HOW HEARING WORKS
How your ear works - Inside the Human Body: Building Your Brain - BBC One
Other things you might like to know
The human hearing range is described by pitch measured in Herz (Hz) and loudness measured in Decibels (dB). We hear many different types of sounds from the gentle falling of leaves to the roar of jet engines. In our industry we all this the audible range.
A person with a normal hearing range can hear between 20 (Hz) to the highest possible without pain 20,000 Hz. Our most sensitive range is between 2000 - 5000 Hz.
At Smiths Hearing Care we measure the pitch your hearing at 125 Hz up to 6000 Hz. This is the range that effects how you hear speech.
Humans can hear from 0 dB but sounds louder than 85 dB can be dangerous after prolonged exposure. Normal speech is in the range of 20 to 60 dB. According to the World Health Organisation a hearing loss is graded as follows:
0 - 25 dB Normal hearing
26-40 dB. Mild Loss
41 - 60 dB. Moderate Loss
61 - 80 dB Severe. Loss
Over 81 dB Profound Loss
At Smiths Hearing Care we test your hearing to measure the quietest sounds you can hear.
How Hearing Damage Happens
Deep inside the ear lays the cochlea and within the cochlea there are small nerve cells with thousands of tiny little hairs known as cilia. As we get older these tiny hairs get worn out. A bit like a doormat that is constantly being walked over, the hairs get flattened and the older we get he more worn out they can get. That is why many elderly people don't hear so well. In our industry we call this an age-related hearing loss or presbycusis. Loud noises can also damage the cilia this can happen instantly after hearing an extremely loud noise. The damage can also get caused by overburdening your ears if you are exposed to noises over 80 decibels for too long or too often. The cilia unfortunately do not recover from this damage by themselves; and to this day there have been no medical ways discovered that can repair the damaged cilia.
See the examples below of some of the everyday things we are exposed to.
Everyday sound levels measured in decibels
10 Decibels: are almost inaudible - a leaf falling
20 Decibels: Rustle of leaves
30 Decibels: Very quiet - whispering
40 Decibels: Living room, quiet classroom
50 Decibels: Limited Sound Refrigerator working, car passing
55 Decibels: electric toothbrush
60 Decibels: Sound of human voices normal conversation, sewing machine, television
We talk at a levels of between 20 to 60 decibels
65 Decibels: Electric Shaver
70 Decibels: Irritating - Television set on too loud, vacuum cleaner, several people on the telephone.
75 Decibels: Constant sound - busy restaurant or bar
Long term exposure to sounds below 80 decibels should not effect your hearing.
Repeated, long-term exposure to sounds above 80 decibels can lead to permanent damage.
80 Decibels: Unpleasant - Around 5 hours and 30 minutes a day at this level can cause temporary hearing loss. The weekly limit at this level is 40 hours. Alarm Clock, door bell freight lorries, motor cycles.
85 Decibels: Loud - Heavy traffic, Food processor
90 Decibels: Extremely unpleasant - Screaming, yelling, shouting, lawn mower. Around 30 minutes a day at this level can cause temporary hearing loss. The weekly limit at this level is 4 hours
95 Decibels: Noisy - Drill, violin. Just 10 minutes a day at this level can cause temporary hearing loss. The weekly limit is around 1 hour and 15 minutes.
100+ Decibels: No more than 1 minutes of unprotected exposure can risk permanent hearing loss.
100 Decibels: Extremely unpleasant - Machine in a factory, compressor, fighter jet at 300 m. Even a few minutes a day can cause temporary hearing loss. The weekly limit at this level is around 15 minutes.
105 Decibels: Even Louder - Helicopter close by, large drum
110 Decibels: Extremely Loud - Rock concert
120 Decibels: Human voice at its loudest, police siren
130 Decibels: Thunder Clap
140 Decibels: Pain Threshold
150 Decibels: Permanent damage to hearing - Fireworks
160 Decibels: Shooting with pistol or riffle
170 Decibels: Shot gun
180 Decibels: Rocket Launch platform
191 Decibels: Sound waves become shock waves