Differences in the spatial integration of discrete/continuous spectral signals

We explore the auditory perceptual property of virtual source width (VSW) expansion of synthetic vowels /a/, /i/ and /u/ and compare it with that of natural vowels. We also modify the synthetic vowels by adding white noise at the excitation or at the output. We observe that continuous vowel spectra creates a more stable VSW perception than discrete spectra. We also observe that the listeners perceive predominantly one source in case of shaped noise vowel and two sources in the case of additive white noise vowel. This observation shows that the shape of additive noise spectra plays a significant role in perception. This is quantified through the perceptual degree of VSWe. Additionally, we see a consistent increase in the perceived source width when the degree of non-stationarity is increased.