Impulsive Sound Detection Directly in Sigma-Delta Domain

Recent implementations of Sigma-Delta (Sigma Delta) converters have achieved low cost, low power consumption, and high integration while maintaining resolution as high as in Nyquist-rate converters. However, its usage implies demodulating the source signal delivered from Sigma Delta modulation to Pulse-Code Modulation (PCM) on a pre-processing stage. This work proposes an algorithm based on Discrete Cosine Transform for impulsive signal detection to be applied directly on a modulated Sigma Delta bitstream, targeting to reduce computational cost in acoustic event detection applications such as gunshot recognition systems. From pre-recorded impulsive sounds in Sigma Delta format, it has been shown that the new method presents a similar error rate in comparison with traditional energy-based approaches in PCM, meanwhile, it reduces significantly the number of operations per unit time.