Healthy Hearing

  • Sound is a pressure wave produced by the vibration of an object.  It is a fluctuation that is transmitted through media (air or solids, liquids) and can be perceived by human or animal auditory organs.

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  • The frequency of the sound is generally expressed in Hertz and is recorded as Hz, which refers to the number of periodic vibrations per second.  Decibels, on the other, are units used to represent sound intensity and are recorded as DB.
  • The higher the pitch, the greater the frequency; the lower the pitch, the less frequency. A sound that can be perceived by the human ear is within the frequency range of 20Hz to 20,000Hz.
  • Noise is an unwelcome sound that can come from many sources - such as human vocal cords, a running engine, a vibrating loudspeaker diaphragm, an operating machines tool, etc.
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  • Noise perception is subjective. Factors such as magnitude, characteristics, duration, and time of occurrence may affect one's subjective impression of the noise.
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Impact of Noise
- It is calculated by the volume and time exposed;
- The greater the volume of noise, the shorter the time of the noise limit;
- Noise causes hair cells of the cochlea to vibrate; hair cells would be destroyed and could not be repaired nor regenerated if volume of noise is great (even if it lasts for only 15 minutes);
- Noise could lead to tinnitus, weak neurological hearing, mental stress and nuisance, as well as interference with daily activities, such as preventing students from doing homework, interrupting us from watching TV and talking on the phone.


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The auditory system is sophisticated in structure and consists of three parts: the outer ear, the middle ear and the inner ear

Acoustic is transmitted to the brain by nerve endings (auditory nerves) to produce hearing while the various parts of the auditory system work together to achieve the function of listening, acoustic and maintaining body balance.

Making Listening Safe

Hearing Music Using Portable Devices

Self Photos / Files - make-hearing-safe1,025 adolescents aged between 12 and 24 was study.  The study found that more than half of those surveyed, 564 (55% per cent), used portable devices to listen to music with a daily average of 60 minutes; 301 (4%) of the respondents listened for 2-3 hours; 89 people (8.7%) listened for 4 hours while the rest had an average of 3-4 hours (44 of respondents, 4.3%). The volume level of the portable device ranged from 1 to 10 (10 is the maximum loudness output). The majority (448 of respondents, 7%) set level at 6-7; 325 respondents (31.7%) maintained level at 5 or lower; 171 (16.7%) set level at 8-9; and 51 respondents (5%) set level at 10.

Self-Hearing Assessment

About 30% of adolescents considered their hearing sensitivity deteriorated; 8% believe their hearing sensitivity became worse while 24.2% considered that their hearing sensitivity was slightly worse than before. 7% of respondents considered their hearing sensitivity was worse than before after turning off their portable device; one fifth of respondents (8%) had tinnitus after turning off their portable device.


Hearing Test
Through pure sound hearing device, pure sound is transmitted to inner ear through ear tube and semicircular canals.  The person receiving the hearing test will be asked to raise hand or press a button every time when sound is heard.

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Level Hearing Loss Communication Problem
Mild 26-40 db Part of the syllable in conversation cannot be heard
Moderate 41-55 db Only 50% of the sound can be heard
Moderate to Servere 56-79 db Only 30-40% of the sound can be heard
Serious 71-90 db Bearly unable to hear and unable to pronounce; vocal sound is low
Very Serious 91 db or above Unable to hear; speech voice is more ambiguous and vocal sound is low

Build a Safe Listening Habit

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  • avoid listening to music in noisy environments as one will unconsciously increase the volume
  • set volume control to low no matter what the rhythm of the music is playing
  • check volume output of portable device and set volume control not more than 60% of the maximum volume.  Do not continue to listen for more than 60 minutes.