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Understanding Single-Sided Deafness (SSD)

Single-Sided Deafness (SSD) is a condition where an individual has little to no hearing in one ear while the other ear retains normal or near-normal hearing ability. This condition can be caused by a variety of factors, including viral infections, acoustic neuromas, Ménière’s disease, idiopathic sudden sensorineural hearing loss, or head trauma. People with SSD often struggle in environments where sound is coming from multiple directions, leading to difficulties in localisation, communication, safety concerns, and reduced spatial awareness.

To address these challenges, audiologists often recommend Contralateral Routing of Signal (CROS) or Bilateral Contralateral Routing of Signal (BiCROS) hearing aids. These solutions help individuals with SSD regain access to sound that would otherwise be lost due to their hearing impairment.

How CROS Hearing Aids Work

CROS hearing aids are specifically designed for individuals with SSD who have normal hearing in their better ear. The system consists of two parts: a microphone placed on the ear with the significant hearing loss, and a receiver/transmitter in the better-hearing ear. The microphone captures sound from the non-hearing side and wirelessly transmits it to the hearing ear, allowing the user to perceive sounds from both sides of their body.

This setup is particularly beneficial in situations where the user needs to engage in conversation but has difficulty hearing due to someone speaking on their non-hearing side. By routing the sound to the functioning ear, a CROS hearing aid provides a more balanced auditory experience and enhances communication in social and professional settings. It is really amazing how we can trick the brain into thinking it is hearing from the otherwise non-functional ear. You can even hold a phone up to the ear that has limited hearing, and hear the conversation!

How BiCROS Hearing Aids Differ

A BiCROS hearing aid is similar to a CROS system but is designed for individuals who have some degree of hearing loss in their better ear. In this case, the system not only transmits sounds from the non-hearing ear but also amplifies sounds in the better ear according to the user’s specific hearing needs.

BiCROS hearing aids are ideal for those who experience asymmetrical hearing loss, meaning one ear has profound hearing loss while the other has mild to moderate hearing loss. These devices ensure that the user receives adequate amplification in the better ear while simultaneously capturing and transmitting sounds from the non-hearing side.

Benefits of CROS and BiCROS Hearing Aids

1. Improved Sound Awareness

CROS and BiCROS systems provide a more natural listening experience by ensuring that sound from both sides of the environment is accessible. This helps users avoid missing important auditory cues, whether in conversations, traffic, or other daily activities.

2. Enhanced Communication

Many SSD patients struggle in noisy environments such as restaurants, meetings, or social gatherings. CROS and BiCROS hearing aids help by routing sound to the better ear, allowing users to engage in conversations more effectively without constantly repositioning themselves to hear better.

3. Reduction of the Head Shadow Effect

The head acts as a natural barrier to sound, particularly affecting high-frequency sounds. This phenomenon, known as the “head shadow effect,” makes it difficult for people with SSD to distinguish certain speech sounds. CROS and BiCROS hearing aids counteract this issue by transmitting sound from the non-hearing side, ensuring that all speech cues are heard clearly.

4. Increased Safety and Spatial Awareness

For individuals with SSD, safety can be a concern, particularly when crossing streets, riding a bike, or navigating busy environments. CROS and BiCROS hearing aids improve spatial awareness by allowing users to detect sounds from all directions, making them more aware of their surroundings.

5. Non-Surgical Solution

Unlike cochlear implants or bone-anchored hearing systems, CROS and BiCROS hearing aids offer a non-invasive solution for SSD. They provide significant auditory benefits without the need for surgical intervention, making them a preferred choice for many patients.

Limitations and Considerations

While CROS and BiCROS hearing aids offer numerous advantages, they also come with some limitations. These devices do not restore binaural hearing (true two-ear hearing) and do not completely improve the ability to localise sound. Additionally, in very noisy environments, the transmission of unwanted background noise from the non-hearing side may be distracting.

To ensure optimal results, an audiologist will assess the patient’s individual needs and program the hearing aid accordingly. Modern CROS and BiCROS devices come with advanced features such as background noise reduction, Bluetooth connectivity, and rechargeable options, making them more adaptable and user-friendly.

Choosing the Right CROS or BiCROS Hearing Aid

Several leading hearing aid manufacturers, including Starkey, Widex, Oticon, Signia Phonak, Unitron, and ReSound, offer CROS and BiCROS solutions with various features. Not every manufacturer will have what suits a specific patient. When selecting a device, patients should consider factors such as:

  • Comfort and Fit: Ensuring the device feels comfortable for extended wear.
  • Battery Life: Choosing between rechargeable and disposable battery options.
  • Connectivity: Some models offer Bluetooth streaming for phone calls and media playback.
  • Noise Reduction Features: Advanced noise filtering can improve speech clarity in complex listening environments.

Final Thoughts

For individuals with single-sided deafness, CROS and BiCROS hearing aids offer a significant improvement in their ability to hear and communicate effectively. These devices help bridge the gap created by SSD, enhancing social interactions, increasing safety, and improving overall quality of life.

If you or a loved one has SSD and is considering a CROS or BiCROS hearing aid, consulting with our Audiologist at The Audiology Place is the best way to determine the most suitable solution. With advancements in hearing aid technology, there are now more options than ever to help individuals with SSD regain confidence in their hearing abilities.

author avatar
Dr Signe Steers Audiologist
Welcome to my clinic. With nearly 20 years of experience, I have dedicated my career to enhancing the hearing health of individuals across all stages of life, from infants to the elderly. My passion for Speech and Hearing Science was sparked early on, driven by the understanding that improved hearing significantly enhances education, behaviour, and overall well-being. My career has taken me from presenting research at the World Health Organization to working in rural communities in the Philippines, where I helped developed systems that improved health and educational outcomes for disadvantaged populations. Last year I completed a Doctorate in Audiology at A.T. Still University in Arizona. Dr Signe Steers (Peitersen) holds a Bachelor of Speech and Hearing science from Macquarie University, Sydney, A Masters in Clinical Audiology from Macquarie University Sydney, and a Doctor of Audiology from A.T. Still University Arizona. Signe is a full member of Audiology Australia and Independent Audiologists Australia.