What type of hearing loss is characterized by impairment in one ear?

The type of hearing loss characterized by impairment in one ear is unilateral hearing loss. This condition affects only one ear, which may lead to difficulty in localizing sounds and understanding speech in noisy environments, as the auditory signals received from the impaired ear are lacking.

Bilateral hearing loss, in contrast, affects both ears. Symmetrical hearing loss refers to a similar degree of hearing loss in both ears, while asymmetrical hearing loss indicates different levels of impairment in each ear. Therefore, unilateral hearing loss distinctly identifies the condition as being confined to just one ear, making it the correct choice for this question.