Single-Sided Deafness: Causes and CROS Hearing Aid Solutions
July 12, 2026 · By Hearing Comforts Clinical Team · 5 min read
Single-sided deafness (SSD), also called unilateral hearing loss, means having normal or near-normal hearing in one ear and significant hearing loss — sometimes total — in the other. It's more common than most people realise and often misunderstood.
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What Causes Single-Sided Deafness?
SSD can result from sudden sensorineural hearing loss, acoustic neuroma (a benign tumour on the hearing nerve), Meniere's disease, chronic ear infections, head trauma, or in some cases, an unknown cause. If you notice sudden hearing loss in one ear, seeing a specialist quickly matters.
Why One-Sided Hearing Loss Is Harder Than People Expect
Hearing with two ears helps the brain locate where sound is coming from and separate speech from background noise. With SSD, everyday situations — a colleague speaking from your "bad" side, a busy restaurant, or traffic while walking — become genuinely exhausting, even though hearing in the "good" ear tests as normal.
How a CROS Hearing Aid Helps
A CROS (Contralateral Routing of Signal) system uses a small microphone on the affected ear that wirelessly sends sound across to a receiver worn on the better-hearing ear. You still only hear from one ear, but you no longer miss what's happening on your deaf side.
Getting Evaluated
If you or a family member has hearing loss in only one ear, a comprehensive hearing test can confirm the diagnosis and determine whether a CROS system — available from Phonak, Oticon, Starkey and other brands — is the right solution for you.
Frequently Asked Questions
Can single-sided deafness be treated?
While the underlying hearing loss in the affected ear often cannot be reversed, CROS hearing aid systems effectively route sound from the deaf side to the hearing ear, significantly improving awareness and reducing listening fatigue.
Is sudden hearing loss in one ear an emergency?
Sudden hearing loss in one ear should be evaluated by a specialist as soon as possible, since some causes respond much better to early treatment.
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