Single-Sided Deafness

Single-sided deafness (SSD) is defined as a condition when one has non-functional hearing in one ear that does not receive benefit from traditional amplification and normal or near normal hearing in the other ear.

While the precise incidence of SSD is unknown, the prevalence is estimated at 3-6% of the population (Baguley et al., 2006). Those with SSD experience problems hearing in background noise, difficulties with localization and spatial hearing and difficulties hearing those who are near their non-functional side (Cire, 2012).

Causes of SSD

  • Presence or removal of an acoustic neuroma (a benign, slow-growing tumor in the cerebellopontine angle).
  • Sudden idiopathic loss due to an unexplained viral infection often causing permanent damage to the hair cells and fine structures of the cochlea.
  • Vascular issues that damage the auditory pathway.
  • Blunt trauma to the head which results in a transverse fracture of the temporal bone.
  • Meniere’s disease whereupon excess fluid pressure in the inner ear causes long-term damage to the cochlea.
  • Congenital or genetic issues.
  • Autoimmune ear disease.
(Cire, 2012)


  • Do nothing.
  • CROS/BICROS hearing aid: CROS is an acronym for contralateral routing of signals. It consists of two parts, a microphone (transmitter) worn at the bad ear and a hearing aid (receiver) worn at the good or better ear. The microphone at the dead ear picks up sounds and routes the sound from the dead ear to the better ear. While previous wireless devices had issues with excessive battery drain, the new Siemens/Signia CROS device provides clear transmission of sound without excessive battery drain. We have had great success with this instrument. Learn more about Signia and Siemens hearing instruments
  • Bone conduction solutions: Originally referred to as BAHA (bone anchored hearing aid), this solution consists of osseointegrated devices which include an implant, an external abutment or a magnet and a sound processor. The sound processor sends vibrations via the abutment or magnet to the implant through the skull through bone conduction to the better hearing ear. Surgical implantation is required and can be completed through Sacramento ENT . Following a specified healing period, the sound processor is fit to the patient. At SENT Hearing Aid Center, we offer bone-conduction devices from these manufacturers:

What a CROS Aid or Bone Conduction Device Does:

Helps you hear when someone is speaking at the “bad ear” by sending the sound to the “good ear.”

What a CROS Aid or Bone Conduction Device Does Not Do:

  • It does not improve sound localization. Two ears provide cues that allow us to localize sounds. When one ear is taken out of the equation, confusion occurs, and we have difficulty identifying near and distant sounds. Since all the sounds are going to one ear, localization may still be difficult.
  • This device may not help with understanding speech in noise.

Which Device is Right for You?

I have found that those who have lived with congenital, unilateral hearing loss may be better off doing nothing. They have learned how to live with the issue. If the loss was recently acquired, the CROS or BAHA may be a good option. It is always easier to start with the “non-surgical” CROS option, and at SENT Hearing Aid Center, we offer a 60 day trial on hearing aids, including the CROS.


Baguley, D., Bird, J., Humphriss, R. & Prevost, A. (2006). The evidence base for the application of contralateral bone anchored hearing aids in acquired unilateral sensorineural hearing loss in adults. Clinical Otolaryngology, 31, 6-14 Cire, G. (2012). Understanding single sided deafness: Evaluation and treatment for professionals. Audiology Online