Intelligibilities of Mandarin Chinese sentences with spectral "Holes"

The speech intelligibility of Mandarin Chinese sentences of various spectral regions, regarding band-stop conditions (one or two "holes" in the spectrum), was investigated through subjective listening tests. Results demonstrated significant effects on Mandarin Chinese sentence intelligibilities when a single or a pair of spectral holes was introduced. Meanwhile, it revealed the importance of the first and second formant (F1, F2) frequencies for the comprehension of Mandarin sentences. More importantly, the first formant frequencies played a more primary role rather than those of the second formants. Sentence intelligibilities declined evidently with the lacking of F1 frequencies, but the effect became small when the spectrum holes covered more than 50% of F1 frequencies, and F2 frequencies came into a major play in the intelligibility of Mandarin sentence.