Modern society has created an environment in which the ear is the sensory organ most frequently and easily injured. The ear is not designed to tolerate or exclude many of the sounds and noises generated in today’s industrial society. Loud recurrent noise can seriously injure the ear.
How noise affects us
Humans have five senses: sight, hearing, taste, smell and touch. The sense in first place is sight. It is important for us to be able to perform at school or work.
After vision, hearing is usually considered to be the next most important sense. We use speech and hearing to communicate with each other. Hearing is also our most sensitive and most important warning mechanism. It receives impressions from all directions and is open to impulses both when we are awake and when we are asleep.
Damage to hearing can completely or partially isolate individuals from their surroundings. Such hearing damage can never be repaired. In the past a noisy machine was considered to be a symbol of strength, power and prosperity. People became used to the noise; they accepted it because the noisy machine meant income and sustenance. Becoming deaf or nearly deaf because of noise exposure was considered to be part of the job. Today we do not have to just accept this explanation. We have the ability to reduce or exclude noise, both in the workplace and in everyday life. People just have to be made aware of the dangers and possibilities so that they will want to do something to reduce noise levels. Many experts and researchers consider noise to be one of our greatest environmental problems.
They usually talk about three types of impacts associated with noise:
The psychological impact includes irritation due to continuous or repeated noise. With such disruption the intensity does not have to be high, especially in connection with relaxation and sleep. A dripping faucet or the muffled rumbling of traffic is sufficient. Irritating noise in the workplace reduces work capacity and performance. Generally speaking, irritation rises with sound strength and noise, which contains distinctive, high-pitched tones, is particularly disturbing.
When noise is masking it means that it prevents the ear from perceiving other sounds, such as conversations and warning signals. Masking noise can therefore increase the risk of accidents in the workplace.
Physically, noise primarily affects us by damaging the inner ear, either acutely in response to a very intense noise such as a rifle shot, or gradually through continuous exposure to industrial noise. Other noise impact of a physical nature can include elevated blood pressure, altered respiration and altered gastric acid production. Circulation, sleep and digestion can suffer, leading to headache, nausea, tense muscles, and general mental and physical fatigue, which in turn can impair concentration.
When the ear is stressed with loud noises, the sound-sensitive hair cells in the inner ear can be damaged. The louder the sound, the less time needed for an injury to occur.
When exposed to loud sounds, individuals may experience a feeling of a lid covering the ears, their hearing worsens and they may hear buzzing or ringing in the ears. In most cases, the ear recovers after a while—the damage was only temporary, but still shows that the individual has been exposed to more noise than the ear can tolerate. This clear warning signal should be taken very seriously.
After repeated exposure to loud sounds the ear may eventually no longer be able to recover. The ear has sustained permanent hearing damage that cannot be reversed. There is also a high risk that the buzzing or ringing in the ear will become permanent. Exposure to loud noise primarily affects the ability of the ear to perceive higher frequencies, treble sounds.
Even a relatively moderate hearing loss can cause problems because it often leads to difficulties in understanding conversations, especially in large groups in which several people talk simultaneously, or if background noise is present. In many cases, people do not discover an impending hearing injury until a late stage, because they gradually become used to the worsening situation. To some extent the brain compensates for hearing loss by using other senses, such as by reading lips when others speak. But this response also contributes to delayed detection of hearing impairment.
In most cases, hearing loss is a permanent injury that can only be inadequately compensated by technical means such as a hearing aid.
Tinnitus is defined as perception of sound even when there is no noise in the environment. It can be experienced as buzzing, ringing and monotonous sounds in the head. Tinnitus is often a component of noise damage, but also occurs in connection with hearing loss that has another cause. Tinnitus can also occur even without any measurable hearing loss. When we refer to tinnitus as a problem, we mean permanent tinnitus that bothers the individual. Tinnitus occurs to varying degrees in about 10-15% of the population. Severe tinnitus affects about 3-5%.
The exact cause of tinnitus is unknown. One theory is that the hair cells become so damaged that they send false signals to the brain. The brain perceives these signals as sound. Essentially, the hair cells have been “shocked” by the noise and locked themselves in a position where they transmit signals even when there is no sound in the environment.
In most cases tinnitus is a temporary problem, but for some people it can be permanent, comparable to chronic pain and it is important to seek help. In addition, stress, fatigue and depression can make tinnitus worse. Tinnitus does not respond to treatment with medications or to surgery, but there is treatment that provides relief and support.
Another form of hearing loss that can occur is hypersensitivity to sound, which means that moderately loud sounds are perceived as uncomfortably loud. It often occurs in connection with tinnitus, though not always.
In yet another form of injury, sounds are distorted. Even when sounds are clearly audible, they are perceived with lower quality because of the damage to the ear. Diplacusis, or double hearing, is one form of sound distortion. It can manifest as a pure tone perceived as two tones in combinations that can be very discordant, or the same tone may be perceived as having a different pitch in the left ear than in the right. This condition can be very annoying, such as when listening to music.
One common misconception is that people get used to noise. A positive attitude toward noise will reduce some of the physical reactions, but the adverse effects on the hearing organ are unavoidable, causing fatigue and paralysis of some hair cells. When people become used to noise, it is because they have a hearing loss for the frequencies where the noise is most intense. People who have become accustomed to a certain type of noise may become insensitive to all the frequencies included in just that particular noise.
As mentioned earlier, sound occurs when a sound pressure wave affects the eardrum and the cochlea of the inner ear. The membrane of the cochlea vibrates and affects the sensory hairs, which are bent at the frequency corresponding to the pressure wave. If the hair cells are strongly irritated over time, metabolism is disrupted and the sensory cells become temporarily dysfunctional. The individual becomes hard of hearing. If the cells are allowed to recover in peace and quiet following a stress that is not too strong or prolonged, they can recover and become functional again. If the stress is repeated day after day, the hair cells are unable to normalize between exposures. The blood supply and metabolism of the cell have changed in such a way that it can no longer function.
The worst part about hearing loss is that it is insidious. The high frequencies above the speech range are affected first. The individual no longer hears the birds chirping or crickets singing. In the end, the speech range is also affected.
In the speech range, the consonants disappear first, followed by the vowels. The effect can be surprisingly fast and devastating. Noise damage often results in the generation of nerve impulses, which are perceived as beeping or buzzing, consisting of pure tones or complex tones within a given frequency range; in other words, the individual experiences auditory sensations without any stimulation. This phenomenon can cause extreme mental strain along with the actual hearing damage. It is possible to adapt to noise, but sooner or later a price must be paid for this adjustment.
Hearing damage can never be reversed.