Research Article

Linear and Complex Measures of Heart Rate Variability during Exposure to Traffic Noise in Healthy Women

Figure 2

A MTM power spectrum of a time series of 500 RR intervals in a traffic noise exposure subject. sMTM is the area beneath the spectrum, yet above the baseline created by broadband noise as the signal becomes chaotic. High spectral entropy and high spectral DFA are derived by applying the Shannon entropy and detrended fluctuation analysis (DFA) functions to the MTM power spectrum. Parameters for the MTM power spectra as set at (i) sampling frequency of 1 Hz, (ii) time bandwidth for the DPSS at 3, (iii) FFT length of 256, and (iv) Thomson’s “adaptive” nonlinear combination method to combine individual spectral estimates.