have:

Other nonclinical issues can cause unusual breath sounds, such as foreign bodies.

Although adventitious breath sounds may worry someone because they are unusual, they do not necessarily indicate a severe health condition.

In this article, we examine adventitious breath sounds and the different types. We also look at the range of health conditions that can cause these sounds, and when an individual should seek medical attention.

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Adventitious sounds are the medical term for respiratory noises beyond that of normal breath sounds. The sounds may occur continuously or intermittently and can include crackles, rhonchi, and wheezes.

Individuals may notice the abnormal breath sounds themselves, or a doctor may note them while examining the lungs with a stethoscope.

The sounds can be the first symptom of a respiratory illness such as pneumonia.

The types of adventitious breath sound include:


Crackles are slight bubbling, clicking, or rattling sounds in the lungs. Crackles happen when a person breathes in and the small airways open. Doctors can usually hear crackles as someone inhales.

Doctors may classify crackles as coarse or fine. The difference between these comes from the size of the airway opening. For example, smaller airways produce higher-pitched, fine crackles.


Rhonchi resemble snoring. They happen when something blocks the airways or when airflow becomes turbulent as it passes through the large airways. This sound can occur in expiration, or both inspiration and expiration, but never solely in inspiration.


Wheezes are high-pitched sounds. Air movement through constricted narrow airways causes wheezes. Like rhonchi, this sound can happen as someone breathes out or breathes in and out, but it never occurs just when someone breathes in.


Stridor is a wheeze-like sound. Usually, an airflow blockage in the windpipe or the back of the throat causes this sound. Unlike wheezes, stridor occurs during inspiration and is only in the upper airways.


The pleura are protective, cushioning layers of tissue. They cover the outside of the lungs and the inside of the chest wall. If the pleura become inflamed, they can rub against each other, causing an adventitious breath sound.

Rubs are typically louder than the other sounds because it occurs on the chest wall. Rubs arise during the same point in the respiratory cycle as a person breathes both in and out.

Various health conditions may cause adventitious sounds, including:


Pneumonia occurs when viruses, bacteria, or fungus cause an infection in one or both lungs. The infection causes the air sacs of the lungs to fill up with pus or fluid.

Symptoms of pneumonia include:

  • fever
  • a cough that produces phlegm
  • chest pain
  • shortness of breath
  • chills
  • vomiting
  • nausea
  • diarrhea

The treatment that doctors use for pneumonia depends on the germ causing the initial infection. They can treat bacterial pneumonia and some types of fungal pneumonia with antibiotics.

If an individual has viral pneumonia, antibiotics will not work. Instead, a doctor may prescribe antiviral medications.

Heart failure

Heart failure, which doctors sometimes call congestive heart failure, means that someone’s heart does not pump as well as it should, and it cannot supply the body with enough blood.

The symptoms of heart failure include:

  • shortness of breath
  • persistent wheezing or coughing
  • increased heart rate
  • tiredness
  • lack of appetite
  • swelling in the legs, feet, or ankles
  • nausea
  • confusion

Doctors can treat heart failure with options including:

  • medications
  • lifestyle changes
  • devices
  • surgical procedures

Chronic obstructive pulmonary disease (COPD)

COPD is a group of lung diseases, including emphysema and chronic bronchitis. It causes a person to have problems with the lungs’ airflow and breathing-related problems.

Symptoms of COPD include:

  • frequent wheezing or coughing
  • excess mucus, phlegm, or sputum production
  • shortness of breath
  • difficulty taking a deep breath

Treatment of COPD includes:

  • medication
  • quitting smoking
  • pulmonary rehabilitation
  • avoiding air pollutants and lung infections
  • supplemental oxygen


The bronchial tubes are airways that bring air to the lungs. If an individual has bronchitis, it means that these airways are inflamed.

There are two types of bronchitis, acute and chronic. People with chronic bronchitis have COPD.

Symptoms of bronchitis include:

  • a cough that produces mucus
  • shortness of breath
  • wheezing
  • a slight fever
  • chest tightness

Treatment for bronchitis typically includes:

  • rest
  • using a humidifier
  • plenty of fluids
  • acetaminophen (Tylenol) to treat fever

Those who experience wheezing may benefit from inhaled medication.

Vesicular breath sounds and bronchial breath sounds are two types of normal breath sounds.

Vesicular breath sounds are soft, low-pitched sounds that happen as someone breathes in and continue about one-third of the way through expiration. Bronchial sounds are loud, hard, and high-pitched, and their expiratory sound lasts longer than their inspiratory sound.

If an individual wants to listen for breath sounds, they should be sitting in a quiet room with no other sounds to detract from their breath sounds. The person should take deep breaths so that the individual who is listening can hear any unusual sounds.

The person should start listening at the front and top of the chest and move downward until there is no breath sound. Then, they should listen to the back of the chest, again, starting at the top and moving down until they can hear no breath sound.

To ensure they do not miss any sounds, the person listening should hear at least one complete respiratory cycle at each site.

When completing this examination, a person should listen for the following:

  • quality of the breath sounds
  • the intensity of the breath sounds
  • presence of adventitious sounds
  • differences between breath sounds on both sides

If someone notices that their skin has a bluish discoloration, they should seek medical attention. This condition is known as cyanosis and means that the tissues are not getting enough oxygen.

If individuals have severe trouble breathing, nasal flaring, or shortness of breath, they should also seek their doctor’s advice.

Additionally, people should contact their doctor if they experience any abnormal breathing sounds, such as wheezing.

Adventitious breath sounds are any sounds that occur in addition to normal breathing sounds. They can include:

  • crackles
  • rhonchi
  • wheezes
  • stridor
  • rubs

Some of these sounds happen when someone breathes in, others only occur when someone breathes out, and some can occur in both stages. Adventitious sounds are a sign of a problem within the respiratory system.

Some conditions that cause adventitious sounds include:

  • pneumonia
  • heart failure
  • COPD
  • bronchitis

People should seek immediate medical attention if they have:

  • signs of blue skin
  • nasal flaring
  • severe difficulty breathing
  • shortness of breath

A doctor should also examine an individual experiencing prolonged wheezing or other abnormal breath sounds to determine the underlying reason.