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There will be a different
frequency sound absorption coefficient. People use the sound
absorption coefficient frequency characteristic curve describing
the sound absorption performance at different frequencies of
sound insulation materials. In accordance with the ISO standard
and the national standard, the frequency range of sound
absorption coefficient in the test report is 100-5KHz.
The numerical absorption coefficient 100-5KHz are averaged to
get the average sound absorption coefficient, the average
absorption coefficient reflects the overall performance of
sound-absorbing sound-absorbing material. Acoustic performance
in engineering commonly used noise coefficient NRC rough
evaluation in language frequency range, which is a numerical
arithmetic insulation materials in the absorption coefficient
250, 500, 1K, four 2K frequency on average, four to five homes
in rounding to 0.05. Is generally believed that the
sound-absorbing material NRC is less than 0.2 is reflecting
material, NRC is greater than 0.2 of the sound-absorbing
material is considered sound-absorbing material.
When the need to absorb a large amount of energy to reduce
indoor noise and reverberation, often need to use the high sound
absorption coefficient of the absorbing material. Such as
polyester fiber sound-absorbing cotton (cotton insulation,
sound-absorbing sponge) Pyramid, wave absorbing sponge,
centrifugal glass wool, rock wool etc. belong to the high NRC
absorption material, polyester fiber sound-absorbing cotton 5cm
thick 35kg/m3 (insulation cotton) NRC can reach 0.95.
.