Who they’re for
Cochlear implants are considered for sensorineural loss averaging 60 dB HL or more in both ears,1 or 90 dB HL or more in one ear with 55 dB HL or better in the other.2
How the simulator models them
A noise vocoder simulates implant processing.3 The implanted ear hears only the implant, so the audiogram does not shape what it hears.
When both ears meet the criteria, both get an implant. When only one ear does, only that ear gets one, and the other ear still hears through its hearing loss, with a hearing aid unless you switch it off.
OTOF
With OTOF, hearing aids usually help little: they make sound louder, but the inner hair cells can’t pass it on to the hearing nerve.4 Cochlear implants go around the synapse and stimulate the nerve directly, so they usually work well.
What does reach the nerve loses its timing, a hallmark of auditory neuropathy. In one study, people with auditory neuropathy needed a sound's loudness to rise and fall about 10 dB more than people with normal hearing before they noticed it change, and they lost track of fast changes sooner.5 The simulator does the same to every OTOF profile's ears that don't have an implant: in each third-octave band, the sound's ups and downs are made 10 dB shallower and smoothed, while its average level stays the same. That blurs speech in time, with hearing aids too, and it's why words can stay hard to make out once they're loud enough to hear.
Sources
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T. A. Zwolan, K. C. Schvartz-Leyzac, and T. Pleasant, "Development of a 60/60 guideline for referring adults for a traditional cochlear implant candidacy evaluation," Otology & Neurotology 41, no. 7 (2020): 895–900. ↩
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American Speech-Language-Hearing Association, "FDA approves cochlear implants for single-sided deafness, asymmetric hearing loss," The ASHA Leader (2019). ↩
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R. V. Shannon et al., "Speech recognition with primarily temporal cues," Science 270, no. 5234 (1995): 303–304. ↩
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U.S. Food and Drug Administration, FDA approves first-ever gene therapy for treatment of genetic hearing loss under national priority voucher program (April 23, 2026). ↩
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F.-G. Zeng, S. Oba, S. Garde, Y. Sininger, and A. Starr, "Temporal and speech processing deficits in auditory neuropathy," NeuroReport 10, no. 16 (1999): 3429–3435. ↩