Hearing Protector Performance and Standard Deviation

Modern designs of affordable hearing protectors are used in noisy situations for the purpose of reducing an exposure to the excessive noise. There are three broad methodologies for categorizing the selection method and the specifications of the attenuation performance of hearing protectors. These methodologies are the octave band, single number, and multiple numbers.

The single number system

The single number systems supply a single number which is a representative indication of the sound immersion’s attenuation for the individual using any hearing protector. The user-friendly nature of this system gives different benefits for every user. However, the main problem with this system is to encapsulate different information in a single figure.

A multiple number system

A multiple number system tries to overcome the difficulties of different attenuations over the several octave ands. This is because specifying expected attenuations for the low, medium and high frequency ranges. This system is implemented by the graphical or numerical method and better than the single number system as it includes multiple frequencies. The important drawback of this system is the increased complexity of application.  

The octave band method

The octave band method maximizes the complexity of specifying specific hearing protectors.  However, the main benefit of this system is directly addressing the necessary attenuations at every octave band. This precise specification of attenuation characteristic required by the hearing protector gives major benefit for users of this system.   

The attenuation performance

As a beginner to the hearing protector, you may require understanding the role of the attenuation performance of the hearing protection. The hearing protector’s attenuation performance is used for estimating the user’s exposure level. The main purpose of this estimation is to reduce the exposed level to an acceptable value. 

Every user must expect this value to fall within a reasonable range around a norm. There is a negative association between the standard deviation and attenuation performance. This result is usually deducted by using a variation in method of appraising the single number rating of attenuation which is more amenable for drawing statistical inferences. 

The overall performance is specified as the function of the mean attenuation minus 1 or 2 standard deviations from the mean. This is because to make certain more than 50% of the wearer population are successfully protected. Many numbers of users of the hearing protectors in our time are experiencing over protection as the increased standard deviation with the decreased attenuation.   

Volunteer human test subjects with good hearing ability are used to assess the hearing protector attenuation performance in the laboratory. These test subjects are usually exposed to low levels of noise while wearing and not wearing the hearing protector. Different frequency ranges of noise are used to find out the mean attenuation at the different octave bands. This process is also used to find the standard deviation of the mean attenuation at all octave bands individually.  All users of the first-class hearing protection devices these days prevent themselves from the noise-induce hearing loss. They reduce the amount of the noise reaching their ears. 

Useful Links: 

Hearing Protector Performance: How They Work - 3M

Noise Reduction Rating (NRR) Explained - AudioReputation

Checking Hearing Protector Performance with the NRR Method - NoiseMeters

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