{'fraction_non_alphanumeric': 0.023107569721115537, 'fraction_numerical': 0.0, 'mean_word_length': 5.507772020725389, '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}}
A Novel Fourth-order Adaptive Differential Microphone Array Beamformer for Speech Enhancement

Differential microphone array (DMA) has attracted wide attentions due to its high directivity and small size, however, its poor robustness seriously hampers its applications. In this paper, we develop a novel fourth-order adaptive differential beamformer using a small microphone array for speech enhancement. First, by a use of the two existing differential beamforming algorithms, a new beamformer that improves its robustness while ensuring its high directivity is developed. Second, an improved adaptive noise canceller (ANC) is used to further improve the spatial directivity. The improved ANC consists of two novel blocking matrixes (BMs) and a frequency NLMS adaptive filter with a weight coefficient update control mechanism. One of the novel BM is designed to cancel residual interference by compensating interference loss at low frequency part, while, another is exploited to calculate the control mechanism using fourth-order DMA method. The control mechanism is realized by a signal-to-interference (SIR) ratio. The simulation results show that the proposed method effectively suppresses the noise while ensuring the integrity of the target signal.