EMD-based EEG signal enhancement for auditory evoked potential recovery under high stimulus-rate paradigm

Averaging of nonlinearly aligned signal cycles for noise suppression

“…For different values of parameters a and b different deformations of the time axis were caused and different final forms of these signals were obtained. To show precisely relation between shape function (34) and the constructed signals, only their parts corresponding to t ∈ (0, 1] are presented, but obviously, according to formula (36), the generated signals extend beyond this time interval.…”

“…. ., N s + 100, (36) where parameter a specifies the number of time samples within the interval (0, 1] and N s > a is the number of samples of the main part of the signal (which undergoes time warping). With the assumed sampling rate of 500 Hz and N s = 400, we obtained signals of 0.8 s length (plus the preceding and succeeding parts of 0.2 s).…”

“…Unfortunately the evoked potentials are mixed with spontaneous EEG signal and can be of low signal-to-noise ratio. Different types of filtering techniques can be applied to raise this ratio [5,1,25,36]; in cases of a very high level of noise, however, they can rarely produce signals of sufficient quality to detect the important deflections and measure their amplitudes and latencies. Thus of high importance are the methods of averaging [6,31] and their modifications [37,20,7].…”

Effects of Speech Phonological Features during Passive Perception on Cortical Auditory Evoked Potential in Sensorineural Hearing Loss

“…This commonly used technique was in line with our present experimental paradigm since we are using 250 ms stimulus duration with long interstimulus intervals (800±200 ms). To resolve the issue of deconvolution (inverse filtering), the standard stimulus which emerged immediately after the deviant stimulus, were excluded from the data analysis (Korczak & Stapells 2010;Wang et al 2013). …”

“…To improve signal denoising process, Wang et al (2013) proposed a method called empirical mode decomposition (EMD). The adaptation of this method was widely used in short inter-stimulus intervals, i.e.…”