What was the attenuation achieved by Willard Meeker's AFRL model integrating ANC with earmuffs?
Answer
Roughly 20 dB in the 50–500 Hz bandwidth.
The project led by Willard Meeker at the Air Force Research Laboratory (AFRL) between 1956 and 1957 represented a crucial engineering step forward by creating tangible hardware. This model successfully integrated active noise control technology directly with existing passive sound protection, specifically earmuffs. The resultant hardware achieved a measurable and substantial performance gain for hearing protection in loud cockpit environments, demonstrating an attenuation of approximately 20 dB. This attenuation was specifically targeted and effective within the lower frequency range of 50 to 500 Hz, showcasing the capability of early applied ANC systems.
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