Understanding Hearing Loss
Posted on 30 November 2020
Communication is a vital function to transmit information in every single living unit, no matter how simple. In an organism of higher complexity, the information necessary for life will be correspondingly more complicated. Humans built a system of symbols to communicate – language. The basic building block for language is sound, but for it to be effective, sounds must be organised into words (phonology and semantics) and then arranged into meaningful sentences (grammar) and eventually be appropriately applied (pragmatics).
What is the role of hearing in speech development?
According to Dr Ludwig de Jager, ENT at Mediclinic Potchefstroom, despite humans having an inborn ability to acquire language, this process remains a complex matter and for it to happen, we must perceive or hear the sound and language being used. This exposure must happen timely as this window of magically mastering a complicated skill, dwindles after the age of 5.
Understanding hearing loss
Dr de Jager explains that hearing loss is not just a health issue but affects how the individual perceives their surroundings and thrives in a ‘hearing world’. The causes for hearing loss are numerous – but it is important to understand the kind of loss a patient suffers from, before knowing the best course of treatment.
For humans to make sense of sound, the sound wave must be converted into an electrical impulse. And that is exactly what the ear has been designed to do. This conversion takes place in the organ of Corti which forms part of the inner ear. From here on the electrical impulse is sent to the brain via the nerve of hearing.
When the ear has difficulty to transform the sound wave to electricity, or sending it to the brain, sensorineural hearing loss results. According to Dr de Jager, “Various conditions could impact or harm the inner ear: genetic issues, infections, excessive noise exposure, certain medications, various disease processes (diabetes, hypertension) as well as the wear and tear associated with aging.”
He continues, “However, for sound to be transformed into an electrical impulse it must first reach the inner ear. When this process fails or is compromised then patients will suffer conductive hearing loss. This could be due to conditions affecting the external canal (impacted wax), the tympanic membrane (perforation or severe scarring), the middle ear (fluid, growths) or the tiny bones in the middle ear space (dislocation, fixation).”
The two conditions can also occur simultaneously, which will account for mixed hearing loss. This division allows us to logically categorize the causes and treatment principles of hearing loss.
From a treatment perspective the rule of thumb is that conditions causing conductive loss can theoretically be treated with medication or surgery. Sensorineural loss, however, usually needs to be compensated for by amplification.
Hearing loss in the child
How does hearing loss present in the child and how do we know?
The symptoms a child with hearing loss present with largely depend on the age of the child and the type and duration of the of the disease complex. Hearing loss in the infant (pre speech and language development – as in congenital hearing loss) is likely to present with delay of development of speech and language. Hearing loss in the older child (during / post acquisitioning of speech and language) could show with stalling in speech development but also with other symptoms: behavioral issues, learning difficulties (school situation) and other symptoms characteristic of the particular disease complex.
Due to every child having his or her own rhythm in terms of development the question arises of how parents and caregivers can identify the child with delayed speech development? As with general motor neurodevelopment (sitting, crawling and walking) milestones in speech and language development have been well formulated. For example: initial cooing goes over in babbling (age 6 months) while actions and gestures are used to communicate. Roughly at 12 months the first word appears, and the vocabulary slowly expands. At 18 to 23 months the child might have mastered 50 words and starts to combine words. At 2 – 3 years the child uses 3 words sentences while spatial concepts are starting to develop, and the child employs descriptive words and plurals. Speech also becomes more accurate. Between 3 and 4 they start to group objects and identify colors and express ideas and feelings. At age 5 they understand time sequences and engage in conversations easily using sentences that can be 8 or more words in length.
Diagnosing hearing loss in the child
“After identification of a child with possible speech and language delay, formal audiological evaluation should be conducted by an audiologist; a process that can be quite challenging,” explains Dr de Jager, “There are many types of hearing tests – some of them can be used on all ages (typically the ‘objective tests’ requiring no input from the patient being tested) while the use of others (’subjective tests’) are based on the child’s age and level of understanding (play audiometry, visual reinforced audiometry and eventually pure tone audiometry).”
But there is a wider safety net: neonatal hearing screening. According to Dr de Jager, “These should be done in the first month after birth and can play a significant role in early identification of infants with hearing loss. And if we consider an incidence of 6 to 19 out of every 1000 newborns in developing countries suffering hearing loss then this becomes a worthwhile investment. The second-best option would be to at least screen the high-risk patients.”
How is hearing loss in the child addressed and managed?
Dr de Jager explains that the type and magnitude of hearing loss will dictate the remedy. Differentiating between conductive and sensorineural hearing loss again becomes the basic guideline. Surgery might be indicated for the conductive group. The procedure might be as simple as draining middle ear fluid or very complex as in total reconstruction of the external and middle ear. Amplification also can be considered in those patients where surgery for whatever reason is not possible.
In the sensorineural group amplification is the mainstay of treatment. As a rule of thumb conventional hearing aids should provide excellent rehabilitation in the patient with mild to severe hearing loss, but once the loss becomes severe to profound, cochlear implantation is preferred.
Speech and language abilities of infants and children with sensorineural hearing impairment can equal that of their hearing peers if the hearing impairment is identified early and intervention commenced timeously.
The advantageous of early diagnosis and treatment of hearing loss, particularly in the infant, are for obvious reasons critical.
The importance of parental support
The diagnosis of hearing loss in a child, and particularly in cases where it is going to be a lifelong sentence, is often traumatic for the parents and the whole family as it indeed becomes a burden affecting all. For this reason, it is mandatory that parents and siblings receive guidance on how to cope with this situation (and the patient). Besides the medical fraternity (physicians / nurses / audiologists / social workers etc.) various groups, both local and national, exist that could support families and assist in developing coping strategies. Groups like THRIVE, The Carel du Toit Centre and the National institute for the Deaf come to mind.
Further reading: Hearing loss in adults