Crackles are much more common during the inspiratory than the expiratory phase of breathing, but they may be heard during the expiratory phase. Crackles are often associated with inflammation or infection of the small bronchi, bronchioles, and alveoli. Crackles that do not clear after a cough may indicate pulmonary edema or fluid in the alveoli due to heart failure, pulmonary fibrosis, or acute respiratory distress syndrome. Crackles that partially clear or change after coughing may indicate bronchiectasis. Crackles are often described as fine, medium, and coarse. They can also be characterized as to their timing: fine crackles are usually late-inspiratory, whereas coarse crackles are early inspiratory. Fine crackles are soft, high-pitched, and very brief. This sound can be simulated by rolling a strand of hair between ones fingers near the ears, or by moistening ones thumb and index finger and separating them near the ears. Their presence usually indicates an interstitial process, such as pulmonary fibrosis or congestive heart failure. The sounds from interstitial pulmonary fibrosis have been described as sounding like opening a Velcro fastener. Coarse crackles are somewhat louder, lower in pitch, and last longer than fine crackles. Their presence usually indicates an airway disease, such as bronchiectasis.They can also be described as unilateral or bilateral, as well as dry or moist/wet. See also
Bronchophony
Egophony
Consumption
Whooping cough
Croup
Pertussis toxin
Allergic asthma
Respiratory sounds

References
External links

Audio Breath Sounds - Multiple case studies with audio files of lung sounds. R.A.L.E. Repository - sound files of breath sounds
A papillary hidradenoma, also termed hidradenoma papilliferum or mammary-like gland adenoma of the vulva, is a rare, but nonetheless most common benign tumor that occurs in and between anal and genital regions (i.e. anogenital  area) of females. These hidradenomas are sharply circumscribed, nodular tumors that usually develop in womens anogenital area (particularly the vulva) but uncommonly occur in other sites in women and men. Papillary hidradenomas that develop outside of the anogenital region are termed ecctopic papillary hidradenomas or ectopic hidradenoma papilliferums.Anogenital papillary hidradenomas are regarded as tumors that form in anogenital mammary–like glands (MLAGs); MLAGs are a type of apocrine gland. MLAGs were once classified as abnormally located breast tissue glands (see accessory breast tissue@ https://doi.org/10.53347/rID-11125) but are now considered to be normal components of the anogenital region. Microscopically, papillary hidradenomas often resemble certain types of breast tumors. Ectopic papillary hidradenomas are thought to be tumors of apocrine glands which have an as yet unclear relationship to MLAGs.Typically, papillary hidradenomas are solitary, slow-growing, small tumors that may have been present for months to many years before the time of diagnosis. The tumors are usually symptomless but may be intermittently or constantly painful, become ulcerated, and exhibit minor levels of bleeding. The pain resulting from these tumors may be simple tenderness, more or less constant usually mild pain, or, in females, dyspareunia, i.e. pain during and just after sexual intercourse.Rarely, papillary hidradenomas have progressed to what appear to be 1) in situ malignancies (i.e.