Characteristics of breath sounds

Normal Breath Sounds (Vesicular Sounds)

Thus in health, over most of the chest, the breath sounds are low-pitched and have a relatively quiet expiratory phase. The inspiratory component originates in the lobar and segmental airways, whereas the expiratory component arises from more central airways.

Breath sounds are classified into normal tracheal sound, normal lung sound or vesicular breath sounds, and bronchial breath sound. Bronchial breath sounds are further subdivided into three types: Tubular, cavernous, and amphoric.

There are two normal breath sounds. Bronchial and vesicular . Breath sounds heard over the tracheobronchial tree are called bronchial breathing and breath sounds heard over the lung tissue are called vesicular breathing.

Lastly, bronchovesicular sounds are medium pitched sounds that have a muffled quality, and the inspiratory phase is equal to the expiratory phase. It is also important to recognize ‘abnormal’ breath sounds. The most common deviations may include: Decreased breath sounds.

Types of breath sounds

However, abnormal breath sounds may include: rhonchi (a low-pitched breath sound) crackles (a high-pitched breath sound) wheezing (a high-pitched whistling sound caused by narrowing of the bronchial tubes) stridor (a harsh, vibratory sound caused by narrowing of the upper airway)

Crackles (Rales)

Crackles are also known as alveolar rales and are the sounds heard in a lung field that has fluid in the small airways. The sound crackles create are fine, short, high-pitched, intermittently crackling sounds. The cause of crackles can be from air passing through fluid, pus or mucus.

Stridor, or noisy breathing, is caused by a narrowed or partially blocked airway, the passage that connects the mouth to the lungs. This results in wheezing or whistling sounds that may be high-pitched and audible when a person inhales, exhales, or both.

Rhonchi resemble low-pitched wheezes. They are rumbling, coarse sounds like a snore during inspiration or exploration and continuous. It may clear with coughing.

Rhonchi: Rhonchi occur due to conditions that block airflow through the large airways, including the bronchi. There may also be inflammation and fluid in these airways. Conditions such as acute bronchitis and COPD may cause rhonchi. Stridor: Stridor occurs in people with an upper airway blockage.

Crackles are defined as discrete sounds that last less than 250 ms, while the continuous sounds (rhonchi and wheezes) last approximately 250 ms. Rhonchi are usually caused by a stricture or blockage in the upper airway. These are different from stridor.

Rhonchi are often a low-pitched moan that is more prominent on exhalation. Coughing can sometimes clear this breath sound and make it change to a different sound. Crackles (Rales) Crackles are the sounds you will hear in a lung field that has fluid in the small airways.

Crackling or bubbling noises (rales) made by movement of fluid in the tiny air sacs of the lung. Dull thuds heard when the chest is tapped (percussion dullness), which indicate that there is fluid in a lung or collapse of part of a lung.