# Hearing Aids for One-Sided Hearing Loss: CROS and BiCROS Explained - Source: https://fairfieldhearing.in/blogs/types-technology/cros-hearing-aids-one-sided-hearing-loss - Publisher: Fairfield Hearing Clinics (https://fairfieldhearing.in) - Author: Shahabuddin Khan, Director · Hearing Care Professional - Medically reviewed by: Sahil Khan - Published: 23 Oct 2026 · Updated: 23 Oct 2026 > A CROS hearing aid helps people with little or no usable hearing in one ear by sending sound from the poorer side wirelessly to a hearing aid on the better ear. Who it suits, what it can and cannot do, BiCROS, alternatives such as bone-conduction devices and cochlear implants, and why an ENT check comes first. ## Key takeaways - CROS sends sound from the deaf side to a hearing aid on the good ear, overcoming the head shadow. - BiCROS also amplifies sound for a better ear that has some hearing loss. - CROS does not restore two-eared hearing or the ability to locate sounds. - Sudden hearing loss in one ear is an emergency — see an ENT doctor the same day. - Alternatives include bone-conduction devices and, for some people, a cochlear implant. ## What is a CROS hearing aid? A CROS hearing aid is a two-part system for people who have little or no usable hearing in one ear but good hearing in the other. CROS stands for **contralateral routing of signal**: a small microphone unit worn on the poorer ear picks up sound and sends it wirelessly to a hearing aid on the better ear, so you hear sounds from your “deaf” side through your good ear [1][4]. A **BiCROS** system works the same way but also amplifies sound for the better ear, for people who have some hearing loss in that ear too [1][4]. ## Who is a CROS hearing aid for? A CROS hearing aid is for people with **single-sided deafness** — a severe or profound hearing loss in one ear that an ordinary hearing aid cannot help, with normal or near-normal hearing in the other ear. Common reasons include sudden hearing loss, a past ear infection or injury, mumps, ear surgery, or a hearing loss present since birth. BiCROS is for people whose better ear also has a hearing loss that needs a hearing aid. ## What problems does one-sided hearing loss cause? One-sided hearing loss makes it hard to hear people on your deaf side, to follow conversations in noisy places such as restaurants, family gatherings and meetings, and to tell where a sound is coming from. Your head blocks sound coming from the deaf side before it reaches the good ear — this is called the **head shadow effect** [1]. ## What can a CROS hearing aid do — and not do? A CROS hearing aid helps you hear speech and sounds from your deaf side by overcoming the head shadow, so you no longer have to turn your head or rearrange seating [1]. It does **not** restore true two-eared hearing: everything is still heard through one ear, so difficulties with locating sounds and hearing in background noise remain [1]. In noisy places some people find it helps a lot; others find it brings more noise from the poor side. A trial in your own daily life is the best way to find out. ## Should I see a doctor before getting a CROS hearing aid? Yes. Anyone with hearing loss in one ear, or hearing that is much worse in one ear, should first be checked by an ENT doctor. Hearing loss in one ear can occasionally be caused by a problem along the hearing nerve, and guidelines advise doctors to look for this — usually with an MRI scan [2]. **If your hearing in one ear drops suddenly, it is an emergency.** See an ENT doctor the same day if you can. Guidelines say a hearing test should be done as soon as possible and that steroid treatment may be offered within two weeks of the start of sudden hearing loss — the sooner, the better [2]. ## What are the alternatives to a CROS hearing aid? The alternatives to a CROS hearing aid are: - **A bone-conduction hearing device**, which sends sound from the deaf side through the bones of the skull to the good inner ear. It may be worn on a headband or attached through a minor operation. Results with a bone-anchored device and with CROS are very similar [1]. An ENT surgeon advises on this. - **A cochlear implant in the deaf ear.** In 2019 the US Food and Drug Administration approved cochlear implants for single-sided deafness and asymmetric hearing loss, for people aged 5 and older [3]. Unlike CROS, an implant gives the deaf ear its own hearing, which can help with locating sounds. It requires surgery and rehabilitation; see [cochlear implant or power hearing aid?](/blogs/buying-guides/cochlear-implant-or-power-hearing-aid). - **No device** — some people manage well with tactics such as sitting with their good ear towards the speaker. ## Which brands make CROS hearing aids? Most major hearing aid brands make CROS systems that pair with their own rechargeable receiver-in-canal hearing aids — including Phonak, Signia, ReSound, Unitron, Widex and Bernafon. A CROS unit only works with a compatible hearing aid of the same brand and generation, so both parts are chosen together. Our [hearing aid price list](/hearing-aid-price-list) shows current prices; for example, ReSound Vivia CROS systems are listed there. ## How much does a CROS system cost? A CROS system costs about the same as one rechargeable receiver-in-canal hearing aid plus the CROS transmitter, and the price depends on the brand and technology level. Prices at Fairfield are shown per ear on our [price list](/hearing-aid-price-list); your final price is confirmed in writing after your hearing test. ## Can I try a CROS hearing aid at Fairfield? Yes. Fairfield Hearing Clinics tests your hearing in both ears, explains whether CROS, BiCROS or another option suits you, and lets you try a CROS system before you decide. If your hearing loss is new or has not yet been checked by an ENT doctor, we refer you first. [Book a free hearing test](/hearing-test). ## References 1. Cambridge University Hospitals NHS Foundation Trust (UK). *Single sided deafness (audiology).* https://cuh.nhs.uk/clinics/single-sided-deafness-ssd 2. American Academy of Otolaryngology–Head and Neck Surgery. *Sudden Hearing Loss Update* (summary of the 2019 Clinical Practice Guideline: Sudden Hearing Loss, Chandrasekhar SS et al.). https://bulletin.entnet.org/home/article/21247640/sudden-hearing-loss-update 3. ASHA Leader. *FDA approves cochlear implants for single-sided deafness, asymmetric hearing loss* (2019). https://leader.pubs.asha.org/do/10.1044/fda-approves-cochlear-implants-for-single-sided-deafness-asymmetric-hearing-loss/full/ 4. Phonak AG. *Phonak CROS System: an innovative solution for total unilateral hearing loss* (technical paper, 2010). https://phonak.com/content/dam/phonak/en/evidence-library/white-paper/technical-paper/Insight_Phonak_CROS_System.pdf ## Frequently asked questions ### What does CROS stand for? CROS stands for contralateral routing of signal — sound from one side is routed to the opposite ear. ### Can a normal hearing aid help one-sided deafness? Not if the poorer ear has severe or profound loss that an ordinary hearing aid cannot help. A CROS system routes that side’s sound to the better ear instead. ### Does a CROS hearing aid work with any hearing aid? No. A CROS transmitter works only with a compatible hearing aid of the same brand and generation. ### Should I see a doctor before getting a CROS hearing aid? Yes. Hearing loss in one ear should be checked by an ENT doctor first, and sudden loss needs same-day attention. --- Book a free hearing test with Fairfield Hearing Clinics: https://fairfieldhearing.in/book-a-test · Phone +91-9811418578