The doctor who sees a patient with breathing problems will use a stethoscope to listen to abnormal breath sounds. Apart from history and general examination breath sounds reveal a lot about the lung condition that a patient has. This was a recent review in this publication. https://www.medicalnewstoday.com/articles/322251.php
Wheezing is a high-pitched noise that is continues and may sound a bit like a whistle. In an acute asthma attack anybody nearby the patient can hear the wheezing even without a stethoscope.
Crackles or rales
This sound which sounds like a clicking or rattling when a person inhales has an association with fluid accumulation in the lungs. The physician might expect left-sided heart failure or pneumonia to be the cause of this. The crackling may sound wet or dry and could be fine or coarse.
This sound usually occurs when a person breathes in and there is a blocked upper airway. It is a high-pitched harsh sound, audible by anybody around this person. This can happen when the person has breathed in a foreign object or substance. Otherwise a traumatic neck or chest injury can cause this as well. In addition an inflammatory condition like tonsillitis, epiglottitis or croup can bring it on as well.
These sounds are lower-pitched, continuous and rough sounds that may be reminiscent to snoring. Rhonchi are generated when something like thick mucous is blocking the larger airways. Inflammation from acute bronchitis or from COPD can lead to secretions that can cause this sound.
Apart from the findings by history and from the examination the doctor may want to order further diagnostic tests. A pulmonary function test or spirometry will tell the doctor whether the breathing pattern is abnormal or normal. Asthma and COPD give a characteristic finding on spirometry. A chest X-ray will show a shadow typical for pneumonia. In an acute bronchitis case the sputum contains abnormal bacteria that show up with a culture. Usually sensitivity to a batch of different antibiotics is also part of the tests, and this is useful for treating the condition. In case of trauma to the airways a CT scan will show any structural abnormality. Bronchoscopy and possibly a biopsy are useful in case of an early bronchial cancer.
There are different types of sounds that the doctor can detect by lung auscultation using a stethoscope. Even an untrained person can hear abnormal sounds like wheezes, crackles, stridor and rhonchi. Closer listening tells the physician what abnormalities may underlie these sounds. Further tests are necessary to come to a definite diagnosis. This helps the physician to treat the underlying condition with the appropriate therapy.