A study of hearing acuity and health of the external auditory canal in earphone users

Introduction

The term “noise-induced hearing loss” describes a decline in auditory acuity due to prolonged exposure to noise. The sources of such noise are common and various, recreational and occupational. Many examples can be given, but of particular concern in younger people is the use of personal music devices and regular attendance at clubs and concerts.¹ In light of the coronavirus 2019 (COVID-19) global pandemic, many countries opted for complete lockdowns due to an increasing number of cases.² In order to continue business while complying with the strict lockdown measures, the work-from-home concept has been implemented.^2–4 Furthermore, schooling students also require online learning to ensure learning is not interrupted.^3,4 Additionally, quality headphones are worn while playing video games, which simulate loud, unexpected noises like gunshots, explosions, screaming, and vehicle crashes delivered to the ear in close proximity and are typical causes of early hearing loss. Due to approximately 80% of the population working or studying from home, there is proven evidence of an increase in the use of electronic devices such as earphones for these activities.⁵ Noise-induced hearing loss is a progressive condition that can result in a temporary or permanent notch in the audiogram around 3, 4, or 6 kHz. However, it can also affect higher frequencies.⁶ It is known that the prolonged usage of earphones causes cerumen impaction, which in turn predisposes to otomycosis,^1,4–6 due to the inability of wax extrusion. This study will be primarily concerned with hearing acuity as well as any other complaints related to the use of personal listening devices.

Aim: To study the hearing acuity and health of the external auditory canal (EAC) in earphone users.

Objectives:

Protocol

Discussion

Reduced hearing acuity caused due to excessive noise exposure for a long period of time refers to noise-induced hearing loss.⁹ Exposure to sounds under 80 dB even for long durations is unlikely to cause hearing loss in human ears whereas exposure to sound levels of 130 dB or more even for shorter periods of time can lead to NIHL. The increased prevalence of NIHL in adolescents has been associated with the augmented use of personal music players with loud sound tones and a need for earbuds or headphones.¹⁰ Personal music players or smartphones, which are connected to earphones or headphones, have powerful sound tones, and their maximum volume level can reach 78–136 dB. Noise exposure for a long duration at these levels can lead to noise-induced hearing loss in people using personal listening devices for recreational as well as official purposes. In the post-COVID-19 era, with the new trend of online classes and ‘work from home’, there has been a massive rise in the usage of personal listening devices which has also increased the complaints of hearing loss in adults as well as adolescents. Amongst all impairments, hearing loss is the fourth most common, according to the Global Burden of Disease Study.^11,12 Impaired communication which is a major consequence of hearing loss also has an unfavourable impact on interpersonal relations as well as professional life. Adults with hearing loss that is left untreated not only face physical discomfort but also emotional and financial consequences which lead to social isolation and reduced quality of life.¹¹ According to numerous prior studies, teenagers have symptoms including tinnitus, transient hearing loss, and noise-induced hearing loss because there is insufficient instruction on how to use portable audio devices at acceptable noise levels and for moderate amounts of time to safeguard hearing.^12,13 Along with that, unhealthy practices in using earphones like multiuser sharing or unhygienic use can also lead to conditions like otomycosis and increased wax production. The cochlea is typically the primary locus for pathological signs of noise-induced hearing loss. The increased release of neurotransmitters linked to the cochlea’s transduction function may occur as a result of acoustic overstimulation. Animal studies have provided ample experimental support for the idea that sonic stimulation alters the cochlear blood flow.¹⁴ In particular, there are signs that stimulation with moderately loud sounds increases cochlear blood flow while stimulation with high intensity decreases it (this is a possible mechanism for cochlear dysfunction brought on by noise exposure due to increased metabolic demand).¹⁴ The function of glucocorticoid receptors, oxidative stress, and the fluidity of outer hair cell (OHC) plasma membranes are other metabolic cochlear systems that are the subject of experimental research. Changes to the micromechanical structures within the cochlea have been reported as possible mechanisms of NIHL. It has been suggested that depolymerization of actin filaments in stereocilia may be a substrate of temporary threshold shift.¹⁵ There is evidence that both apoptosis (programmed cell death) and necrosis play a role in NIHL and OHC is particularly vulnerable in such cases.^16,17 It is implied that the progression of OHC death, well after the cessation of noise is due to apoptotic mechanisms. Following an impulse noise exposure, apoptotic changes in chinchilla OHC (specifically nuclear condensation and cell body shrinkage) were detected after 5 minutes, whereas necrotic change (nuclear swelling) appeared after 30 minutes.¹⁷ The adverse effects of excessive noise are not limited to the cochlear hair cells. There is an increasing body of evidence that the synaptic connections between the inner hair cells (IHCs) and spiral ganglion cells may be especially susceptible to noise insults (and indeed to aging), and that this may occur even when the hair cells themselves remain intact.¹³ According to several surveys, at least 90% of teenagers use personal music players and headphones from the manufacturer.¹⁸ In environments with ambient noise, such as crowded streets and public places, they also exhibited a tendency to listen at greater volumes.¹⁸ For instance, the results of a Delphi survey revealed that most teenagers intended to turn up the music volume when there was background noise in order to hear the music better.¹⁹ These unwanted ambient noises can be minimized by a new noise-cancelling feature in earphones and headphones.¹⁹ The basic mechanism involves the production of an anti-noise signal, i.e. a sound wave with a phase exactly opposite to that of the background noise by the noise cancelling circuit which prevents the environmental noise from reaching the tympanic membrane. Low-frequency noise (less than 1 kHz) is effectively reduced by this active circuit, however, the attenuation of higher frequencies is comparatively less effective. Passive noise reduction can be done for higher frequencies by simply wearing a headphone. Theoretically by combining these two mechanisms i.e. active and passive, the NCH (noise cancelling headphones) are considered a good choice for the diminution of ambient noises thus allowing the users to enjoy music in noisy environments without risking hearing loss.²⁰