Synthetic signals with multiple nonstationary oscillatory components. Each column corresponds to an independent realization with the same background but different oscillation periods. Rows from top to bottom: (1) background components (red + white noise with a flare profile); (2) injected oscillations with time-varying amplitudes and periods; (3) composite signals; (4) global Fourier power spectra (FFT+MCMC); (5) detrended wavelet spectra (CWT+AR(1), detrending scale 290 s); (6) wavelet spectra from the CWT+MCMC method. One component has a characteristic period of ∼16 s, while the second varies across columns (32 s, 50 s, 85 s, and 160 s). Black contours mark the 95% confidence level.