Assistive listening devices are primarily used to:

Assistive listening devices are designed to enhance sound quality, particularly in challenging listening environments. They work by amplifying specific sounds or frequencies to improve clarity and intelligibility for the user. This can be especially beneficial in settings such as classrooms, theaters, or during conversations in noisy areas. The primary function of these devices is not to repair hearing loss, as hearing aids do; rather, they augment the auditory input to help individuals better understand speech and other sounds.

While options like repairing hearing loss or substituting hearing aids might seem related, they do not accurately describe the primary role of assistive listening devices. Instead, they are meant to be used in conjunction with hearing aids or independently to provide additional support in hearing-sensitive situations. Therefore, enhancing sound quality is the most appropriate characterization of their primary purpose.