|Hearing loss is a reduced ability to hear, and it can range from a mild loss (25-40 decibels), that causes a difficulty hearing whispers, to a moderate loss (41-55 decibels), that causes a difficulty hearing normal speech, a moderately severe loss (56-70 decibels), with the ability to hear loud speech, a severe loss (71-90 decibels), with the ability to hear loud speech very close to their ear, or a profound loss (>90 decibels), leading to deafness and the inability to even hear speech that is amplified.
There are two main types of hearing loss in children, conductive and sensorineural, but you can also have a mix of the two. A conductive loss is the most common cause of hearing loss in children and can be caused by conditions associated with the external ear or the middle ear that block the transmission of sound, such as with an ear infection (otitis media), fluid in the ear (otitis media with effusion), impacted ear wax (cerumen), a perforated ear drum, otosclerosis, a foreign body in the ear canal (such as a bead), a cholesteatoma, or birth defects, such as those that cause a small or absent ear canal. Many forms of conductive hearing losses can be treated with surgery. On testing, a conductive loss will produce a flat audiogram.
A sensorineural loss or 'nerve deafness' is caused by conditions associated with the inner ear or central auditory pathways of the brain. It can develop prenatally, be present from birth or can develop later, and is most commonly caused by congenital infections (CMV, rubella, herpes, syphilis, toxoplasmosis), use of ototoxic drugs (such as chemotherapy and certain antibiotics), prematurity with birthweight < 1500g, neonatal illnesses, including jaundice with a bilirubin high enough to warrant treatment with an exchange transfusion, persistent pulmonary hypertension of the newborn associated with mechanical ventilation, and conditions requiring ECMO, heredity (with a family history of permanent childhood hearing loss), bacterial meningitis, head trauma, exposure to loud noises, syndromes associated with hearing loss such as neurofibromatosis, osteopetrosis, and Usher's syndrome, neurodegenerative disorders, such as Hunter syndrome, or sensory motor neuropathies, such as Friedreich's ataxia and Charcot-Marie-Tooth, or as a natural phenomenon of aging (presbycusis). Although there is no cure for most cases of sensorineural loss, children can usually be helped with hearing aids (can be started as early as two months of age), therapy to build and improve communication skills, and preferential seating in schools. For children with more severe loss, cochlear implants may be beneficial. On testing, a sensorineural loss will produce a sloping audiogram, with lesser degrees of hearing loss at lower frequencies and greater degrees of loss at higher frequencies.
Children with any of the above risk factors or conditions associated with hearing loss should have their hearing screened at birth and every six months until age three.
You should see your doctor if you think your child does not hear well. Signs that he may not be hearing normally include not startling to loud noises as a newborn or not meeting his normal speech or language developmental milestones. The early speech and language milestones which are listed below include the upper limit of when 75% of infants meet this milestone, so your child may still be developing normally if he has not mastered a milestone by the age indicated. These milestones should be used as a general guideline to help identify infants that are at risk for having speech and language problems so that their development can be watched closely. You should discuss it with your Pediatrician if your infant is not meeting these milestones on time so that he or she can determine what, if any, interventions need to be made. Developmental language delays, especially if secondary to a hearing loss, should be identified as early as possible.
Early speech and language milestones:
- Newborns can localize a sound to their right or left side shortly after being born and will turn their head or look in the direction of a sound. This works best with loud noises when your baby is awake and alert, but they should also be able to hear soft sounds. They can also begin to smile spontaneously and in response to someone by 1 month. Infants learn to recognize their parents by 1-2 1/2 months.
- Infants can imitate speech sounds by 3-6 months.
- Monosyllabic babbling, or making isolated sounds with vowels and consonants (ba, da, ga, goo, etc) usually begins by 4-8 months.
- Polysyllabic babbling, or repeating vowels and consonants (babababa, lalalalala, etc) usually begins by 5-9 months.
- Comprehending individual words (mommy, daddy, no) usually occurs by 6-10 months.
- By 5-10 months, most infants can say mama/dada nonspecifically, using the words as more than just a label for his parents.
- Many infants can follow a one step command with a gesture (for example, asking for an object and holding your hand out) by 6-9 months. He should be able to follow a one step command without a gesture by 7-11 months.
- The correct use of mama/dada as a label for a parent usually occurs by 7-12 months.
- The first word (other than mama/dada) is usually spoken by 9-14 months.
- By 10-15 months, he should be able to point to an object that he wants.
- Your child will be able to say 4-6 words (other than mama/dada and names of family members or pets) by 11-20 months.
- He should be able to follow a two step command without a gesture by 14-21 months.
- By 16-20 months your child should be able to tell two wants using single words (juice, milk, more, etc.).
- He should be able to point to one or more body parts by 14-18 months, and this will increase to 6 body parts by 22 months.
- Two word combinations or sentences are used by 18-22 months and can include phrases like 'Want milk', 'More juice', etc.
- A vocabulary spurt leading to a 50+ word vocabulary occurs by 16-24 months.
- Pronouns (me, you, etc) are used by 19-26 months, although they may still be used incorrectly (reversed, etc). Most children can use pronouns appropriately by 30 months.
- By 24 months his speech should be half understandable by strangers, or someone who is not routinely around the child.
- By 24-32 months he should be able to name 4 pictures.
- Conversations, with 2-3 simple sentences put together, can usually occur by 26-32 months.
- He should understand two prepositional commands (put the cup on top of the table or next to the book) by 27-34 months.
- By 29-34 months he should be able to give the name and use of at least two objects.
- He should be able to name one color by 2 1/2 - 3 1/4 years, and this will increase to 4 colors by 3 - 4 1/4 years.
- By 3 years his speech should be 75% understandable by strangers, or someone who is not routinely around the child and he should have a vocabulary of about 250 words. His speech should be fully understandable by 4 years of age with a vocabulary of well over 600 words.
Signs that your older child may have difficulty hearing include sitting close to the television with the sound turned up to a loud volume, having difficulty in school, not responding to someone that is talking without being face to face, not being startled by very loud noises, having abnomal speech development, or stating that he is having difficulty hearing.
Children can usually be screened for hearing loss in your Pediatricians office with a simple test (audiometry) after they are cooperative enough (usually after four years of age). Younger children (from birth to age 4) usually need to see an audiologist for more detailed testing, such as an ABR or auditory brainstem response test, or OAEs (otoacoustic emissions), which do not require the child's cooperation.
Many large nurseries are now commonly screening newborns before they leave the hospital, and as more hospitals do this, it should reduce the age at which children with hearing problems are identified and improve their outcome. If you child has failed a newborn hearing screen, then it should be repeated in 1-3 weeks. If he fails again, then he should see a professional audiologist for more formal testing and be referred to an early childhood intervention program.
If you think that your child is not hearing well, if he is at high risk of developing a hearing problem, has school performance problems or if he is not meeting his normal speech or language developmental milestones, then it is very important that his hearing be formally tested by a professional. It is not enough that they think that he hears because he responds to a loud clap or bell in the doctor's office or because he comes when you call him from another room. Parents are usually the first ones to think that there is a problem with their child's hearing, and this parental concern should be enough to initiate furthur evaluation.
Hearing Loss Internet Resources:
- Better Hearing Institute: "a nonprofit organization that informs persons with impaired hearing, their friends and relatives, and the general public about hearing loss and available help through medicine, surgery, amplification and other rehabilitation" and includes a parent's information page 'A Guide to Your Child's Hearing' and a frequently asked question list about people with hearing loss.
- Shockwave: the largest, most sophisticated and up-to-date web page database for audiology, the ear, and hearing loss, on the Planet!
- American Speech-Language Hearing Association (ASHA): "The American Speech-Language Hearing Association (ASHA) is the professional, scientific, and credentialing association for more than 99,000 audiologists, speech-language pathologists, and speech, language, and hearing scientists. ASHA's mission is to ensure that all people with speech, language, and hearing disorders have access to quality services to help them communicate more effectively."
- The American Academy of Audiology - "a professional organization of individuals dedicated to providing quality hearing care to the public. We enhance the ability of our members to achieve career and practice objectives through professional development, education, research and increased public awareness of hearing disorders and audiological services," and includes an Understanding Your Audiogram page that explains hearing test results and web links to other sites.
- The American Society for Deaf Children - "an organization of parents and families that advocates for deaf or hard of hearing children's total quality participation in education, the family and the community."
- National Association of the Deaf (NAD): provides information on programs and activities including grassroots advocacy and empowerment, captioned media, certification of American Sign Language professionals, certification of sign language interpreters, deafness-related information and publications, legal assistance, policy development and research, public awareness, and youth leadership development.
- Cochlear Implant Association, Inc.: a nonprofit organization for cochlear implant recipients, their families, professionals, and other individuals interested in cochlear implants. The Association provides support and information to anyone who has a cochlear implant or a child with an implant, or is interested in information about implants