Some people cannot hear well. 

Some people have trouble hearing. 

Some people have trouble hearing sounds. This is called hearing loss. It can be a small problem or a big one. If a person cannot hear anything, they are called deaf. 
Hearing loss can happen at birth. It can also happen later in life. Many things cause it. Loud noises can hurt your ears. Getting older can also cause it. Some people lose tiny hair cells in their ears. This makes it hard to hear. 
Doctors use a test to check your hearing. They use an audiometer. This is a tool that makes pure sounds. They check how loud a sound must be for you to hear it. They measure this in decibels.
Many tools help people hear better. Some use hearing aids. Others use cochlear implants. These are small devices that help the ear. 
Hearing loss happens when someone cannot hear sounds as well as they should. This can be a partial problem or a total inability to hear, which is called deafness. 
Sound works by traveling in waves into our ears. Hearing loss occurs when these waves damage sensitive tissues inside.
Scientists and doctors have studied hearing for a long time. They use decibels to measure the intensity of sound. A sound at 0 dB is the softest sound an average person can hear. Sounds become uncomfortably loud above 90 dB. At 115 dB, a sound can actually cause pain. 
Many people around the world live with hearing loss. As of 2013, about 1.1 billion people have some degree of hearing loss. This causes disability for about 466 million people. 
There are many ways to help people communicate. Some people use hearing aids or cochlear implants to hear better. Others use sign language to share ideas. 
Hearing loss is the diminished ability to detect sounds that would normally be heard. This can range from a partial inability to hear to total deafness. Deafness is defined as a loss so significant that a person cannot understand speech, even with amplification. In cases of profound deafness, even the loudest sounds from an audiometer may not be detected. Total deafness means no sounds can be heard at all, regardless of the method used. 
Hearing loss occurs when sound waves enter the ears and damage sensitive tissues. One common cause is the loss of cochlear hair cells, which are tiny cells in the inner ear. There are three primary types of hearing loss. Conductive hearing loss involves how sound moves through the ear. Sensorineural hearing loss involves damage to the inner ear or the auditory nerve. Mixed hearing loss is a combination of both these types. A rare condition called auditory neuropathy occurs when the cochlea's hair cells work, but the auditory nerve does not transmit information faithfully to the brain.
Doctors categorize the severity of hearing loss using decibels (dB). This measurement tracks the increase in sound intensity required for a person to detect a sound. The categories include minimal or slight (15 to 25 dB), mild (25 to 40 dB), and moderate (41 to 55 dB). There are also moderate-severe (56 to 70 dB), severe (71 to 90 dB), and profound (greater than 90 dB) levels. A person is officially diagnosed with hearing loss when testing shows they cannot hear 25 decibels in at least one ear. 
Many different factors can cause hearing loss to develop. It can be present at birth or acquired later in life. Genetics, aging, and exposure to loud noise are common causes. Some people experience hearing loss due to infections, birth complications, or trauma to the ear or brain. Certain medications or toxins can also cause damage. Chronic ear infections are a common condition that leads to hearing loss. Additionally, infections during pregnancy, such as rubella, syphilis, or cytomegalovirus, can cause hearing loss in a child.
Global statistics show how widespread this issue is. As of 2013, approximately 1.1 billion people live with some degree of hearing loss. This causes disability in about 466 million people, which is 5% of the global population. Among those with moderate to severe disability, 108 million live in low and middle-income countries. For 65 million people, the hearing loss began during childhood.
Hearing loss is linked to several other health concerns. It is associated with an increased risk of falls, especially in older adults. There is also a link between hearing loss and cognitive decline, including mild cognitive impairment and dementia. Some researchers believe this is due to increased cognitive load or social isolation. Hearing loss can also cause secondary symptoms like tinnitus, which is ringing or buzzing in the ear. It may also cause vertigo, which is a feeling of being off-balance.
There are many ways to support people with hearing loss. Many use hearing aids, cochlear implants, or sign language. Some people also use subtitles or learn lip reading. 

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