Audiology Services
The specific difficulty has a name: the head shadow. Your own head blocks higher-frequency sound coming from the deaf side, so a voice on that side arrives muffled or not at all. Sitting with the good ear to the room becomes a habit, and so does missing the person on the other side of the table.
There are three established ways to address it, and they are genuinely different from one another rather than three brands of the same thing. We fit and program CROS and BiCROS systems here, we run the evaluation that establishes which route suits you, and where a surgical option is the better answer we say so and refer. Start with a hearing evaluation — the first thing to establish is whether the loss is stable, sudden, or something that needs a physician now.
At a glance
- Single-sided deafness removes sound localisation and the ability to separate voices, even though the good ear tests normally.
- CROS and BiCROS systems reroute sound from the deaf side to the hearing ear without surgery, but do not restore binaural hearing.
- Cochlear implantation is the only option that stimulates the deaf ear itself, and the FDA approved it for single-sided deafness in 2019.
- Hearing lost suddenly in one ear is a medical urgency — treatment outcomes depend heavily on how quickly it is treated.
First, is this sudden?
Hearing that disappears in one ear over hours or a couple of days is a medical urgency, not something to monitor. Sudden sensorineural hearing loss is treated with steroids and the evidence for recovery is strongly time-dependent, which means the window is measured in days rather than weeks. If this describes you, call us or your physician today rather than reading further. The same applies to one-sided loss that arrives with vertigo, or with sudden ringing on that side alone — our page on when tinnitus needs a doctor sets out the other red flags.
What CROS hearing aids do
A CROS system is two devices. A microphone sits on the deaf ear, picks up sound arriving on that side, and transmits it wirelessly to a hearing aid worn on the good ear. Nothing is implanted and nothing is surgical. What it buys you is awareness of the side you had lost: the colleague on your deaf side becomes audible, and the restaurant stops being a matter of seating strategy. What it does not buy you is binaural hearing. Sound from the deaf side is delivered to the hearing ear, so the brain still has only one ear's worth of information and true localisation does not return.
CROS and BiCROS, and which one you need
The difference is the good ear. CROS is for a normal or near-normal hearing ear: the device on that side is essentially a receiver, passing across what the deaf side picks up without amplifying what the good ear already hears well. BiCROS is for a good ear that also has some hearing loss of its own: it does the same rerouting and additionally amplifies for that ear's own prescription. Which of the two you need is decided by your audiogram rather than by preference, and it is one of the simpler decisions in this area.
Bone-anchored systems
A bone conduction device transmits sound through the skull to the working inner ear, using a processor held by a surgically placed implant or, for a trial, a softband. Like CROS it routes sound from the deaf side to the hearing cochlea, and like CROS it does not restore binaural hearing or sound localisation. Its advantages are that nothing sits in either ear canal, which suits people with chronic ear drainage or canal problems, and that the sound path avoids the canal entirely. Its cost is a minor surgical procedure. Candidacy for these is assessed with an ENT surgeon, and we will refer you for that and handle the audiological side.
Cochlear implants for single-sided deafness
This is the option most people have never heard of. In July 2019 the FDA approved MED-EL's cochlear implant systems for single-sided deafness and asymmetric hearing loss in patients aged five and over, defining SSD as profound sensorineural loss in one ear with normal or mild loss in the other. It matters because an implant stimulates the deaf ear itself. A review of the three approaches concludes that CROS and bone conduction devices reroute sound and cannot restore binaural hearing, while the cochlear implant is the only option that does, with measured gains in speech in noise, localisation and tinnitus. It is also surgery, and the deaf ear generally has to have been deaf for a limited time for it to work well.
How we help you choose
The evaluation comes first and it is not just an audiogram: we measure both ears fully, test speech understanding in noise, and talk through where your difficulty actually falls, because someone who teaches in a lecture hall and someone who works alone have genuinely different answers here. A CROS trial is the cheapest way to find out whether rerouting is enough for you, since nothing is permanent and the devices come back if it is not. If the evaluation points towards an implant or a bone-anchored system, we refer you to an established Bay Area implant centre for the surgical assessment and stay involved for the programming afterwards, so the day-to-day care stays close to home.
Tinnitus in the deaf ear
Ringing on the deaf side is common and is often the symptom people find hardest, more so than the hearing loss itself. Rerouting devices do not directly treat it, though some wearers report it recedes as the brain gets more input. Bone conduction and cochlear implants both have reported tinnitus benefit, and for implants that benefit is one of the measured outcomes rather than an anecdote. We treat tinnitus in its own right regardless of which device route you take — see tinnitus therapy for what that involves.
Frequently asked questions
Questions patients ask us
What is single-sided deafness?
Profound hearing loss in one ear with normal or near-normal hearing in the other. Because two ears are what allow you to localise sound and separate one voice from several, the practical difficulty is far greater than an audiogram of the good ear suggests — particularly in restaurants, meetings and cars.
What is a CROS hearing aid and how does it work?
A CROS system uses a microphone worn on the deaf ear to pick up sound on that side and transmit it wirelessly to a hearing aid on the good ear. It restores awareness of the side you had lost. It does not restore binaural hearing, because the sound still reaches only one working cochlea.
What is the difference between CROS and BiCROS?
CROS is for a good ear with normal or near-normal hearing, where the device simply receives what the deaf side picks up. BiCROS is for a good ear that also has hearing loss, so it reroutes and additionally amplifies for that ear's own prescription. Your audiogram decides which applies.
CROS, bone-anchored, or a cochlear implant — how do I choose?
Start with what you need back. If the goal is hearing the person on your deaf side, a CROS trial answers that quickly and without surgery. If you want the deaf ear working again, with localisation and better speech in noise, only a cochlear implant does that, and it is surgery with its own candidacy requirements. Bone-anchored systems suit people who cannot tolerate something in the ear canal. We evaluate and talk it through before anything is decided.
How long does it take to adjust to a CROS system?
Most people need a few weeks. The early oddity is that sound from your deaf side now arrives at your good ear, so your brain is receiving information it has no way to place — voices can seem to come from the wrong direction at first. That settles as the brain learns to use the signal. Wearing them consistently through that period is what makes the difference, and a follow-up visit or two is expected.
Do you fit CROS and BiCROS systems?
Yes. We fit and program CROS and BiCROS systems at both offices, and we verify them the same way we verify any fitting. If your evaluation points towards a bone-anchored device or a cochlear implant instead, we will say so and refer you for the surgical assessment while staying involved in the audiological care.
Can you get a cochlear implant for single-sided deafness?
Yes. The FDA approved cochlear implantation for single-sided deafness and asymmetric hearing loss in July 2019 for patients aged five and over. Candidacy depends on the specifics, including how long the ear has been deaf, and is established through a formal evaluation. See our cochlear implant page for what that involves.