What is the difference between conductive hearing loss and sensorineural hearing loss?

What is sensorineural hearing loss?

Sensorineural hearing loss is the most common type of hearing loss. It is a type of permanent hearing loss that occurs when there's damage to the hair-like sensory cells located in the inner ear, known as stereocilia. It can also be defined as damage to the auditory nerve itself, causing a weakening or prevention of nerve signals to the brain. This kind of loss of hearing can affect both ears and affect how sounds are heard and understood - speech sounds can be particularly difficult to pick up. 

The causes of sensorineural hearing loss

Sensorineural hearing loss can be caused by a number of conditions including genetic factors, environmental factors such as noise exposure, and medical conditions such as autoimmune disease, infections and neoplasms. Other reasons include:

• Genetic condition
• Ototoxic drugs (having a toxic effect on the ear or its nerve supply)
• Head traumas
• Different types of illnesses (mumps, meningitis, Ménière's disease)
• Acoustic neuroma
• Various neurological conditions (brain tumour, multiple sclerosis, stroke)
• Malformations in the cochlea
• However, the two most common causes are ageing and exposure to a sudden or continuous loud noise

While age related hearing loss is connected to the natural course of time, noise-induced hearing loss can be avoided if proper measures are taken such as wearing ear protection, e.g. at a loud workplace or rock concert.

The symptoms

The symptoms depend on what part of the cochlea is damaged and the extent of the damage. Some people with sensorineural hearing loss have slight difficulties in certain situations like  having trouble following conversations in loud places, or not being able to hear women's and children's voices well. Other people may have major problems understanding speech or other sounds without special equipment or help from another person. People with sensorineural hearing loss often find it harder to understand speech because background noise very easily masks the softer speech sounds, or they may have ringing in their ears (tinnitus) or dizziness because of the damage to the inner ear. Other symptoms include:

• Trouble understanding conversations in noisy places 
• Ringing in the ears (tinnitus) 
• Being very sensitive to sounds 
• Feeling of fullness in the ear
• Having a harder time understanding women's and children's voices

How to treat sensorineural hearing loss

The damaged hair-like cells of the inner ear and auditory nerve cannot currently be repaired with medical or surgical repair methods. However, sensorineural hearing loss can still be managed through the use of hearing aids or cochlear implants depending on how severe the level of hearing loss is. 

If the loss is mild, amplification may allow an individual to hear almost normally again. If it is moderate or severe, the person might still be able to take advantage of other assistive listening devices that can amplify sounds, such as amplified corded phones and wireless TV listeners. Assistive listening devices include a wide range of either stand alone products such as amplified phones, as well devices that can be added to hearing aids to further enhance the amplification benefit. If the loss is profound, a cochlear implant may be recommended. Cochlear implants are  surgically placed in the inner ear to provide a sense of sound.

What is conductive hearing loss?

Conductive hearing loss is a less common type of hearing loss and occurs when sound waves are unable to travel through the outer ear canal and middle ear to the inner ear. This could be some kind of obstruction in the external auditory meatus (ear canal), which means that your eardrum does not vibrate properly in response to sound or some blockage or other issue in the middle ear. The end result is that the full sound level is prevented from getting to the inner ear. Conductive hearing loss can either be temporary or permanent depending on how it is caused. 

The causes of conductive hearing loss

Conductive hearing loss is caused by the external or middle ear not conducting sound properly. The following are common causes of conductive hearing loss: 

• Earwax blocking the outer ear canal 
• A foreign object in the outer ear canal 
• Cholesteatomas, benign tumors in the middle ear
• Otitis media, an infection in the middle ear 
• Scarred tissue from a trauma to the head or neck area which covers part of the eardrum and/or bones of hearing 
• Damage to one or both tiny bones of hearing (the ossicles) that transmit sound vibrations from the eardrum, through the semicircular canal and to the cochlea 
• Ear fluid in the middle ear
• Perforation of the eardrum (tympanic membrane)
• Otosclerosis (a hereditary disorder causing progressive deafness due to overgrowth of bone in the inner ear)
• Head injuries

The symptoms

The symptoms of conductive hearing loss are very specific to the specific hearing loss that is occurring. Typically, conductive hearing loss refers to problems in the outer or middle ear, causing a reduction in the ability to hear at a normal hearing level. This issue can be related to fluid in the ear, a foreign object lodged in the ear canal, ruptured eardrum, impacted wax preventing waves from entering the inner ear organ, otosclerosis (a condition where your ossicles are stuck together), or even benign tumors. A person will experience symptoms of conductive hearing loss when there are problems with sound reaching their cochlea. 

Typical symptoms include: 

• Difficulty hearing out of one ear
• Ear pain, itching, discomfort, or other unusual sensations in one or both ears
• A feeling of pressure within one or both ears
• Difficulty understanding the speech of others (especially when background noise is present e.g. telephone calls)
• Sensing that your own voice feels louder

How to treat conductive hearing loss

There are some medical or surgical treatments that may be used to treat conductive hearing loss caused by wax impaction, foreign objects, abnormal growths or ear infections. Treatments also include antibiotic ear drops or ointments, surgical procedures such as Tympanoplasty or the extraction of earwax. 

Conductive hearing loss can be treated with the use of hearing aids. The type of device used as a treatment option for conductive hearing loss is determined by an audiologist after a complete hearing assessment. The type of hearing aid fitted will depend on the level of conductive hearing loss, and other factors specific to each person. For example a behind-the-ear aid may be required if the ear canal has been damaged. 

Mixed Hearing Loss

Sometimes it's not a case of Conductive vs Sensorineural Hearing Loss, but a case of Mixed Hearing Loss. If someone shows both sensorineural and conductive hearing loss, it can be classed as mixed hearing loss.

Mixed hearing loss can result from a combination of any of the causes of sensori-neural and conductive hearing losses. For example one could see wax blockage alongside a noise induced hearing loss. Management of mixed loss depends therefore on the cause of each part of the hearing loss.  

Hearing Test

It's worth testing your hearing regularly and at HearingDirect, we have created our very own online hearing test. It's completely free and you can do it in the comfort of your own home.

All you will need is a few free minutes and some ear or headphones. Once the hearing check is complete, you will get your results instantly and based on the outcome of the hearing test, you may be encouraged to take further action.

If you have sudden hearing loss for any reason, do seek help immediately.

Further Reading

You may find these articles of further interest:

• Guide to Hearing
• What is Sensorineural Hearing Loss? Causes, Symptoms and Treatment
• What is Conductive Hearing Loss? Causes, Symptoms and Treatment
• Tips for Unblocking your Ears
• Age Related Hearing Loss: Causes, Symptoms and Management

About Hearing Direct

We are one of the world's leading hearing aid specialists. HearingDirect offers a wide range of affordable products, and information resources to help improve the quality of life for the hard of hearing. We sell:

• Hearing aids,
• Batteries,
• Accessories such as earplugs,
• and amplified devices such as super loud alarm clocks and amplified phones.

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Author: Joan McKechnie

After qualifying as a Speech-Language Pathologist and Audiologist Joan has spent most of her 20 year career in hearing-care related roles. She has a wealth of experience within the hearing aid and hearing rehabilitation fields and has worked in manufacturing environments with two hearing aid companies helping to develop products and roll out new technologies. Joan has been involved with Hearing Direct since its launch and enjoys the online retail environment which seeks to provide easier access to hearing products and accessories. She is HCPC registered. Read Joan's full bio here.