Health is a state of complete physical, mental, spiritual, and social well-being, not just the absence of disease or weakness.1 The way one appears, feels, acts, and performs is influenced by one’s well-being. It also impacts our mindset and capacity to handle interpersonal relationships. Mental health refers to our emotional, psychological, and social well-being. According to the World Health Organization (WHO), mental health is a condition of well-being in which a person recognises his or her abilities, can manage typical life challenges, work creatively and fruitfully, and contribute to community.2 How one deals with stress, communicates with others, and makes prudent decisions are all influenced by our mental health. Spiritual health is the connection with a superior existence, oneself, society, and nature, and it includes those aspects of health or human existence that cannot be explained by physical, mental, or social factors, such as a purposeful life, transcendence, and actualisation of various dimensions and capacities of human beings. Positive mental health is defined as the presence of happy feelings and normal functioning (in both individual and social environments). Personal factors such as lifestyle and self-esteem, as well as the physical environment, such as one’s environment or the quality of one’s surroundings; the quality of one’s interpersonal relationships with family, friends, and the community; and the social environment all have a significant impact on mental health. As the popular saying goes, there can be no health without mental health. One’s psychological health has a significant impact on our physical health. Similar to improving the immune system of physical health, practices that promote positive mental health are considered crucial in maintaining good psychological health.
To enhance positive mental health, one should have healthy, meaningful relationships with friends and family; be physically active and maintain a balanced diet; engage in meaningful activities; have a sense of gratitude, empathy, and contentment; have emotions in control and have a right balance of physical activities; and, most importantly, indulge in activities that can enhance resilience. This may range from good psychological health to physical and spiritual health. Music, as not just a cultural phenomenon but as a biological phenomenon, has the power to impact all these realms of health.
Music as a socio-cultural phenomenon binds people to society and culture. It stands as an identity of a given culture. Humans indulge in music, produce music, and are influenced by music in tremendous ways. Music can help improve cognitive functions, emotion regulation, task endurance, and mood; reduce anxiety and depression; stave off fatigue; and improve pain response. Passive music listening often plays an integral part in other daily activities such as physical workout, walking, driving, or other routine day-to-day activities and, most importantly, to kill boredom. For age immemorial, musical activities, musical engagements have been interwoven with several socio-cultural and religious activities across cultures.
This chapter provides an insight into how music permeates several aspects of our functioning and how music positively impacts one’s physical and mental health.
Learning Objectives
• Music’s role in the promotion of mental health
• Music and its association with mental health and brain physiology
• Neuroscience underpinning the music-related brain plasticity
• Neurochemical participation in music production and listening.
Music is not only enjoyable but also beneficial to overall health. Indulging in music, either actively, by singing or playing an instrument, or passively, by listening to music, is known to impact the socio-emotional development across one’s lifespan. This impact includes mood regulation, development of cognitive-emotional skills, socialization ability, personal and cultural identity and overall development of personality. Music has a wide-ranging and profound psychological impact. Music, among other things, can aid in the development of positive mental health by reducing anxiety and stress, facilitating emotion regulation, and improving neurocognitive functions, such as attention, memory,3 mood, and motivation. Music-based interventions have been demonstrated to benefit patients with a range of clinical conditions such as stroke, headaches and migraines, pain management, Parkinson’s disease, and dementia, among other neurological illnesses.4 Music helps in the management of pain and often acts as a powerful method of distraction; recent scientific research has provided evidence as to how music helps in the release of natural pain killers – the endorphins – in the body. There are several examples of how music plays a very important role in our daily lives. Music often evokes feelings that help us connect as social beings, uplifts our thoughts, encourages us and leads us to greater mental health, reflecting in our improved physical and mental performance. There is a strong body of scientific literature demonstrating the association between music engagement and quality of life, well-being, prosocial behavior, social connectedness, and emotional competence.
It is widely acknowledged that both listening to and creating music can have a favourable impact on one’s mood and mental health. Music is both intellectually and physically stimulating, and it boosts psychological well-being. The brain engages a host of higher neurocognitive functions in order to process and comprehend music. Music can help with health and well-being by stabilising or optimising emotions. Various forms of music therapy have shown beneficial effects in various clinical conditions. Music can help people process emotions, trauma, and grief, as well as relax and regulate anxiety and dysregulation. Incorporating music into one’s daily routine can help improve mood and motivation, relax, and improve the brain’s processing efficiency. There are several ways to use music for mental health in day-to-day life.
Classical music is an excellent aid to concentration. Music at a pace of 60 bpm (beats per minute) improves the brain’s ability to process information. Background music, or music played while the listener is primarily focused on another activity, has been shown to increase learning and memory in older adults, according to research. Listening to more upbeat music improves processing speed, while listening to both upbeat and downbeat music improves memory.5 Instrumental recordings in the background, rather than intricate lyrics, which can be distracting at times, can be quite good for concentration and cognitive performance.
Scholars prefer to listen to their favourite music as a pleasant distraction while concentrating on their work. Music-naïve or musically untrained persons benefit from it more than trained professionals in terms of memory enhancement. Trained professionals are more concerned with grasping the music, but the naïve person appreciates the music’s positivity and finds that it does not interfere with the production of new memories. In comparison to rhythmic speaking of sentences, singing new words out loud aids in the learning of new languages.6
Emotion regulation is an intrinsic process that allows a person to maintain a relaxed level of arousal by adjusting one or more characteristics of emotion. Emotion regulation issues can have a long-term impact on a person’s mental health and well-being.7 Many experts believe that appropriate emotion regulation is a sign of mental health since it allows a person to respond and react to events and periods of discomfort in a variety of ways. Music can help people express themselves more effectively. Producing music can help express and process emotions. Few options for producing music are writing lyrics or playing music on an instrument. Music is not about how it sounds but about how it makes one feel. The effect of music also varies according to one’s level of involvement in understanding it. Music, therefore, may be defined as a form of auditory communication between the producer and the receiver. There are other forms of auditory communication, such as speech, but the difference is that music is more universal and evokes emotion. It is also relative and subjective. Listeners perceive the music depending on the surroundings, state of mind, mood, and understanding of its content and not only lyrics. An active listener indulges in music and tries to appreciate the musical choices and the lyrics. Sometimes, a passive listener may also use music as a background activity while focussing on some other activity or task at hand.
Music has the power to alleviate feelings of loneliness and isolation. Whether it is sharing playlists with friends or meeting new individuals, music pulls people with similar cultural and social tastes together and aids in forming bonds. Research suggests that music-based mental health treatments may help health by providing benefits historically linked with exposure to and engagement in arts, such as increased social connectivity.8
Music can help one unwind and cope with stress. The right music helps one relax by resonating with the brain’s alpha frequencies. Hypertension, headaches, and migraines can all benefit from meditation music that focuses on relaxing brain frequencies. Low-frequency music has a unique influence on the autonomic nervous system, which aids in stress reduction.9
Optimism and positive feelings are strongly linked to good mental health. Uplifting and joyful music played loudly can help one get through a terrible day. The upbeat musical tones and lyrics lifts spirits and prepares one for upcoming challenges. Upbeat, fast-paced music gets the mind and body moving, energising and motivating one to embrace what is ahead.10 According to studies, classical and ambient music have the best mood-boosting properties, whereas metal and hard electronic music have the opposite impact.
Music can be quite beneficial in the treatment of pain. One research of fibromyalgia patients revealed that listening to music for one hour a day reduced pain significantly compared to a control group.11 As a result of these findings, music therapy may be a useful aid in the treatment of chronic pain. The researchers also discovered that listening to music before surgery improved outcomes. Additionally, music listeners use less medication to control their pain. When patients were permitted to choose their own music, there was a slight, but not statistically significant, improvement in pain management results.
Music has the potential to be a non-pharmacological treatment for sleep problems. For those suffering from sleeplessness, listening to relaxing classical ragas can be a safe, effective, and economical solution.12 Music influences the stress hormone cortisol, which improves the quality of sleep. For non-pharmacological treatments, the subject’s positive expectations and belief in the treatment method are always key requirements.
Music makes people happier, increases arousal, and boosts self-awareness. The secret to improving one’s mood is to listen to positive, upbeat music.13 Music therapy can be a safe and effective treatment for depression and anxiety in patients suffering from neurological conditions such as stroke, dementia, Parkinson’s disease, and so forth. The type of music one listens to plays a big role in this. Classical and meditative music have the most positive effects on mood, whereas heavy metal and techno music are ineffectual and even detrimental.
Music has the power to improve performance. People can be inspired by the addition of a powerful, rhythmic beat, such as a fast-paced musical track.14 Athletes who listen to music are more motivated and have more endurance. A tempo of between 125 and 140 beats per minute is great for working out. Music can assist in shifting attention away from the intensity induced by physical activity, allowing the person to continue working hard in the gym without feeling tired, muscle soreness, sweating, or increased breathing.
When one listens to or composes music, it stimulates their brain’s creative thinking. Experimenting with various forms of music can help one find a way to flourish at a creative endeavour while also improving their mood. Music from the past does not challenge the brain in the same way as novel music. The unfamiliarity causes the brain to work hard to absorb the new sound, even if it may not seem pleasant at first.
Engaging with music passively or actively requires components of cognitive and affective processing. Music is considered a form of language and is a powerful medium of communication. The core of any human interaction is empathy. It requires both cognitive and affective aspects which enable individuals to recognise the emotional and mental states of others and respond appropriately to the given situation. Empathy is important as it allows perception of the other person’s thoughts and feelings and helps predict how the other person is likely to behave. Music is a powerful elicitor of emotion. Engaging with music requires perception of the emotional and psychological content in music, interpretation of thoughts and feelings, understanding of the complex auditory cues, and experiencing the emotion. Studies have shown that children and adults alike can predict the direction of a melodic phrase or narrative. Empathy is, therefore, strongly connected with perception, interpretation, and our reaction to music. Studies have shown that music enhances prosocial behaviour. Long-term group musical interaction has shown to increase emotional empathy. Several research studies are still being carried out to understand the myriad ways in which music enhances empathy, especially in certain clinical conditions where socio-cognitive deficits play a central role.
Music engages a wide range of neural networks; diverse parts of musical experience are generated by networks formed by several areas of the brain. Music perception involves acoustic analysis, auditory memory, auditory scene analysis, processing of interval relations of musical syntax and semantics, and activation of premotor representations of actions. Music perception alone involves a host of cognitive processes including encoding, storage, and decoding of information and events relating to musical experiences; musical performance extends these processes to reading, motor planning, decision making, and so on. Perceiving the basic acoustic features of music demands awareness of frequency, duration, and loudness. In order to perceive higher-order musical features, an understanding of harmony, intervals, and rhythm is needed. If one focuses and tries to keep track of music in time, both attention and working memory play important roles. Recognizing music and recalling associated memories requires aid from episodic memory. Playing, singing, and moving to the beat of the music involves motor functioning of the brain. Music also influences emotions and the experience of pleasure and reward. Now if we combine the effect of music on various cognitive abilities, it becomes evident that the role of music is crucial in order to understand and modulate cognition in humans.
Music is a combination of multiple processes where producing, listening, and understanding are major areas experts focus upon. Tools such as magnetic resonance imaging15 and brain stimulation techniques are being used to test causal roles of specific targeted brain areas and their inter-dependence. Musical experience, be it producing or listening to it, influences multiple neural networks in the brain which enable specific aspects of music. All brain functions are controlled by networks of brain areas, from primary senses like audition and vision to motor functions, association networks like multisensory integration and spatial navigation, and higher-level cognitive functions like attention, working memory, and learning, all of which are required for proper musical performance. The whole process of understanding and enjoying the music involves not only the auditory cortex and auditory pathways but also the perisylvian network,16 areas of motor network,17 and produces multisensory perception in the brain. This multicentric feeling which makes the brain lit like a bulb on the fMRI shows the complexity of the musical stimulus. The reason behind this multicentric activation is the distributed activation of the grey matter throughout the brain. Beyond the primary auditory cortex, other functional networks such as language and generalized auditory processing, motor pathways, reward pathways, emotions, and visualizations all get activated when the listener experiences the music from its very core. Auditory-motor mapping is an important phenomenon in the understanding of music. The arcuate fasciculus plays a crucial role in mapping sounds to motor motions because it is positioned as a connective conduit between auditory regions in the temporal lobe and motor regions in the frontal lobe.16 Music learning is also one of the complex tasks which involves perceptual, motor, affective, and autobiographical memory integration. It becomes challenging to separately study these behaviours while music is presented as a stimulus. The temporal lobe and superior parietal regions play a crucial role in the interaction of these behaviours and in turn learn the melody, recognizing it, memorising it, and so forth.18 Table 1.1 provides the summary of various brain areas involved in music perception, cognition, and production across studies that have used the functional neuroimaging method. Figure 1.1 provides an overview of different areas of the brain known to be engaged or activated during music-based activities.
Diagrammatic representation of key brain structures relevant to music-related activations.
Neural plasticity is the restructuring or adaptation of the brain caused by the formation of new neural pathways during learning processes. Cognitive neuroscientists working on the concept of music-based therapies, music therapy in collaboration with neurosciences, are particularly interested in a deeper understanding of how music facilitates and enhances neural plasticity. Hebbian learning is the hypothesis that states that synapses that are used repeatedly become stronger over time as a result of repeated exposure to similar sensory experiences.19 In this context, repeated practice and performance of musical activities may provide an appropriate stimulus, altering the shape of brain regions and strengthening their connecting fibres.20 Music therapy for motor rehabilitation is the best illustration of this. Scientists are looking into how music-based therapy might help with speech,21 cognitive,22 and mood problems23 and consciousness disorders.24 In fact, this veritable nature of the human brain is the fundamental principle of music-based interventions.25
To understand the modulations induced by the external stimulus, the first investigations in the field of neuroplastic alterations used animal models. These animal researches revealed some fundamental cortical plasticity rules and demonstrated how cortical neurons use somatosensory modalities (expansion of the receptive field) and spatial tactile discrimination (localization of the receptive field) to make fine-grained temporal judgments. These animal models can be used to investigate the cellular and molecular mechanisms of plasticity in depth. However, the range of stimuli employed, the behavioural manipulation, and the training length, however, limit the investigations. Because cognitive processes involve various molecular and cellular networks, studying them with animal models is difficult due to the large-scale involvement of neural networks. As a result, it became critical to examine human brains in order to resolve these challenges. One of the most challenging endeavours is professional music performance. Music is a multifaceted stimulus with a complex and organised structure. As a result, the richness and complexity of data being analysed by the brain are immense when compared to other external inputs. The integration of sensory and motor information, as well as precise performance monitoring, are required for music composition. The study of musicians may aid in separating the effects of musical training and experience from those of genetic predisposition. Musicians have excellent sensorimotor abilities. Musicians receive continual multisensory feedback as they learn and practise the connection of motor activities with precise sound and musical notation. A musician’s brain could be an appropriate model for investigating neuroplasticity in the auditory and motor domains, as well as the impacts of abnormal plasticity.
Long-term music education has been shown to improve cognitive capacities such as inhibition and planning, according to cognitive neuroscientists. However, ‘far transfer’ does occur in therapy-based treatments, and more research is needed for systematically recording these changes and impact due to the intervention. Musical instrumental training is influenced by several factors, including the learner’s motivation, rhythmic entrainment and social synchrony, musical predispositions, personality, and parental and teacher participation, as well as music-induced rewarding feelings. The practitioner acquires near and far transfer abilities after considering these variables and their effects on cognition. Improved listening abilities, fine motor skills, temporal processing, and attention orienting in time are all examples of near transfer skills. Long-term musical instrumental training, on the other hand, results in improved social skills, increased general IQ, improved executive functioning, improved listening and reading skills, as well as improved verbal memory and vocabulary.26 These modulations or plastic alterations in brain connections are dependent on the practice effect as well as one’s level of expertise.
Music appears to activate pleasure-seeking parts of the brain that are engaged by food, sex, and drugs. Music has four basic structures: iterative, reverting, strophic, and progressive.27 These structures have the capacity to alter the listener’s health and well-being. The activity of several neurotransmitter systems, including dopaminergic, serotonergic, and endorphinic, is influenced by music and its structure. Other chemicals, such as cortisol (the stress hormone) and oxytocin (which promotes social bonding), are also influenced by music and its structure.
The cognitive background of musical appreciation, stress relief, and emotion identification has been largely examined with the heart rate variability (HRV) and hypertension, which seek to explain the cognitive basis of musical appreciation, stress relief, and emotion identification. The signals are carried by messengers in the body that range in size from small to large molecules that are essential for physiological wellness. In other words, music has been demonstrated to have an influence on neurotransmitters and the neuroendocrine system in previous research.28 In comparison to the baseline, music decreases epinephrine (related to fear or anger), norepinephrine (controls heart rate and skeletal muscle contraction), beta-endorphins (blocks pain sensation) and increases opiate receptors (nociception, stress, temperature, respiration, memory, mood, motivation, and so on) and dopamine (enhanced motivation, concentration, and so on). Both stimulating and calming music, on the other hand, have distinct functions to play in determining the levels of these neurotransmitters. Music can alter the immunological response of the body in form of modulating Leukocytes,29 cytokines (Interlukin-6),30 and immunoglobulins (salivary immunoglobulin A-SIgA).31 Music has also been shown to help combat cerebrovascular illness by activating the parasympathetic nervous system and reducing IL-6, tumour necrosis factor (TNF), adrenaline, and noradrenaline concentrations. Before and after gastroscopy, the levels of adrenocorticotropic hormone, cortisol, adrenaline, and noradrenaline were all tested. The generation of biochemical messengers has been demonstrated to be important in giving a soothing effect in older Alzheimer’s patients. Music has been shown to boost immune system activity. Similarly, music influences the amount of hormones in the body of the listener. Hormones such as cortisol (stress hormone, increases glucose in blood stream), growth hormones (maintains body structure, metabolism, etc.), adrenocorticotropic hormone (related to cortisol hormone, and Cushing’s disease), corticotrophin-releasing hormone (hypothalamic hormone), prolactin (milk production, mammary gland development), oxytocin (love hormone, social bonding, attraction etc.), testosterone (growth, reproduction etc.) and others are also modulated by music exposure, resulting in an emotional or physical burst.
The level of brain-derived neurotrophic factor (BDNF) in dorsal hippocampus sub-regions is increased by music exposure, which improves spatial cognition.32 BDNF is a protein that aids in the treatment of depression and improves mood. By assisting in the growth, maturation, and maintenance of neurons, BDNF also aids in the survival of nerve cells. Music can therapeutically alter emotions and autonomic nervous system activity, and it is a potentially low-cost and safe intervention adjuvant. Music stimulates brain areas, causing neurotransmitters to be released. These chemicals rush to our brain, resulting in an emotional response. We react emotionally to what we hear or experience because of these hormones. We may be filled with joy, grief, nostalgia, or enthusiasm. Music helps team members communicate more effectively, reduces anxiety, and increases efficiency. Therefore, surgeons and surgical personnel occasionally listen to music while performing procedures; it reduces the surgical team’s tension as well as the patient’s anxiety prior to surgery.
There is a need to determine the precise activities of cytokines, neurotransmitters, hormones, peptides, and other messengers. While music can reveal such functions by revealing trends in messenger production, it is by no means causative. The potency of another messenger can offset or amplify a trend in the output of one messenger. As a result, comprehending the links between the mind and the body requires an understanding of messenger production pathways. Music may help to balance messenger levels by boosting or reducing steroids in people who have low or excessive hormone levels.
Music instigates human health and well-being while also laying the groundwork for non-pharmaceutical treatments for neurological disorders. Engaging, emotional, physical, personal, social, persuasive, and synchronization are seven aspects of music that aid in the management of neurological disorders, according to the Therapeutic Music Capacities Model (TMCM).32 Therapeutic contexts, active components, brain mechanisms, and effects are all encompassed by music-based therapies. Some of the brain mechanisms behind the benefits acquired by music therapy in neurological disorders include autobiographical memory, language, activation of the mirror neuron system (MNS), auditory motor coupling, stimulation of motivation and reward, and neuroplasticity.
Music, as a structured, complex language of time, provides temporal structures that enhance perception processes, namely in the areas of cognition, language, and motor learning, thanks to its unique capacity to reach affective/motivational systems in the brain. Individual or group music-based therapies can be provided in either passive (listening) or active (e.g., singing, drumming, clapping, dancing) forms, depending on the therapeutic environment. Music-based therapies have been shown to induce brain processes that lead to demonstrable improvements in behavioural, cognitive, motor, and psychosocial domains. Pain, anxiety, agitation, and depression can all be relieved by music. Music can elicit vivid personal memories and associated emotions, reinforcing a sense of identity in people with Alzheimer’s dementia (AD); music-based treatments can improve gait and speech functions in people with Parkinson’s disease (PD); and it can improve attention and understanding of emotions in children and adolescents with autistic spectrum disorder (ASD). Researchers use several music-based strategies to help patients with neurological disorders achieve positive mental transformations, which aids in better medication control.
As we gather experience with how to use music most effectively, its role in fostering positive mental health will continue to rise. Music has the potential to lead society towards a higher level of health – also known as positive health.
• Music promotes brain activity, enhances people’s moods, and encourages social interactions.
• It has the potential to significantly improve brain health and well-being for people of all ages and health levels.
• Music strengthens the cognitive reserve in the brain, promoting resilience. Such abilities can enhance a person’s ability to learn throughout their lives, opening the door to rewarding new experiences.
There is definitely a need to carry out further systematic research on music’s impact on psychological and overall physical health.
More than 100 years ago, German Nobel laureate Robert Koch predicted that ‘a day will come when mankind will have to fight noise as fiercely as human plague or cholera!’. That day is not far away. We live in a world of sound. The sense of hearing is active 24x7 from the fifth month of foetal (intrauterine) life and lasts lifelong. The living zone is ever immersed in both meaningful sounds, such as speech, music, sound alerts (doorbell, traffic alerts, etc.), that are critical to childhood to acquire spoken (verbal) language skills and education, avoid dangers and so forth, and unwanted sounds, often referred to as noise.
In other words, from birth to death, life is bombarded with sounds of various types such as music, speech, laughter, rain, transport, traffic, sports, and so forth. The level of such sounds and noise has been steadily increasing in the past decades owing to mechanization, automation and the more recent, Fourth Industrial Revolution (4IR).
It is said that not only industrial noise but all high-volume sounds such as loud music are harmful to hearing and health. Well-established data is available on all aspects of sound pollution and its harmful effects on human hearing and on other body functions leading to stress, loss of sleep (sleep deprivation), accidents, communication breakdown, blood pressure, cardiovascular disorders, abdominal pain, tinnitus (ringing sound in the ear), giddiness, and so forth.1 Hence, it is time that reasonable action is initiated to reduce the burden on human hearing and health. It is said, ‘you may forgive noise but your body never will’.
In fact, hearing the sounds in our living or working environment and not hearing them for any number of reasons including hard-of-hearing have a significant impact on human sustenance and survival. Therefore, balancing the activities such as hearing the sounds in the living and working environment, be it speech, music, sound alerts, or noise, and not hearing them is critical in the emerging world.
This chapter discusses the evolution of human hearing and its usefulness; how soundscape is a factor influencing exposure to sound (music/noise/sound alerts/speech); the effects of noise/sound on hearing/health and what may happen if we fail to hear them and address ways to contain the problems of sound pollution; a proposed launch of a branch of study – ‘social audiology’ – to address social issues of hearing and not hearing speech, music, sound alerts, or noise and its management.
Learning Objectives
• Evolution of human hearing, its functions and the possible role of artificial intelligence (AI) in shaping the future of evolution of hearing
• Soundscape, sound culture (acoustemology), effect of hearing and not hearing sounds in the immediate environment
• Impact of noise on hearing and safe listening practices
• Impact of hearing loss on a person’s life in creating an inclusive world
• Social audiology and its relevance.
Human Hearing is a mega power acquired over 370 million years of evolution; all began with a fish named Eusthenopteron. A kinked, small bone in the gill opening of a fish called Eusthenopteron developed a larger version of that bone, known as a spiracle. Spiracles, which allowed fish to breathe air while underwater, were believed by scientists to be the missing link between fish gills and land-animal’s ability to hear. Many other evolutionary steps have occurred since, which have developed human’s ability to hear, but it all started with a fish!
In evolution, different species have acquired varying ear, hearing, and sound-processing abilities shaped by need and purpose, including the balance mechanism regulated by the hearing system.
Despite not having an outer ear or middle ear, the early amphibius vertebrates such as salamander and lungfish were able to hear almost 250 to 350 million years ago. In 2015, researchers in Aarhus University2 substantiated that during the transition phase from amphibious vertebrates to terrestrial vertebrates, approximately 100 million years ago, the vertebrates could have been deaf or hard of hearing on land, to an extent of the absence of the outer and middle ear. By design or default, cynodonts (100 to 250 million years ago), mammal-like reptiles, which were nocturnal, escaped extinction from the jaws of dinosaurs, which did not turn nocturnal and evolved a good sense of hearing as it was more useful than a good vision for hunting in the dark.
Anna Ginther says3 that while reptiles like crocodiles and lizards have only one bone in their middle ear, the mammalian middle ear has three bones, namely, malleus, incus and stapes. The three middle ear bones have facilitated hearing high-frequency sounds in mammals though the chimpanzees and humans are in the lower end and dolphins and bats are at the higher end. It is worth recalling that Von Bekesy (1960), Nobel Laureate (1963) in Medicine for his work on hearing, said4 that the ossicular chain acts as a simple lever providing a mechanical advantage that matches the impedance of the air with the impedance of the cochlear fluids. In the context of the auditory system, the single-most-important environmental demand that dictated the evolution of vertebrate hearing is the ability to listen and interpret the soundscape. Those who listened to the sound effectively in inter- and intra-species activities, perhaps, survived longer. For example, according to David Mann of the University of South Florida and his colloborators5, the stranded bottle nosed dolphins and rough-teethed dolphins, among other marines, were found to be having hearing loss. Efforts to include them back in the ocean were not possible as they are found to locate their prey just 2 to 3 yards away as against their hearing peers who could detect preys 100 yards away.
Each species has a hearing that is best suited for its survival in a given environment; not to be labelled as better or worse than the other species. Mammals have a wide range of unique hearing abilities. While humans use sonic range 20–20,000 Hz, the elephants use infrasonic sounds and dogs and bats use ultrasonic sounds to detect and locate. Interestingly, the barn owls with two ears placed at different levels (asymmetrically) on either side of the head have a far superior ability in locating their prey even in darkness than owls with symmetrically placed ears.
The sense of hearing facilitated the ability of a species to locate the source of sound, its distance, and direction in addition to what it could gauge by the senses of sight, smell, taste, and touch. The primary functions are to catch the prey and flee from predators. Modern-day predators are, for example, motor vehicles plying on the urban roads or the verbal intimidation in the living space, to name a few. Human hearing is well adapted to living in a world of airborne sounds despite going through a wide range of civilization shaped by advances in science, technology, and culture.
Hearing, as a function, has come to play a key role in Homo erectus, a social animal. Homo erectus is bestowed with the audio-vestibular system to cope with the needs to survive on land, in water, and in air. The Homo erectus survived through a competitive, threatening evolutionary process with a highly evolved brain to handle complex symbols.
In the civilized world, hearing the sounds is vital to learning verbal language skills for effective communication apart from schooling, employment, interpersonal relationship, recreation, and so forth, all based on the effectiveness of hearing as a sensory system.
Dwelling upon how hearing may evolve to the next level in evolution, less is said about how in the upcoming days/evolutionary process may alter the human ear and hearing, However, the developments in digital technology in conjunction with AI will make the ear as the modern wrist. Digital technology and AI together will not only replace mobile phones but also translate as many as 27 languages, thus making hearing aid as a common man’s wearable. This predicted trend in usage of hearables is a good reason too for the perusal of the ongoing pages.
Also, it is of great interest to note that divers can detect sounds of up to 100 KHz under water as against the upper limit of 20 KHz on land.6 The researcher attributes it to bone conduction clues for the enhanced hearing underwater. Any effort in creating underwater human inhabitants should also take care of the evolution of hearing, soundscape, possible effects of hearing, not hearing, and ways to tackle.
However, as a corollary to the application of AI in hearables, mankind will witness soon a system destined to isolate speech signal among a plethora of other voices and background sounds, no matter what the environment.7
According to International Standards Organization (ISO),8 soundscape is ‘an acoustic environment as perceived or experienced and/or understood by a person or people in context’. The field of soundscape studies and disciplines have evolved differently around the world. It is a perceptual construct of sound scene related to a physical phenomenon (acoustic environment), and, further, the ISO clarifies that the soundscape exists through human perception of the acoustic environment. The sound sources may be sounds generated by nature or human activity and the acoustic environment is the sound received by the receiver from all sources, as modified by the environment. The acoustic environment can be actual or simulated, outdoor or indoor, as experienced or in memory.
It is not out of place to say that the soundscapes are not only unique to a location but also to the person exposed to it. Accordingly, the hazards of harmful noise no longer exist if one does not hear them. In other words, those with difficulty in hearing may find working easier in a noisy soundscape. All those who voice against this on the grounds of non-auditory effects of noise as observed by Kryten9 and Mathias,10 have no evidence to show that non-auditory effects of noise are caused by non-auditory means, leave alone effects of vibration on human hearing and health as documented by the World Health Organization (WHO).11
Interestingly, how mankind had been using sound clues in life and living is scantily documented. In other words, the ‘sound’ culture of mankind is not documented adequately as much as evidence of our ancestors’ lifestyle is being obtained through visual-based observation; for example, the Harappa and Mohenjo-Daro culture is reflected through visual study or inspection of such remains. Realizing the gap in culture studies, a new branch called ‘acoustemology’ is launched to study, understand, and document the sound culture of a society. Steven Feld,12 an American anthropologist coined the term to refer to the ‘sonic way of knowing and being in the world’. The branch of acoustemology can support with the factual role of sound in the daily life of people around the world so that the relevance of hearing and not hearing can be used for realism-based practice.
In addition, many acousticians have studied the acoustic scene analysis and have attempted to classify the environmental sounds. Such studies are conducted for designing of AI-based operations for regulating the functioning of hearing aids, mobile phones, movement of wheelchairs, and so forth.
(i) It is a common sight to see trolley boys in airports gathering and pushing trolleys to their slots. In one such situation, a man wearing two high-end hearing aids walking ahead was hit by the trolley as he failed to hear the sound alerts. Perhaps the hearing aid programming was to capture speech sounds filtering out other sounds in the environment.
(ii) Studies1314 have been done on road traffic accidents among persons with difficulty in hearing with or without hearing loss/hearing aid/cochlear implant or hearables. In a high percentage of road safety incidents involving deaf people, the inability to hear the external audible information was found to be a contributory factor. This is particularly apparent in deaf cyclists, where the evidence indicates an increased risk.15
(iii) Another situation involves the inability to hear the sound of the car engine and to be aware of potential problems through changes in this sound or unexpected noises in the vehicle.
(iv) The use of Active Noise Cancellation (ANC) technology-based ear phones by cyclists or pedestrians and the quietness of hybrid and electric cars claim their toll too.
(v) There is a widely reported case of a lady listening to music at a high volume who failed to hear the sound alerts and was fatally hit by a train at a level crossing.
Prolonged exposure to loud noise as in a generator room or music, say in a club or a one-time exposure to intense sudden bursts as in crackers burst during festivities or bomb blasts, can damage the ear and hearing or cause permanent hearing loss of varying degrees. Noise levels causing damage to hearing and health can be found in places of work, recreational centres such as clubs, stadium, restaurants, marriage halls in India, and in the inclusive classroom or even in the personal audio devices. However, differing susceptibility to the damaging effects of noise has been documented in human populations. Sound is measured in decibels (dB). An ordinary conversation is about 65 dB; an office room is around 50 to 60 dB; hospital wards are less than 50 dB; an autorickshaw is about 80 to 85 dB; music concerts are between 85 and 110 dB; engine testing is 120 dB; a bulldozer or tractor is 110 to 120 dB; crackers are 110 to 125 dB. Sounds at 130 dB induce pain in the ear.
Accordingly, various agencies have recommended cutoff safe hearing levels, that is, permissible dose of sound, be it noise or music or speech.
Human ear’s ability to discriminate pitch and localize sound sources has evolved as secondary derivations as the ear was preadapted to the inevitable presence of noise.16
Toughening of the ear as an example is worth considering here. It has been substantiated with evidences that pre-exposure to continuous low-level noise reduces hearing loss caused by subsequent high-level noise exposure, a phenomenon described as toughening, priming, or conditioning.17 Also, the subclinical exposure to noise may lead to synaptopathy (disorder in the neuronal junction in the transmission of electric nerve impulses), resulting in functional deficits in suprathreshold (above the level of hearing thresholds) levels in primates and non-primates; the toughening effect mitigates both outer hair cell (in the inner ear) damage as well as synaptic loss.
The European Commission18 emphasizes the need to actively manage not only industrial noise but also the sound outside workplaces to enhance citizens’ well-being.
According to WHO, more than one billion people are at risk of hearing damage due to unsafe recreational listening practices. To combat these risks, WHO created the ‘Make Listening Safe’ initiative in 2015.
‘Make Listening Safe’ aims to realize a world where people of all ages can enjoy recreational listening without risk to their hearing.
The approach of this initiative is to change listening practices and behaviours. WHO aims to achieve this through
• raised awareness about the need for and means of safe listening, and
• implementation of evidence-based standards that can facilitate behaviour change in target population groups.
The ‘Make Listening Safe’ mission is developed and carried out in collaboration with all stakeholders in the field.
The WHO creates standards that outline safe listening features for a variety of situations where unsafe practices are common. These include:
• The WHO-ITU Global standard for safe listening devices and systems
• The Global standard for safe listening venues and events.
The above two standards, available freely online, were released on 3rd March 2022 on World Hearing Day celebrated with the theme of ‘To Hear for Life, Listen with Care’. Cafeterias with loud music, for example, are advised to have a silent room for those with hearing fatigue to seclude and give rest to the ear, have an internal noise-level monitor, keep the sound level below 100 dB(A) LAeq, 15min with weekly exposure not exceeding 80 dB(A) for 40 hours.
Noise-induced hearing loss, accounting for 16% of disabling hearing loss in adults ranging from 7 to 21% in various subregions worldwide, denies access to education, employment, health, independent living, justice, recreation, information, and disaster survival. Therefore, as under the provisions of UN Convention on Rights of Persons with Disabilities (UNCRPD, 2006) and Rights of Persons with Disabilities Act 2016 (an Indian Act complying with UNCRPD, 2006), any program dealing with habilitation or rehabilitation of persons with difficulty in hearing needs to resolve issues in realizing their rights.
Hearing loss or not hearing may lead to activity limitation and participation restrictions as outlined in the International Classification of Functioning, Disability and Health of WHO (2001).19 They are Learning and Applying Knowledge (e.g. listening copying, reading), General Tasks and Demands (e.g. preparing, initiating, and arranging the time and space for a simple or complex task; handling responsibilities), Communication (e.g. conversation, communicating using signs), Mobility (e.g. walking, driving, using transportation), Self-care (e.g. toileting, dressing, eating, drinking), Domestic Life (e.g. preparing meals, caring for household objects, assisting others), Interpersonal Interactions and Relationships (e.g. maintaining family relationship, relating with strangers), Major Life Areas (e.g. education, employment, economic life), and Community, Social and Civic Life (e.g. recreation, religious activity, political life).
Needless to say, in order to ensure an inclusive world for persons who do not hear (with or without hearing aid/ear implants), the people in the world of sound need to play a proactive role to ensure equality and equalization of opportunities. Hearing is evaluated in a way as is measured or measurable for clinical purposes; in other words, what is measured is considered as the hearing ability of a person. It is right but not complete. Evolution has supported hearing as a sense for its ability to infer from the sound in its ecosystem to save the species from threats, to get food, and to procreate.
The current-day hearing devices including advanced speech processors do not necessarily take these life-saving social functions of hearing into consideration, thus leaving the users vulnerable to threats of survival and interpersonal relationship crucial for life and living, depending on age. Limited abilities to localize sound sources and other reduced spatial hearing capabilities remain a largely unsolved issue in hearing devices such as hearing aids.20 A study by Dorman et al.21 in 2016 showed that modern cochlear implants do not restore a normal level of sound source localization for listeners fitted with Cochlear Implants with access to sound information from two ears.
The situation is no better among certain categories of deaf people who do not wear hearing devices and thus fail to use clues of sound for life and living. In other words, this is a group of persons devoid of the advantage of hearing sound where hearing is defined ‘as a psychoacoustic experience of sensation and perception of sound that occupies space and time, in the soundscape’. This definition gives scope to incorporate the operational problems of the deaf and need to facilitate getting sound clues either through hearing or through tactile or visual clues (to those who do not use or benefit from hearing aid) in this world of sound. This approach will rectify the impact of not hearing essential sound clues in the living environment, especially of persons wearing hearing aids, cochlear implants, or the deaf persons who do not use amplification devices or those having difficulty in processing auditory signals (Auditory Processing Disorder).
It is not uncommon to read news in media such as, ‘A deaf woman hit by a vehicle in Hollywood’; ‘A deaf man dies struck by a car – 2015’; ‘A hard-of-hearing woman dies in RTA ’; ‘A hard-of-hearing man wearing high-end hearing aids hit by a moving trolley in the airport’ (personal experience of the author); ‘Deaf/hard-of-hearing persons being unaware of bodily sounds such as belching or passing gas’.
(i) Acoustemology needs to be pursued with reference to audiological needs with a focus on studying, accessing, and sharing sonic experience in life and living.
(ii) Technology applications have to be channelized to create an inclusive world to those with difficulty in hearing in a world of sound.
(iii) Definition/scope of audiology has to focus more on the International Classification of Functioning, Disability and Health (ICF)19 framework and assign accountability for such negative conditions arising as a result of hearing or not hearing while wearing an aid, or being a deaf person not using an amplification device.
(iv) Study of soundscape and sonic way of knowing and being in the world have to be emphasized. Soundscape describes the sounds around us in lines with the analogous term landscape to describe the view of all the land around us.
(v) Promoting cues/indicators to provide timely information of crucial changes of the human system and its environment.
Thus, it is hereby recommended to focus on social audiology, operationally defined as, ‘the study of sound scene, making sound clues accessible for activities and participation of persons who have difficulty in hearing, processing auditory information, or deaf (not using amplification devices/dependent on signing) persons, individually and collectively, thus resolving cost-effectively all issues relating to hearing sound with or without amplification devices, in shared family and community living environment’. Social audiology is an open-ended concept which is generative rather than prescriptive and follows realism-based practice (new concept proposed here) where realism is thinking and acting based on facts and what is possible, unlike evidence-based practice, which may sometimes be non-implementable. This branch needs to promote the emergence of a rights-based world as under the United Nations Convention on the Rights of Persons with Disabilities (UNCRPD) (2006) and Rights of Person with Disabilities Act (RPD Act 2016), an Indian Act. The conclusions below reflect the scope of social audiology.
After carefully considering the points raised in this chapter, the following are the conclusions:
(i) Study of sound scene that are part of the lived-in experience of the people (includes heterogenous diverse population) so that technologists and others work out remedial measures. The study may include noise/alerting sound, its audibility, and response of people thus exposed (say in a bus stand), or roadside vendors. The risks of noise for professionals such as a dental doctor, a plastic surgeon or an orthopedic surgeon using noisy drilling machines needs to be studied.
(ii) Preventive and promotive strategies such as (a) public education in universal design, (b) hearing screening activities, (c) public policies, for example, noisy products to be sold along with ear muff and a warning label ‘Noise is injurious to hearing/health’, (d) ensuring accessible and affordable solutions, and (e) standards with essential boundaries than a single boundary need to be prioritized.
(iii) Promotion of environmental facilitators and reduction of the barriers to optimize activities and participation in the ICF framework, for example, (a) changing the attitude, (b) issues in accessing public services, (c) involving in sports and recreation, (d) disaster survival strategies, and so forth.
(iv) Damage control measures to reduce the impact of hearing loss on a person’s life including (a) limitations in the use of hearing technology at bedtime, (b) bullying control, (c) interpersonal issues arising out of not hearing, and so forth.
(v) Guiding and development of appropriate technologies to the heterogenous group of people such as hard-of-hearing/deaf, typical hearing (e.g., public announcements, public convenience, noisy inclusive classroom, communicating in workplace) denied of sound clues, through need and gap analysis. The individual susceptibility for noise-induced hearing loss needs to be studied and understood, so that the cost of universal care and ban on sound pollution may be reviewed.
(vi) Use of standard outcome measures, economic guidelines, and related data management systems need to be augmented.
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