How to Measure Sound Level
The ability to measure sound level is essential to help determine the fine line between the sound that can be accommodated by human ears and that which would most likely cause damage of some kind.
The energy in a sound wave is measured in units called decibels. Amplitude refers to the force of a sound wave, and it is usually measured in dBA which implies decibels of sound pressure.
Research has shown that the softest sound level that can be heard by humans is 0 dBA and a normal speaking voice is around 65 dBA. Some musical concerts such as a rock concert can make sounds as loud as 120 dBA.
Loud sounds as high as 85 dBA could lead to permanent ear damage. Also, the intensity of pressure accompanying a sound determines the duration it would take to cause damage. Typically, the higher the pressure a sound has, the less the time duration that would be required for damage to occur.
A sound at 120 dBA can begin to damage your hearing after only about 20 minutes while a sound at 85 dBA could take as long as 8 hours to eventually result in permanent damage.
Decibels are a base 10 logarithmic unit which implies that sound intensity would double if it is increased by 10 decibels. To measure the sound level, there are three main methods:
- Decibel Noise Comparison Chart
- Aid of instruments
- Mathematical method
1. Decibel Noise Comparison Chart
|Decibels||Example Sources||Health Effects|
|30||Quiet rural background noise||None|
|40||Library noises, quiet urban background noise||None|
|50||Relaxed conversation, ordinary suburban activity||None|
|60||A busy office or restaurant noise, loud conversation||None|
|70||TV volume, Freeway traffic at 50 feet (15.2 meters)||None; unpleasant for some|
|80||Factory noise, food processor, car wash at 20 feet (6.1 meters)||Possible hearing damage after lengthy exposure|
|90||A lawnmower, motorcycle at 25 feet (7.62 meters)||Likely hearing damage after lengthy exposure|
|100||Outboard motor, jackhammer||Serious damage likely after lengthy exposure|
|110||Loud rock concert, steel mill||May be immediately painful; damage after lengthy exposure very likely|
|120||Chainsaw, thunderclap||Usually immediately painful|
|130-150||Jet takeoffs on an aircraft carrier deck||Immediate hearing loss or eardrum rupture possible|
2. The aid of Instruments to Measure Sound Level
Under this method, there are three different ways of measuring the sound level.
- Mobile Apps for Sound level measurement
- Using Digital Decibel Meter
- Computer (Math) Method
Using a Computer
Given the correct computer programs and relaxation equipment, measuring the sound level using your computer is very possible. In order to do this, you would need to activate the internal microphone that accompanied your computer.
This could give you your desired results, however, it is advisable to get better recording equipment in order to get better results. An external microphone of very high quality would guarantee that you get the sound more accurately.
While making use of your computer, here are a number of ways to take the decibel measurement.
- Provided you have a minimum of Windows 8, you can go the Microsoft App store and download the Decibel Reader application available there free of charge. This app makes use of the computer’s internal microphone to detect sounds up to as high as 96 decibels.
For people making use of Apple products, there are similar applications available in the iTunes app store.
- A third-party program can also be used to measure sound levels. Audacity is one of the many free sound recording programs available which also incorporates a built-in decibel meter.
Using a Mobile App
Mobile apps are especially great to measure sound level while on the move. Mobility certainly doesn’t allow for setting up your computer mad related equipment which makes using mobile apps very convenient.
Although your mobile device may not have a microphone of as high a quality as your computer or the external microphones you connect to your computer, they can be pretty accurate as well. It has been noted in most cases that the readings obtained from mobile apps are usually within 5 decibels of the readings gotten using professional, Hi-Tech equipment.
Here are a number of mobile apps that you can make use of depending on the type of mobile device that you are making use of. These decibel-reading applications can be found on nearly every mobile platform, so it’s the easiest way to measure sound level:
- iOS: Decibel 10th, Decibel Meter Pro, dB Meter, Sound Level Meter.
- Android: Sound Meter, Decibel Meter, Noise Meter, decibel.
- Windows Mobile: Decibel Meter Free, Cyberx Decibel Meter, Decibel Meter Pro.
Using Digital Decibel Meter
Decibel meters remain the same most accurate and authentic way of getting decibel levels of different sounds. Although the device is relatively expensive, it saves a lot of stress and gets rid of a lot of uncertainties associated with using other methods of determining decibel levels.
You can buy a good sound level meter from stores as well as online retailers like Amazon. It typically functions by measuring the amount of noise present in the environment and giving a very accurate decibel value.
Most decibel meters are digital, therefore, the decibel level is displayed on the screen.
To purchase the best decibel meter, you might be spending upwards of $200 and this is typically for the low-cost models. Decibel meters also have a number of other names they are known by.
A noise dosimeter basically performs the same function as a decibel meter or sound level meter.
3. Mathematical Method of Noise Level Measurement
Under the mathematical method, there are four main steps to determining the sound level.
Determine the Sound’s Intensity in Watts/ Square Meter
Although decibels are easily measured for everyday practical purposes, the unit is not as easy and straightforward as it seems or sounds. Decibels are a very convenient way of conveying the intensity of a sound wave across in physics.
Basically, the higher the amplitude of a particular sound wave, the more the amount of energy that it would subsequently transmit. Also, it would move a larger amount of air particles present in its part, therefore, increasing the intensity of the sound produced.
Since there is clearly a direct relationship between volume and sound wave intensity, this provides a way of determining a decibel value from just the intensity level.
The intensity level is usually measured in watts/square meter and the value is usually very low for ordinary sounds. A sound with an intensity of about 5 ×10-5 (or 0.00005) watts/square meter translates to only about 80 decibels which os the volume of a food processor or blender.
To get a better understanding of the relationship between decibels and intensity measurement, here is an example. If a background noise of 1 × 10-11 (0.00000000001) watts/square meter is detected in a music video, the following steps would help you learn how to determine the decibel level of this background studio noise.
Divide by 10-12
Upon determining your sound intensity, all you have got to next is insert the value into the mathematical formula 10Log10(I/10-12)( where “I” is the value of your intensity in watts/meter) and use it to determine your decibel value.
To begin the operation, divide it by 10-12 (0.000000000001). 10-12 is merely a representation of the 0 decibel sound intensity, therefore by comparing the intensity of your sound to this value which serves as a base value, you can easily get the relationship. In this example, we’d divide our intensity value, 10-11, by 10-12 to get 10-11/10-12 = 10.
Take the Log10 of Your Answer and Multiply By 10
To complete solving your calculation, you need to take the base 10 logarithm of your answer, then, multiply it by 10. This is due to the fact that decibels come as logarithmic units with a base of 10 which simply implies that the only time the loudness of a particular sound would double is when it experiences an increase of 10 decibels.
From the example, Log10(10) = 1, 1 × 10 = 10. Therefore, the studio back noise had a loudness 10 decibels. While this is relatively quiet seeing that it is in the range of breathing sounds, it can still be detected by high-quality sound recording equipment. Given a situation like this, it would be essential to get rid of these extra noises in order to get clear recordings.
Understand the Logarithmic Nature of Decibel Values
Since it has been established that decibels are logarithmic values with a base of 10. Therefore, considering a particular decibel value, a noise 10 decibels greater would be twice as loud. Similarly, a noise that is 20 decibels greater would be four times as loud.
The ease of sound identification by the human ear is enhanced making it easy to identify a very wide range of noises. The loudest sound that ear can hear without experiencing any form of pain more than a billion times more intense than the quietest sound it can detect.
Basically, the use of decibels helps to eliminate having to use very large values, making it easier to refer to sound values.
Determination of sound levels is very essential especially in places where ear-damaging sounds are likely to make such as construction sites and music studios. Remember to pin down the sound at a level where it is safe to be heard by everyone.
With given three different ways to measure sound level, you can easily make use of either to determine the sound level of your environment and stay within safe limits.