Unit 2: Causes, Prevention and Effects of Deafness
2.1 Causes and prevention of hearing loss
2.2 Effects of Hearing impairment on various domains of development, education and employment
2.3 Hearing loss impacting speech perception
2.4 Early identification and critical period for learning language and hearing
2.5 Developmental milestones of auditory behaviour
2.1 Causes and prevention of hearing loss
Although these factors can be encountered at different periods across the life span, individuals are most susceptible to their effects during critical periods in life.
Prenatal period
Perinatal period
Childhood and adolescence
Adulthood and older age
Factors across the life span
Things that can cause sensorineural hearing loss are:
Things that can cause conductive hearing loss are:
Prevention
Hearing is an important sense for communication. A major part of all learning takes place through hearing. Therefore, a reduction in a person's ability to hear can severely affect his/her life. Hearing loss can be caused by several factors- some which occur even prior to birth, and some which cause hearing loss to set in later. Hearing loss may even be hereditary. But in several cases, hearing loss can be prevented. Here are a few guidelines on how you can protect your hearing:
Do not use sharp objects to clean your ears.
Using pins, pencils, needles and other pointed objects to clean your ear can easily damage the wall of the ear canal, or even the ear drum. This would lead to hearing loss. Wax generally comes out of the ear naturally. If there is any impacted / hard wax or excessive wax secretion, get your ears cleaned by an ENT doctor.
Do not insert any objects into the ear canal
Children may insert seeds, grains, pebbles, soil, etc, into the ear canal during play. In case of adults, insects are the most commonly found foreign bodies. Get help from an ENT doctor immediately. Foreign bodies may block the ear drum or damage the ear drum, causing a mild to moderate hearing loss. Do not pour water into the ear, as it may cause infections.
Wear a helmet
Avoid injuries to your head and ears. Road Traffic Accidents may damage hearing. Any injuries to the head may also cause hearing loss. Wear a helmet to protect yourself from road traffic accidents.
Avoid noise
Be aware of sources of noise. Exposure to loud and excessive noise is one of the most common causes of hearing loss. Protect your ears from the sounds of gunfire, firecrackers, very loud music, etc. If your job requires you to work in a noisy situation (saw-mills, road construction, printing works, factories, etc.), make sure you wear hearing protective devices such as ear muffs or ear plugs, in order to protect your hearing. Your audiologist will be able to help you select an appropriate hearing protective device.
Take good care of health during pregnancy.
Infections such as measles, mumps, syphilis, and rubella during pregnancy may damage the unborn child's hearing. Exposure to radiation / X-rays, drug intake during pregnancy, falls and injuries can also affect the child's hearing. Pregnant women should meet their doctors regularly for advice on diet, general health and vaccines. This is needed to protect the unborn child from all health problems, including hearing loss. Rh-incompatibility can also affect the child's hearing. This condition occurs if the mother's blood group is ve and the child's blood group is +ve(for example, if the mother's blood group is B and the child's blood group is B+).
Prevent ear infection.
While feeding your baby, hold him/her in a slanting position. This can prevent the baby from having ear infections. Do not pour hot oil or any other liquids into the ear, as it may result in pain and ear discharge. If you swim or dive, use ear plugs to keep the water from entering your ears. Dirty water in the ear might cause infections, too. While blowing your nose, do so gently and from both nostrils. Otherwise, fluids from the nose may be forced into the middle part of the ear, Thus causing infections.
Get immunizations done on time.
Diseases like mumps, measles, rubella, encephalitis, meningitis, typhoid, etc. may affect hearing. As far as possible, prevent these diseases and get children vaccinated on time. If you get these diseases, you must get advice from a qualified audiologist.
Do not take medicines indiscriminately.
Certain antibiotics (like streptomycin, kanamycin gentamycin) and aspirin may cause hearing loss. If you have to take any of these drugs for a prolonged duration, have your hearing evaluated periodically. If you think your hearing is being affected, talk to your doctor. Check if the dosage can be lowered, or if you can take an alternate medicine.
Discourage marriage between close relatives.
Consanguineous marriages, or marriages among blood relatives, increase the chances of children being born with hearing loss.
Do not neglect earaches or ear discharge.
Ear infections, if not treated, can cause hearing loss. Consult your ENT doctor immediately if you have any of the following symptoms: Ear pain Fluid in the ear Itching sensation Ringing in the ear
2.2 Effects of Hearing impairment on various domains of development, education and employment
a) On language and communication
Hearing loss can affect a child s development of speech and language skills. When a child has difficulty hearing, the areas of the brain used for communication may not develop appropriately. This makes understanding and talking very difficult.
When hearing loss is identified early and managed appropriately, the child can become an effective communicator. This process involves caregivers and professionals working together.
Most hearing loss is identified through a screening at birth. Some children are not diagnosed until later, when speech or language skills are not progressing. Earlier identification and management of hearing loss results in better outcomes for the child.
Words
Children with hearing loss do not learn words as fast as those who have normal hearing. They may:
Children with hearing loss may have trouble understanding and using sentences. They may:
Children with hearing loss cannot hear sounds well. They may have problems speaking clearly. They may:
Children with hearing loss have trouble in school. Reading and math may be the hardest for them. Some facts about hearing loss and school success include:
b) On cognitive functioning
The interaction between a person and his or her surrounding environment is mediated through sensory experiences. The sense of hearing, in particular, fundamentally facilitates communication and fosters social interaction. Hearing is the key to learning spoken language and is important for the cognitive development of children. Without suitable interventions, hearing loss is a barrier to both education and social integration.
Cognitive abilities like language, memory, reasoning, visualization, and perceptual functioning shape human action and are considered critical to the successful interaction with the environment. Alternatively, hearing loss can disrupt a child s ability to communicate, and negatively impact cognitive development.
According to Tonietto et al, subcortical development occurs during the first 3 months of life, which allows infants to suckle and sleep. Even in this early stage, it is the mother's responsibility to identify the child's desires and anxieties by, as Virole indicates, symbolizing and giving meaning, providing answers and nurturing. Such symbolizations will allow the child to recognize the objects in the world. Furthermore, Tonietto et al, Carpenter et al, and Tomasello point out that by the age of 9 or 10 months, cortical activity increases, allowing the child to have shared attention, which is important for behavior regulation. The child displays mirror behavior, as he or she is able to imitate gestures and show interest in the surrounding objects and environment. The child is capable of pointing to objects that call for his or her attention and following adults' pointing gestures. Baron-Cohen put forth that the absence of these characteristics indicates a developmental delay, a specific language delay, or a more serious condition such as autism, in which the absence of symbolic games is observed. In addition to the desire of communicating, understanding other people's intentions is a prerequisite for language development.
c) On academic achievement
Untreated hearing loss can have a significant impact on a student s education. It can lead to difficulties in understanding and processing spoken language, which can affect their ability to follow classroom instructions, participate in discussions, and comprehend lectures. This, in turn, can lead to academic struggles, reduced motivation, and even social isolation.
Hearing loss can have a detrimental effect on school performance, leading to poor grades, missed assignments, and difficulty remembering information due to the challenge of understanding what is being said in class.
d) On social personal development
Students with hearing loss often have difficulty engaging in conversations and socializing, which can lead to feelings of isolation from their peers. It also makes it difficult for them to form relationships or comprehend group discussions. This impairment can create a serious obstacle between these students and the full academic experience that they deserve.
For students with hearing loss, their impairment can often cause emotional turmoil, such as anxiety, depression, and a diminished sense of self-esteem. This distress is frequently the result of struggles in schoolwork or social interactions making everyday life more demanding than it already may be.
Hearing impairment can negatively affect interpersonal communication, intimate relationships, access to education, employment opportunities and economic independence.
The emotional impacts of hearing loss can be far reaching. They can cause feelings of distress, frustration, anger, embarrassment, inferiority, shame, loss of identity, rejection, and loneliness (Bennett et al., 2021). People with hearing loss tend to develop both helpful and unhelpful social behaviours in an attempt to cope with the hearing loss and associated emotional distress in social situations. These may include avoiding situations such as not attending social events, or staying silent in group conversations (often referred to as tuning out ).
The breakdown of communication that is often experienced due to hearing loss can affect an individual s ability to socially engage. Consequently, untreated hearing loss can lead to reduced social activity, social isolation, lower levels of self-esteem, loneliness, and reduced quality of life.
e) On vocational training and employment
It is really true that vocational training opens the door of need-based education for the students with hearing impairment. It develops the professional skills and efficiencies of students with hearing impairment. It also enhances their other associate skills and power of self-evaluation providing theoretical information with practical work. Vocational Training is a comprehensive term embracing those aspects of the special educational process involving in addition to activities, the study of various trades and related subjects including the acquisition of practical skills, attitudes, understandings and knowledge related to vocations.
The aim of vocational training programme is to offer the
Hearing-impaired employed opportunities for training and work experience that will improve their prospects of obtaining a satisfactory permanent job and providing a constructive alternative to unemployment. Job placement process enables hearing impaired to successfully prepare for and to keep jobs that they want. The predominant objective for most young handicapped people is to get a job. Limited occupational knowledge, available work opportunities, and academic success seemed to be strongest factors affecting job placement of handicapped students. One serious
problem for deaf persons is the reduced number of unskilled and semi-skilled jobs available today (Joiner, et al, 1968). The changes in the job market demands a need for increased occupational opportunity awareness among deaf students.
Hearing loss can subtly influence various aspects of your life, including your career. In our interconnected world, where communication is key, especially in professional settings, untreated hearing loss can pose unseen challenges that may affect job performance and career growth. Office chatter, meeting details or even simple instructions from a colleague might become harder to comprehend.
Hearing loss s impact in the workplace is more substantial than you might realize. It s not just about struggling to hear instructions or missing crucial information during meetings. It also influences how you interact with your colleagues, which can affect your overall job performance and satisfaction.
Here are some ways that hearing loss can affect your work life:
Our workdays are filled with moments of camaraderie, often centered around the water cooler, where our ability to hear and engage becomes essential. Imagine missing out on the office banter or struggling to participate in a lively discussion with colleagues.
It s not just about catching the spoken words but also grasping the nuances and subtle cues that enhance our workplace interactions. The correlation between hearing and workplace camaraderie is profound, influencing the quality of our professional relationships and how we engage with our coworkers. Recognizing this connection empowers you to navigate social interactions seamlessly, even when dealing with hearing loss.
Factors influencing achievements
In India, schools and colleges follow general conventional teaching methodologies to teach students with deafness. The lack of expertise in pedagogy adds to the barriers faced by students with deafness receiving effective educational services. Prior academic achievements, student background attributes, and eLearning attributes are considered as the factors that affect the academics of a student. For a student with hearing impairment, the attributes related to hearing impairment may also need to be considered. The identification of these characteristics that influence students with hearing impairments' academic performance may aid educational stakeholders in developing tailored and individualized teaching plans for them, as well as policies that will enable them to pursue higher education possibilities. Additional accommodations are required for including students with hearing impairment in mainstream schools. The identification of characteristics that influence students with hearing impairments' academic progress may aid in the identification of such adjustments.
In the case of a student with hearing impairment, one of the major barriers he faces throughout his life is the communication barrier. Sign language is considered as his mother tongue and recent studies show that bilingual education that is written language through sign language is very effective in the education of students with hearing impairment.
All teachers do not know how to modify instructional materials in order to meet the particular needs of HI pupils in their classrooms. HI teachers consider that customization of teaching and learning materials is the duty of HI experts. Furthermore, lack of teaching and learning materials in inclusive classes has revealed a substantial gap between the demands of HI pupils and what these teachers now accomplish in inclusive classrooms. This circumstance makes the quality of schooling for these HI pupils questionable. Overcrowding is one of the major difficulties that most of our inclusive school s face. This is because it affects even the teacher's capacity to reach all pupils when they require a tailored curriculum due to lack of space. Due to overpopulation and a lack of space, most learners with HI are disregarded. It is critical that all pupils are accommodated in teaching-learning environments.
Poor sitting arrangement, poor position of a teacher from pupils, absence of noise reduction device inside the classroom, poor location of the class, and overcrowded classrooms were also identified as factors for low academic performance among HI pupils.
To ensure the quality provision of inclusive education, education practitioners and policymakers should revise the policies about inclusive education, along with supporting the learners with the required facilities and a good learning environment.
2.3 Hearing loss impacting speech perception
According to experts, hearing loss is a progressive condition that can affect speech if left untreated. The truth is these speech interferences affect both parties engaged in a conversation. In other words, the person with hearing loss and the other individual listening will experience difficulty expressing or understanding some words.
Decreased Speech Perception is most likely the most significant part of it all. A reduction in speech comprehension takes a toll on social interactions. In other words, the difficulty in hearing and the ripple effects on your ability to communicate correctly make you lose interest in conversations. Furthermore, decreased speech perception involves an inability to put emotions in your words. This is because you are already straining to sound audible, which gives way to a possible loss of emotions in your speech.
People with sensorineural hearing loss have difficulty understanding speech, especially when background sounds are present. A reduction in the ability to resolve the frequency components of complex sounds is one factor contributing to this difficulty.
Normal-hearing people get a considerable benefit from temporal dips in background sounds, but the hearing impaired seem to have little or no ability to listen in the dips to enhance speech perception, even when appropriate amplification is provided to ensure that the sounds in the dips are above the absolute threshold.
Understanding speech requires anatomical and functional integrity of the peripheral and central auditory system and an acoustically appropriate communication context. However, noise is present in most communication situations, which may decrease the probability of acoustic information being available. Agnew has suggested that the term noise is generic, and encompasses several situations comprising different speech understanding problems, as there are different types of noise.
Noise affects understanding of speech in every person. This issue is compounded in patients with hearing loss when speech and noise compete at the same time. Loss of acoustic information is compensated by other non-auditory cues during silence. Noise may be compensated by controlling its environmental intensity or by using strategies such as directional microphones and acoustic filters in personal sound amplification products (PSAPs), which may improve speech understanding.
Speech perception in hearing-impaired listeners can be adversely affected by various factors including the type of hearing aid signal processing, environmental limitations, and individual differences in the peripheral auditory physiology and higher-level cognitive processes. These factors together influence which aspects of the speech signal are potentially informative and beneficial for the hearing-impaired listener.
2.4 Early identification and critical period for learning language and hearing
Early childhood (0-6 yrs) is a time of remarkable brain development. It is the critical period that determine a Persons s ability to reach her/his lifelong health, social and economic potential. Providing quality early childhood intervention early in a child s life supports them to develop the skills needed to enable him to lead an independent and dignified life. Early Intervention provides specialized support and services for infants and young children at risk or with disability and/or development delay and their families to help their development, well-being and participation in family and community life. Significant hearing loss is one of the most common major abnormalities present at birth. If undetected, it will impede speech, language and cognitive development.
Identifying hearing loss at a very early age is important because children with hearing loss often fall behind their peers in speech and language development, cognitive skills and social skills. If the hearing loss isn t treated these deficits can lead to adult issues such as reduced socio-economic status, poor socialization skills, depression, etc. Obviously, the earlier we can identify hearing loss the sooner we can begin with the intervention for the better outcomes of that individual.
Early intervention is a type of clinical support and services provided to babies and young children with developmental disabilities and delays. In the case of hearing loss, early intervention is a strategy that therapists will employ to reduce the effect of hearing loss on a kid.
Especially, with early detection and intervention for hearing loss, the quality of life of a person can be improved. Furthermore, the earlier it is detected, the easier it can be for the family, as you will have faster access to the services and information you require to effectively nurture and assist your child.
BENEFITS OF EARLY DETECTION OF HEARING LOSS AND APPROPRIATE INTERVENTION
The child can undergo intervention before the age of six months.
The child will achieve better speech and language and educational success.
The cause of hearing loss can be identified early and managed appropriately.
Associated medical conditions can be identified and managed early.
The child s auditory system will develop better.
The burden of stress within the family will be reduced.
Parents can be offered genetic counselling (if relevant), especially if they are planning for more children.
The child will continue reaping benefits in the long term: social, psychological, educational and professional.
When people hear the words early detection they think it means screening at a young age, but a hearing loss can occur at any age. It is about detecting the problem at the earliest possible time. The sooner you can detect hearing loss, the better the outcome for the person with the loss. Hearing loss can occur at any age and hearing screening plays a vital role to ensure that patients can avoid communication roadblocks and potentially have a better quality of life.
The emerging research suggests: 1) there are sensitive periods when the brain is more susceptible to environmental inputs; 2) early experiences can have enduring effects; but 3) the effects are amenable to change. The concept of critical periods developmental stages when certain experiences are essential for normal development, and failure to obtain these experiences can lead to permanent alterations in brain development and behavior, has been replaced with the concept of sensitive periods developmental stages when certain experiences exert greater influence on brain development and behavior, but brain development and behavior continue to be malleable.
Several types of sensitive periods have been observed:
periods when experience is required for the development of a particular skill (sensitive periods for development);
periods where the system is vulnerable by manipulation of experience like monocular deprivation (sensitive periods for damage);
periods when therapy (compensation of a deficit) is only partially possible after some age has been missed (sensitive periods for recovery);
a distinct type of sensitive periods has to be additionally differentiated: periods for recovery from total deprivation. Complete sensory deprivation from birth leaves the sensory system functionally naive , which is distinct from abnormal juvenile experience (like monocular deprivation or strabismus). It leaves the deprived sensory system functionally incompetent to perform its function in controlling behavior, which differs from consequences of abnormal experience. In abnormal experience, the manipulated sensory system is still used to control the behavior, but is subject to abnormal input. The naive state opens the possibility for cross-modal reorganization, degenerative processes (functional and morphological) and other processes that do not take place if the system remains functional (albeit with abnormal input).
Some auditory functions show optimal performance if learned early in life: e.g. musical experience has most pronounced effects on performance during early childhood (reviewed in Penhune, 2011). Also language learning is easiest early in life. In fact, the best known auditory examples of critical periods were observed in language development (review in Kuhl, 2010, Friederici, 2012). Young children are able to discriminate phonetic contrasts of all languages, however, they specialize in mother language with increasing age and lose the ability to discriminate phonetic contrasts that do not exist in their mother language at around 8th 10th month after birth. This has been observed for many languages (Werker and Tees, 1992). Consequently, the newborn brain is initially very sensitive to acoustic differences. With time, it specializes and remains sensitive only to so-called distinctive features of phonemes in their mother language. Non-distinctive acoustic differences are ignored (abstracted from)1.
This is an excellent example how the brain establishes the world of auditory categories (objects). The brain aims to withstand the enormous variability of the physical world. It gains the ability to identify sounds that belong to the same class of events in the physical world, and learns to ignore their insignificant variability. This increases the robustness of perception. If the acoustic input is e.g. affected by several concurring sound sources, even though some features of the objects are masked, the object of interest remains discernible because some of its other distinctive features are less affected. A side-effect of the appearance of auditory objects is the loss in sensitivity to contrasts that do not contribute to the discrimination of the objects in the given world of experiences. It has to be kept in mind that several objects may in combination constitute another object: phonemes are objects themselves, but they combine into words that are objects on their own. Which object level is appropriate in the given condition may depend on the behavioral context.
The presence of hearing loss at critical periods of language development causes disorders in speech acoustic processing and language synthetics syntax representation and results in defects in language acquisition and synthetics-syntax usage. Language learning in hearing-impaired children requires the presence of natural conditions; therefore, their lingual environment must be the same as for normal-hearing children. Most synthetic and syntax abilities are learned at critical periods of language development, and this is affected by different variables such as the mother s speech, the complexity of heard sentences and repetition communicative situations. Despite making progress in reducing the age of identification/intervention in hearing-impaired children, language development gaps between normal-hearing and hearing-impaired children still exist. Decreasing these gaps will allow more opportunities for evaluating the lingual abilities and rehabilitation program planning of hearing-impaired children based on their needs and abilities.
Early childhood
is a critical period for auditory, language, and cognitive development, and
early identification of permanent hearing loss provides the opportunity for
children to receive appropriate and timely intervention and educational
services. When children are identified late, they are at increased risk of
permanent speech, language, and educational delays.
2.5 Developmental milestones of auditory behaviour
The auditory system is complete and functional at birth but myelination continues for several years in the higher auditory pathways. Auditory development in the fetus and infant entails the structural parts of the ears that develop in the first 20 weeks of gestation (5 months) and the neurosensory part of the auditory system develops primarily after 20 weeks gestational age. The auditory system becomes functional at around 25 week s gestation (5 months).
The cochlea of the middle ear and the auditory cortex in the temporal lobe are most important in the development of the auditory system. They are easily affected by the environment and care practices in the new-born intensive care unit (NICU).
Although auditory development is thought to begin in the third trimester of a pregnancy, not until after birth is an infant exposed to the full range of sound due to the filtering effect of the mother s body. After birth, a newborn does not hear at the same level (0-20 dBHL) as adults (Tharpe & Ashmead) and is less aware of frequency changes, especially in higher frequency sounds. This means that speech will not be heard clearly for an infant in the first six months of life.
The period from 25 week s gestation to 5 to 6 months of age is most critical to the development of the neurosensory part of the auditory system. This is the time when the hair cells of the cochlea, the axons of the auditory nerve, and the neurons of the temporal lobe auditory cortex are tuned to receive signals of specific frequencies and intensities.
Unlike the visual system, the auditory system requires outside auditory stimulation. This needs to include speech, music, and meaningful sounds from the environment. The preterm as well as the term infant cannot recognize or discriminate meaningful sounds with background noise levels greater than 60 dB. The more intense the background noise, especially low frequency, the fewer specific frequencies (pitch) can be heard and used to tune the hair cells of the cochlea. Continuous exposure to loud background noise in the NICU or home will interfere with auditory development and especially frequency discrimination.
The initial stimulation of the auditory system (speech and music) needs to occur in utero or in the NICU to develop tonotopic columns in the auditory cortex and to have the critical tuning of the hair cells of the cochlea occur. The control of outside noise, the exposure to meaningful speech sounds and music, and the protection of sleep and sleep cycles, especially rapid eye movement sleep, are essential for healthy auditory development. The environment and care practices for the fetus in utero or the infant in the NICU are critical factors in the development of the auditory system.
Development of Auditory Behaviour in Infants
|
Infant s age |
Response |
|
At birth |
Arousal from sleep for 90dB SPL |
|
3-4 months |
Rudimentary head turn for normal conversation (50-60 dB SPL) |
|
4-7 months |
Localization to side for soft sounds (40-50 dB SPL) |
|
7-9 months |
Localizes to side and in-directly below for a loud whisper (30-40 dB SPL) |
|
9-13 months |
Localizes to side and below for a loud whisper (30-40 dB SPL) |
|
13-16 months |
Localizes to side, below and indirectly above to soft sounds |
|
16-21 months |
Localizes directly to the side, below and above to a whisper |
|
21-24 months |
Locates directly a sound at any angle to soft sounds |
By 8 or 9 years of age, a typically developing child s hearing level and ability to hear phonemes in a variety of environments are similar to that of adults.
At 12 years of age, however, children can demonstrate poorer speech perception than adults. (Hazan & Barrett)
|
Developmental Milestones for Listening Adapted from Cole & Flexler and Owens |
|
|
Age |
Auditory Milestones |
|
by 4 months |
|
|
by 7 months |
|
|
by 12 months |
|
|
by 24 months |
|
|
by 36 months |
|
|
by 4 years |
|
|
by 7 years |
|
Remember, in some children the hearing loss may also be accompanied by other deformities, such as cleft lip & palate (opening in the roof of the mouth), low set ears, absence of outer ear etc. Some children may not be able to give age appropriate responses to sounds due to other problems such as delayed motor milestones.