Noise is anything which is unbearable to our ears. Around 170,000 people in Britain suffer deafness, tinnitus (ringing in the ears), or other ear conditions from harmful levels of noise at work. Noise can also be a contributory factor to other health conditions such as psychological problems, trauma, depression, irritation, high blood pressure and even a cardiac arrest.
So, it is important to be able to measure noise levels and there are various ways to do this.
The decibel (abbreviated dB) is a unit used to measure the intensity of a sound. On the decibel scale, silence is 0 dB. A sound 10 times more powerful is 10 dB. A sound 100 times more powerful is 20 dB. A sound 1,000 times more powerful is 30 dB and so on. A scale such as this is known as a logarithmic scale.
Some common sounds and their decibel ratings include:
The human ear distorts its sensitivity to lower and higher frequency sounds. Sound meters try to mimic this process by weighting the readings. This scale is known as the A scale and readings taken using this scale will be denoted as dB(A).
There are three other scales, B,C and D. B is rarely used, C is used for very high levels and D scales is mainly used to measure aircraft engine noise.
This is another noise or sound rating scale. It is not directly proportional to a decibel rating and is mainly used by ventilation fan manufacturers to rate the sound levels of their products.
A sone is a measurement of sound in terms of a comfortable hearing level. The lower the sone value, the more comfortable the listening environment will be. A 4-sone rating is four times as loud as a 1-sone rating (a linear scale not logarithmic like the decibel scale.)
Sones are not decibels or volume, but rather how sound is sensed. Sones are a linear measurement, so doubling the sone value is equivalent to doubling the loudness.
One sone is equivalent to the sound of a quiet refrigerator in a quiet kitchen.
It is important to be able to measure noise levels as being exposed to noise or loud sounds can lead to the condition of noise induced hearing loss. Loud noise and high sound levels are actually covered in health and safety regulations. The Control of Noise at Work Regulations 2005.
So, how to measure noise level with an iphone or android? There is an app for an iphone "Decibel X" it has pre-calibrated measurements and supports dBA, dBC. For android phones "Decibel X" can still be used but there are some other apps worth considering to measure sound levels on a 'droid phone.
So, now we can measure a noise or sound level, let's try and answer some more questions about noise.
A normal conversation is 60 - 70 db. So 68 db is a normal conversation level. A safe or acceptable noise level for constant exposure is 68 db or below.
Hearing damage can occur when exposed to a constant background noise of 80 - 90 db. City traffic is typically 85 db.
Sound levels above 125 db will cause pain in the ear and you must wear hearing protection to prevent hearing loss. A jet engine at 100 feet is 140 db.
Powered tools have different noise ratings, but a safe workplace noise level is always below 68 db.
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