What is sound and what is SNR?

What is sound and what is SNR?

Sound is created when something vibrates and sends waves of energy (vibration) into our ears. The vibrations travel through the air or another medium (solid, liquid or gas) to the ear. The stronger the vibrations, the louder the sound. Sounds are fainter the further you get from the sound source.

 

Sound changes depending on how fast or slow an object vibrates to make sound waves. Pitch is the quality of a sound (high or low) and depends on the speed of the vibrations. Different materials produce different pitches; if an object vibrates quickly we hear a high-pitched sound, and if an object vibrates slowly we hear a low-pitched sound. Sounds are usually a mixture of lots of different kinds of sound waves.

 

What is SNR?

 

SNR is a Single Number Rating system as per the International Organization for Standardization’s ISO 4869 certification. Independent laboratories test earplugs to determine their SNR value. The SNR value can be used to compare the level of noise attenuation offered by different hearing protectors.

 

To determine acoustic pressure on your ears, you subtract the SNR value from the average noise level measured. For example:

 

  • • The music in a discotheque measures an average of 99 dB.
  • • You are wearing the Alpine PartyPlug with an SNR of 19.
  • • Thus, the acoustic pressure on your ears is on average 99 – 19 = 80 dB.

 

The higher the SNR, the higher the level of noise attenuation provided by the earplugs. Bear in mind that the SNR value is a rough average. Earplugs attenuate lower tones differently to higher tones. To understand that, you need to compare earplugs at different frequencies, using H, M and L values.

 

  • • H: High frequencies between 2000 and 8000 Hz
  • • M: Medium frequencies between 1000 and 2000 Hz
  • • L: Low frequencies between 63 and 1000 Hz

 

For PartyPlug earplugs, these values are as follows:

  • • H=19
  • • M=17
  • • L=12

 

If you refer to the table of noise attenuation values for PartyPlug earplugs, it looks as follows. It shows you by exactly how much the earplugs attenuate noise at which frequency.

 

Hz

63

125

250

500

1000

2000

4000

8000

dB

8,8

10,3

13,2

16,6

20,6

25,4

25,2

19,2

 

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