People with unilateral hearing loss can hear normally in one ear, but have trouble hearing out of the other ear. Causes include physical trauma, or mumps (Epidemic parotitis).

Profound unilateral hearing loss is a specific type off hearing impairment when one ear has no functional hearing ability (91dB or greater hearing loss). It is known to cause:

• Irritability
• Frequent headaches, stress
• Social isolation
• Trouble figuring out where sounds are coming from.
• Variable light dizziness
• Trouble paying attention in what people are saying: Evasive behaviour.
• Lack of sound depth: any background noise (on the room, on the car) is flat and wrongly interpreted by the brain. The effect is similar to what happens when people with unimpaired hearing try to watch, on a mono TV, someone speaking in a noisy crowd.
• Inability to filter out background noise or selectively listen to only the important portion of the noise in the environment.
• For sensorineural loss, the lack of input coming from the damaged sensory apparatus can cause "ghost beeps" or ringing/tinnitus as the brain attempts to interpret the now missing sensory data. The frequency and the volume of the noise can increase according to one's physical condition (stress, fatigue, etc.). This can aggravate social problems and increase the difficulty of speech comprehension.