Lung Sounds | Breath Sounds

Lung and Breath Sounds

Auscultation of Lung Sounds

Auscultation of the lungs is an essential part of physical examinations. All fields of the chest wall should be examined, including the chest wall anterior, posterior, and flanks.

Fundamentals of Lung Sounds (free module and quiz)

This module provides an overview of lung sound characteristics followed by lessons on eight selected sounds. For each lung sound lesson, you will have access to text, a lung sound recording, and a dynamic waveform video.

This website provides additional auscultation courses, reference guides, and quizzes. Certificates of achievement are also available.

Lung Auscultation Locations

Auscultation of lungs sounds should be conducted over the anterior and posterior chest walls. See the associated illustration for these locations. Many stethoscopes have chestpieces with both bell and diaphragm. Typically, start with the diaphragm but switch to the bell to hear lower-pitched sounds.

The triangle of auscultation, found on the dorsum of the thorax, has a relatively thin layer of muscle. This makes it an ideal location for lung sound auscultation. You should ask the patient to cross their arms and lean forward.

Timing and Duration

During auscultation, note the sound's timing within the respiratory cycle such as inspiratory, expiratory or more specific terms such as early expiratory.

Pitch

A lung sound's pitch (frequency) is an important characteristic. The observer should classify the sound or murmur's pitch as low, medium, or high. The stethoscope's bell can be helpful with low-pitched sounds, while the diaphragm is used for medium or high-pitched sounds.

Using Our Auscultation Lessons

Here we provide an example of lung sounds, a fine crackle.

Playback

Click the playback button on the torso to hear a short recording.

The patient was seated during auscultation.

Waveform

A waveform is a plot of the lung sound's amplitude over time. Click the play button to view this waveform and hear the corresponding lung sound. This video will loop until paused.

Bronchial Breath Sounds

Bronchial breath sounds are hollow, tubular sounds that are higher-pitched than vesicular sounds. They can be auscultated over the trachea and anteriorly along each side of the sternum, from the second to fourth intercostal spaces. Posteriorly, along the vertebral column from the third to sixth intercostal spaces.

The stethoscope's diaphragm is used for auscultating these lung sounds. There is a distinct pause in the sound between inspiration and expiration. I:E ratio is 1:3.

Bronchial Breath Sounds - Lesson, Audio, Waveform

Wheeze

Air flowing through a narrowed bronchus produces wheezes. Accordingly, these sounds will have their highest sound intensity when auscultating over or near the central airways.

Wheezes are adventitious lung sounds associated with secretions, obstructions, tumors, or airway compression. They are continuous sounds with a musical quality. High-pitched wheezes have a squeaking quality, while low-pitched wheezes are similar to snoring or moaning. The proportion of the respiratory cycle occupied by the wheeze roughly corresponds to the degree of airway obstruction.

Wheezes are also classified by when they appear in the respiratory cycle, e.g. inspiratory wheezing or a late expiratory wheeze. Moreover, information about the sound quality (monophonic or polyphonic) should be observed. These characteristics can be found in our Intermediate Lung Sounds module.

Wheeze - Lesson, Audio, Waveform

Rhonchi

Rhonchi are continuous, low-pitched adventitious lung sounds caused by fluids or secretions in the large airways. They often have a snoring, gurgling, or rattle-like quality. They are heard primarily during expiration, but will appear during inspiration in some patients. Rhonchi will usually clear or alter in sound after coughing.

Fine Crackles

Fine crackles are brief, discontinuous, popping, high-pitched breath sounds. These sounds are also similar to the sound of Velcro fasteners being pulled apart or cellophane being crumpled. Crackles can appear throughout the respiratory cycle.

Fine Crackles - Lesson, Audio, Waveform

Coarse Crackles

Coarse crackles are discontinuous, popping, or bubbling breath sounds. They are louder, lower in pitch, and of longer duration than fine crackles.

Coarse Crackles - Lesson, Audio, Waveform

Pleural Rubs

Pleural rubs are creaking or grating sounds. The sound is similar to leather against leather or walking on fresh snow on a cold day. Coughing will not alter the sound.

Pleural rubs are generated when two inflamed surfaces slide past one another, such as in pleurisy. During auscultation, try to identify a specific point on the chest wall where pleural rubs are loudest. These sounds occur with movement of the patient's chest and will stop when the patient holds her breath. They appear on inspiration and expiration. If the sound continue when the patient is holding her breath, it may be a pericardial friction rub.

Pleural Rubs - Lesson, Audio, Waveform

Stridor

Stridor is created by air flowing through an upper airway that is narrowed or obstructed. It occurs in 10-20% of extubated patients. Stridor is a loud, high-pitched crowing breath sound heard during inspiration. Stridor may also occur throughout the respiratory cycle, particularly if the condition worsens. Often it is heard without a stethoscope. Causes of stridor are obstructions, pertussis, croup, epiglottis, aspirations.

Stridor - Lesson, Audio, Waveform