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Unilateral Hearing Loss and Deafness: The Mechanisms and Solutions for Single-Sided Hearing

An illustration of a young girl holding her hand up to her ear with question marks surrounding her

The intricate process by which our brains compute sounds is complex and depends on external and internal workings. From the outer ear to the concha, the tympanic membrane, the cochlea, and the auditory (vestibular) nerve, every component contributes to how we perceive and experience sound. The effects of single-sided hearing loss (or unilateral hearing loss) are not often discussed in conversations regarding hearing impairments. And yet, this type of hearing loss is not uncommon. 

What exactly is one-sided deafness and how do specialized hearing aids help? 

Let’s explore this little-discussed type of hearing loss and the options available to you. 

What is Unilateral Hearing Loss or One-Sided Deafness? 

Unilateral hearing loss (UHL) is the broader category that refers to loss of hearing or diminished hearing in one ear, while the other ear maintains normal hearing abilities. Unilateral hearing loss can range from severe to mild and develop later in life or early in childhood. 

Single-sided deafness falls under the category of unilateral hearing loss. The difference is that the reduced function of one ear is so severe that it is considered completely deaf. In these cases, hearing aids don’t do much. 

The prevalence of unilateral hearing loss as demonstrated by a recent study suggests that 7.2% of Americans suffered from some form of UHL, with 5.7% showing mild symptoms and 1.5% experiencing moderate or worse.

What is the Acoustic Head-Shadow Effect?

The human auditory system is binaural; it is designed to hear from both ears in order to assist with sound localization, sound improvement, and spatial awareness. When this fails or there is a problem in one ear, the person must contend with what is known as the acoustic head-shadow effect. This ‘effect’ happens when a person has single-sided hearing loss or deafness and it is up to one ear to produce the sound from both sides of the head. 

If we consider that sound comes in from one direction—much like light— the shape and mass of the head can create a shadow or block some of this light. The same thing happens with sound. So when a person cannot process sound from one side of the head, the head itself creates a shadow and might entirely block out some of the incoming sounds that cannot go around the head. 

So if someone has hearing loss in their right ear, sounds coming in from that side will be considered ‘in the shadow.’ In order to process that sound, the patient must turn their head or the sound must travel around the head and reach the left ear. In environments where there is a lot going on, this will make it more difficult to decipher sounds and speech. 

Along the same vein, when a person has binaural hearing, the head shadow effect can be beneficial in blocking sound coming from a different direction. For example, if someone is listening to someone speak from their right ear and there is a car horn blaring from the direction of the left ear, the head shadow effect blocks that horn to allow the person to distinguish the speech from the right ear. 

The Effects of One-Sided Hearing Loss 

The effects of unilateral hearing loss are often underrepresented in the hearing loss community. And yet, profound hearing loss in one ear will have significant effects on a person’s day-to-day life and interactions. 

This type of hearing loss can mean a person:

  • Will have trouble localizing sounds 
  • Might have difficulty understanding speech or isolating sounds in a noisy environment
  • Has an affected ability in social interactions due to impaired hearing

What Causes Unilateral Hearing Loss?

Just like every other form of hearing loss, the root causes can vary and/or be a combination of several factors or conditions. Some of the identified causes of unilateral hearing loss include:

  • Congenital hearing loss
  • Viral infections
  • Severe traumatic brain injuries
  • Childhood measles or mumps
  • Acoustic neuroma

What Solutions Exist for People With Unilateral Hearing Loss or Deafness? 

Thanks to decades of study and research, the area of hearing aid technology has made incredible advancements. The most common solutions involve rehabilitative options that reroute the acoustic signal from the non-hearing ear to the functional ear. These are known as Contralateral routing of signal (CROS) hearing aids that have been used as a way to reroute sound. 

There are several options for people out there with unilateral hearing loss or deafness. Siemens company— one of the oldest and most trusted hearing aid manufacturers— is a leading company in the production of such devices. These CROS hearing aids consist of in-the-ear devices that include a microphone and a receiver. The microphone is used in the ear with limited hearing function, while the receiver is used in the functioning ear. 

The way these hearing aids work is that they act as a substitute for the non-functioning ear and replicate the effect of binaural hearing. This makes it easier to differentiate sound and understand speech; at the same time, it can help with spatial awareness.

Our Mission is Your Hearing Solutions, Work with Hearing Specialists in El Paso

Here at Mission Hearing, we are on the cutting-edge of new advancements and technology in the world of hearing aids and hearing loss. Whether you are suffering from minor hearing loss or severe hearing impairment, we help you find the solutions that are right for you. 

Want to know more about how to hear better? Call us today


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