Universal Testing & Research Center (Division of Sustainable Stewardship Private Limited), an ISO 17025:2017 certified Laboratory approved by BIS, NABL and QAI.Noise Reduction Coefficient (NRC) testing is a standardized method used to measure the sound absorption properties of materials, including acoustical panels, ceiling tiles, and wall coverings. The NRC rating quantifies how effectively a material absorbs sound across a range of frequencies. It is expressed as a decimal between 0 and 1, where a higher NRC indicates better sound absorption.

• Test Setup:
  NRC testing is typically conducted in a specialized acoustic testing laboratory or facility. The test setup involves mounting the material being tested on a wall or in a test chamber.
• Sound Source:
  A calibrated sound source produces sound waves that impinge on the material's surface. The sound source emits pink noise, which contains equal energy per octave and simulates a broad range of frequencies.
• Microphones:
  Microphones are strategically placed in the room or test chamber to measure the sound levels. These microphones record the sound pressure levels before and after the sound waves interact with the material.
• Reverberation Time Measurement:
  The test includes measuring the reverberation time in the room both with and without the material. Reverberation time is the time it takes for sound to decay by 60 dB after the sound source is turned off.
• Calculation of NRC:
  The NRC is calculated based on the measured absorption coefficients at different frequencies. The absorption coefficient represents the fraction of sound energy absorbed by the material at each frequency.
• Frequency Range:
  NRC testing covers a frequency range from 125 Hz to 4000 Hz, divided into narrow one-third octave bands. This range allows for a comprehensive evaluation of the material's performance across different frequencies.
• Standardized Reference:
  NRC testing is conducted following the procedures outlined in ASTM C423 for laboratory measurements or ISO 354 for field measurements. These standards provide detailed guidelines for test conditions, instrumentation, and calculations.
• NRC Rating:
  The NRC rating is a single-number metric representing the average absorption performance of the material across the tested frequency range. A higher NRC indicates better sound absorption.

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