Inclusion Criteria:  Age 0-27 months;  Hearing loss, as determined by auditory brainstem response (ABR) or behavioral audiometry (average of pure-tone air-conduction hearing thresholds (0.5-4 kHz; PTA) calculated from at least 2 frequencies from ABR (dB eHL) or behavioral audiometry (dB HL)):  bilateral sensorineural, mixed, or permanent conductive hearing loss with better-ear PTA > 20 dB. single-sided deafness (unilateral SNHL with PTA > 70 dB); unilateral complete aural atresia; or bilateral auditory-neuropathy spectrum disorder, as determined by ABR. Primary home language is English or Spanish, determined by electronic medical record or direct parent report.  For children with PTA > 20 dB, either:  Currently fit with hearing aid or using a cochlear implant; OR Date identified for hearing-aid fitting or cochlear-implant activation within 3 months of enrollment.  Exclusion Criteria:  Family does NOT have the intention to pursue listening and spoken language for their child, based on parent report;  Moderate to severe global developmental delay, as determined by managing audiologist and/or otolaryngologist, based on:  ICD-10 diagnosis code or chart review of medical progress notes indicating global developmental delay; presence of syndrome known to be associated with this delay (such as Trisomy 21, 22q11 syndrome, or CHARGE syndrome); OR parent report. Speech-language teletherapy received through a clinical provider outside of this study at the time of enrollment, based on parent report.  No prognosis for access to sound as determined by managing audiologist and/or otolaryngologist. All children with bilateral severe-to-profound SNHL must have imaging to confirm this criterion prior to enrollment in the study. Children will be excluded if they have bilateral severe-to-profound sensorineural hearing loss and either:  Contraindication to cochlear implantation, OR Temporal bone abnormalities that lead to great concern for poor cochlear-implant outcomes, including common cavity and/or cochlear nerve deficiency on imaging.