“…Target Generality Knowledge [8], [15], [24], [38], [43], [63], [64], [73], [120], [124] Before Sensor Universal None [7], [31], [36], [45], [49], [61], [87], [88], [93], [103], [110], [140], [141], [145], [147] Between Sensor and ASR Specific Partial [105], [106], [122], [123], [133] Inside ASR Specific Full perturbation cancellation [36], [45], [49], [110], adding distortion [61], [87], [103], signal smoothing [45], audio compression [31], [88], [147]) to destruct the adversarial perturbation (if any) to protect ASR systems. Other works apply an extra detection network [7], [46], [93], [140], [141] or multi-model detection mechanism [145]. However, those defense s...…”