CROS Hearing Aid
A CROS (contralateral routing of signals) hearing aid system is designed for people with hearing loss in one ear and normal or near-normal hearing in the other. A microphone worn on or near the non-hearing ear picks up sounds from that side of the head and transmits them wirelessly to a receiver worn in the hearing ear. This allows the person to perceive sounds from their poorer side without turning their head.
Without a CROS system, someone with single-sided deafness may struggle to follow conversations when a speaker is positioned on their poorer side, miss environmental sounds from that direction, and experience the "head shadow" effect, where the head itself blocks sound from reaching the better ear when it originates from the worse side. CROS addresses this by routing the signal around the head.
Modern CROS systems are wireless and relatively discreet. The person wears a transmitter device on the deaf ear and a receiver in the hearing ear. When the hearing ear itself also has some hearing loss requiring amplification, a BiCROS configuration is used instead. CROS differs from bone-anchored hearing systems in that it does not require surgery. Audiologists assess CROS candidacy based on the degree and type of hearing loss and the person's daily listening demands.
