"Hereditary deafness" refers to a condition where a person is born deaf or loses their ability to hear due to genetic factors passed down from their parents or ancestors. Full definition
BAER testing for hearing defects is another diagnostic procedure that is strongly recommended because of the high incidence of hereditary deafness in the breed. (oldenglishsheepdogclubofamerica.org)
Congenital hereditary deafness in most dog breeds is associated with 1 of 2 classical pigmentation genes responsible for white or light skin and fur coloration: piebald and merle.1 The pigment locus S has 3 recessive alleles: Irish spotting, piebald, and extreme piebald; dogs with the dominant allele have solid color. (cobradog.com)
A different form of congenital hereditary deafness is seen in the Doberman, which is also accompanied by vestibular (balance) disturbance; this deafness results from a different mechanism where hair cell death is not the result of degeneration of the stria but is instead the primary pathology. (lsu.edu)