{'fraction_non_alphanumeric': 0.013953488372093023, 'fraction_numerical': 0.00813953488372093, 'mean_word_length': 4.937931034482759, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Reduction of noise transmission through an aperture using active feedforward noise control.

A local active noise control technique has been applied to reduce noise emission through an aperture in the wall of the enclosure. Pressure cancellation was effected at the center of an aperture of 0.3×0.3 m2 for an enclosure of 2 m3 volume, and the reduction in sound was measured at various locations at the aperture and at some distance from the enclosure. The results showed that sound pressure cancellation at the window implies emission attenuation through itself, and a relationship between attenuation at the window and outside the enclosure is confirmed. The behavior of attenuation results at the window is related to frequency, to the modal density of the sound field in the enclosure, and to the distance between the error microphone and secondary source.