Today, Wednesday March 3rd, is World Hearing Day.
SEPRI Medicina no Trabalho marked the day with awareness campaigns and hearing screenings for its clients where noise in the workplace is a constant.
Workers can be exposed to high levels of noise in workplaces as varied as the construction and textile industries.
But what are the causes of hearing loss?
How can we classify hearing loss from mild to profound?
And which sounds are most damaging to the hearing system?
What is sound, anyway?
Sound is the result of molecules vibrating from one side to the other, creating a sound wave.
These sound waves are picked up and conducted by our hearing system, which transforms them into nerve impulses that are then interpreted by our central nervous system.
Hearing is the first of the five senses to be fully developed at birth.
At around 16 weeks of gestation, the fetus is already able to receive stimuli from the mother’s body and the external environment.
What are the causes of hearing loss?
The causes of hearing loss are not limited to those listed below, but we have highlighted the most common ones:
Age: ageing is the most common and natural cause;
Noise: in prolonged or acute exposure;
Genetic factors: family history can be a direct cause ;
Infections: various viruses and bacteria can damage the hearing system, not only in childhood otitis but also in adulthood;
Ototoxic agents: certain drugs, medicines, alcohol and tobacco can affect the various components of the hearing system.
How is hearing loss classified?
MILD (20 TO 40 dB) – Inability to hear soft everyday sounds.
MODERATE (41 TO 70 dB) – Inability to understand a conversation in a group of people.
SEVERE (71 TO 90 dB) – Inability to hear the sound of instruments, car noise.
PROFOUND (> 91 dB) – Severe dizziness to the point of not hearing the turbine of an airplane.
What are the most damaging sounds for the hearing system?
Decibels is the unit used to measure sound.
To give you an idea, 20 decibels is the threshold of human hearing.
At 85 decibels, we enter the damage threshold and at 135 decibels, we enter the pain threshold.
The sound of a heavy vehicle is around 90 decibels, while a jackhammer registers around 100 decibels.
The sound in a residential area is around 50 decibels. 
