Jacob Zurasky ECE5525 Fall 2010
Goals ◦ Determine if the principles of speech processing relate to snoring sounds. ◦ Use homomorphic filtering techniques to analyze snoring for pitch and also vocal tract response. ◦ Develop a method to distinguish a simple snore from a sleep apnea event.
Store amplitude and frequency spectrum data to SD card Interface to Sleep Lab polysomnogram equipment
Top Figure is the frequency spectrum (0-2kHz) Bottom figure is the snore amplitude
Assume: s[n] = h[n] * p[n] FFT -> log( ) -> IFFT, yields the cepstrum Separate by low quefrency liftering FFT -> exp( ) -> IFFT, vocal tract response
Assume: s[n] = h[n] * p[n] (palatal flow) Use sliding hamming window, 50% overlap Analyze different sounds clips for differences in h[n] and p[n] between normal snoring and an apnea event.
p[n], ‘Voicing’, of the sleep apnea files has a much larger magnitude in the cepstral domain. Vocal tract response during a simple snore is more stable than during an apnea. Vocal tract response is slower changing during a simple snore.
Redesign the SRD to incorporate the functions of the MATLAB code. Faster processor, floating point architecture Continue research to develop a method for in home screening of sleep apnea.