When we think of normal hearing, we don’t usually stop to think about how many ears we’re using. Unilateral hearing loss (UHL) can be overlooked, though, because individuals with UHL often do well in quiet environments. Once a listening situation becomes more difficult (such as in a noisy restaurant or in a classroom), the auditory system is significantly affected.
To better understand the difficulties associated with UHL, let’s examine the advantages of binaural hearing: binaural summation, head shadow effects, squelch effects, localization, and binaural release from masking.
- Binaural summation is the fact that the threshold (softest sound heard) level for two ears is better than the threshold for each ear alone. Therefore, a stimulus such as speech presented to one ear alone must be louder in intensity than speech presented to both ears simultaneously to be perceived as the same loudness. This advantage contributes to ease of listening and improved speech recognition abilities when both ears are equal.
- Head shadow effect is when the intensity of a sound is reduced when sound travels from one ear to the other side of the head. The head actually softens the sound coming from one direction. When noise is coming into the better ear and the speech signal is coming into her poorer ear, this would create the least favorable listening situation.
- Localization, the ability to know where a sound is coming from, is yet another binaural advantage. Since symmetrical hearing between the two ears is required to accurately determine the location of a sound, children with hearing loss in one ear and normal hearing in the other ear often have a difficult time with this skill.
- Binaural release from masking: The squelch effect is best explained as the “cocktail party effect.” That is, a normal listener can attend to a conversation in the presence of background noise due to a phenomenon called binaural release from masking. A signal in the presence of noise is more easily detected when the signal and noise are presented to both ears rather than to one ear alone; therefore, a listener with hearing loss in one ear will have difficulty listening in the presence of background noise.
Without these binaural advantages, it becomes easier to explain why someone with a unilateral hearing loss may have difficulty in demanding listening environments, such as a workplace or classroom. Some signs of unilateral hearing loss can include:
- Difficulty hearing in background noise, particularly if the speaker is on one side
- Increased mental fatigue at the end of the day. Constantly deciphering out what you want to hear from noise is hard work for our brains!
- Preference of an ear when speaking on the phone
- Difficulty localizing sound sources
While there can be many causes of UHL (e.g. infection, head injury, acoustic trauma, acoustic nerve lesion, or congenital), it’s important to know that there are options available to help you achieve your hearing goals.
- Traditional hearing aid: If your audiologist has determined that your hearing loss is candidate for traditional amplification, such as a hearing aid, there are many styles available.
- CROS systems: Contralateral Routing of Signal (CROS) systems are comprised of one receiver and one transmitter worn on each ear. The transmitter picks up acoustic information from the poorer ear and wirelessly transmits it to the receiver worn on the good ear.
- Bone conduction amplification: Bone amplification is another type of CROS system that works using our bodies’ natural resonance abilities of our bones. Our cochleae, which house our hearing organs, are encased in our mastoid bone. A bone conduction processor, whether worn via soft band or surgically implanted, on the impaired side will acoustically transfer information to the better-hearing cochlea on the other side without the need to wear any equipment on the good ear.
If you think you or a loved one are experiencing a unilateral hearing loss, or would like to try a new option to help you hear better, do not hesitate to call us and schedule a demo today!