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A Production sample from every 100 units is tested to verify design, materials, and cut-off frequency. The test is conducted in accordance with the Impedance Tube Method- ASTM-C 384-90a. Wedges or sound absorbing elements shall have a low frequency cut-off in Hertz (Hz). Above this frequency, they shall have a coefficient of absorption value of 0.99, or a ratio of reflected sound pressure to incident sound pressure of 10% or less.

After the full installation of the Chamber is complete, a test shall be conducted to guarantee chamber performance. The test is conducted in accordance with ISO 3745: Inverse Square Law, ANSI 12.35 1990 (R1996). Wedges or sound absorbing elements shall have a low frequency cut-off in Hertz (Hz). Above this frequency, they shall have a coefficient of absorption value of 0.99, or a ratio of reflected sound pressure to incident sound pressure of 10% or less.

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