If you have normal hearing in one ear and little to no hearing in the other, a regular hearing aid usually won't help. This is where CROS and BiCROS hearing aids come in — specialised devices built for single-sided deafness (SSD) and unilateral hearing loss. Browse our full range of CROS hearing aids to see the latest 2026 options, or keep reading to understand exactly how CROS and BiCROS differ and which one is right for you.
What Is Single-Sided Deafness (SSD)?
Single-sided deafness means you have little to no usable hearing in one ear, while the other ear hears normally or close to normally. It can be caused by illness, injury, acoustic neuroma, sudden sensorineural hearing loss, or an unknown cause present from birth. People with SSD often struggle to:
- Locate where sounds are coming from
- Follow conversations in noisy environments like restaurants
- Hear people speaking on their "bad" side (known as the head shadow effect)
- Feel fatigued from constantly turning their head toward sound
Standard hearing aids don't solve this problem, because amplifying sound on a completely deaf ear simply doesn't work. That's exactly why CROS and BiCROS hearing aid systems exist.
What Is a CROS Hearing Aid?
CROS stands for Contralateral Routing of Signal. A CROS system is designed for people who have:
- No usable hearing in one ear (the "deaf" ear)
- Normal or near-normal hearing in the other ear (the "good" ear)
How it works: A small microphone device is worn on the non-hearing ear. It picks up sound from that side and wirelessly transmits it to a receiver worn in the good ear. The good ear then hears sound from both sides of the head — without any amplification added, since that ear doesn't need it.
Best for: People with one completely deaf ear and one ear with fully normal hearing.
What Is a BiCROS Hearing Aid?
BiCROS stands for Bilateral Contralateral Routing of Signal. It works almost identically to CROS, with one key difference: BiCROS is designed for people who have:
- No usable hearing in one ear
- Some degree of hearing loss (not normal hearing) in the other ear
How it works: Just like CROS, a microphone on the deaf ear wirelessly sends sound to the better-hearing ear. But instead of a simple receiver, the better ear wears an actual hearing aid that also amplifies the sounds it picks up directly — compensating for hearing loss on that side too.
Best for: People with one completely deaf ear and mild to moderate hearing loss in the other ear.
CROS vs BiCROS: Key Differences at a Glance
| Feature | CROS Hearing Aid | BiCROS Hearing Aid |
|---|---|---|
| Deaf ear | No usable hearing | No usable hearing |
| Better ear | Normal / near-normal hearing | Some hearing loss present |
| Function on better ear | Transmits sound only, no amplification | Transmits sound AND amplifies |
| Ideal candidate | Unilateral hearing loss with one fully normal ear | Asymmetrical hearing loss on both sides |
| Devices worn | 2 (transmitter + receiver) | 2 (transmitter + hearing aid) |
| Connectivity | Wireless, often Bluetooth-enabled | Wireless, often Bluetooth-enabled |
Top CROS & BiCROS Brands in 2026
Most major hearing aid manufacturers now offer dedicated CROS and BiCROS systems, including:
- Phonak CROS – built on the Lumity and Infinio platforms with AutoSense OS for automatic sound adjustment across environments, and full compatibility with the Roger microphone ecosystem
- Signia CROS – compatible with Signia's IX platform, offering RealTime Conversation Enhancement even for single-sided users
- Oticon, Widex, and Resound also offer their own CROS/BiCROS pairings built on their latest rechargeable platforms
Most 2026 CROS and BiCROS systems are rechargeable, use Bluetooth for phone calls and streaming, and can be fine-tuned remotely through a smartphone app — a big step up from the wired CROS systems of a decade ago.
Which One Do You Need?
The honest answer is: a hearing test will tell you. Broadly speaking:
- If your better ear tests as normal hearing, you'll most likely be fitted with a CROS system.
- If your better ear shows some measurable hearing loss, even mild, a BiCROS system is usually the better fit, since it amplifies that ear as well as rerouting sound from the deaf side.
An audiologist will confirm this with a full hearing evaluation, since even small differences in your better ear's hearing thresholds can change the recommendation.
What to Expect When You Start Wearing CROS or BiCROS
Adjusting to a CROS or BiCROS system can take a little time, especially if you've lived with single-sided deafness for years. Common experiences include:
- An initial "surround sound" sensation that feels unusual at first
- Noticeably better speech understanding in noisy or group settings within the first few weeks
- Reduced neck strain from no longer needing to turn your head toward sound
- A short adjustment period as your brain relearns to process sound from both sides
Most providers offer a trial period so you can experience real-world benefit before committing, since CROS and BiCROS are a genuinely different listening experience compared to standard hearing aids.
Frequently Asked Questions
What is the main difference between CROS and BiCROS hearing aids? CROS is for people with one deaf ear and one ear with fully normal hearing. BiCROS is for people with one deaf ear and some hearing loss in the other ear, since it also amplifies sound in that ear.
Can CROS or BiCROS restore hearing in my deaf ear? No. Neither system restores hearing in the non-hearing ear. Instead, they transmit sound from that side to your better ear, so you can still perceive sound from all directions.
Do CROS and BiCROS hearing aids work with phone calls and Bluetooth? Yes, most 2026 CROS and BiCROS systems support Bluetooth connectivity for phone calls and audio streaming from compatible smartphones.
How long does it take to adjust to a CROS or BiCROS system? Most people notice a clear improvement in speech understanding within the first few weeks, though full adjustment can take a bit longer as your brain adapts to processing sound from both sides again.
Final Verdict
CROS and BiCROS hearing aids solve a problem that standard hearing aids simply can't: hearing loss that's isolated to one ear. If your better ear hears normally, CROS is likely your solution. If your better ear also has some hearing loss, BiCROS will serve you better by amplifying that ear too. Either way, the right choice comes down to a proper hearing evaluation — book one with a licensed audiologist to find the CROS or BiCROS system that fits your hearing profile in 2026.