The Research On Effects Of Temporal Envelope Cues In Different Frequency Regions For Mandarin Recognition

Objective: To investigate the relative importance of temporal envelope(TE)cues in different regions for Mandarin sentence recognition in quiet and in noise.Methods: In quiet environment,the MHINT(Mandarin version of Hearing in Noise Test)materials were used as the original materials.The TE information was extracted using Hilbert decomposition from 30 frequency bands which were 1-ERB-wide and then allocated to five frequency regions(Region 1: 80-502 Hz;Region 2: 502-1022 Hz;Region 3: 1022-1913 Hz;Region 4: 1913-3856 Hz;Region 5: 3856-7562 Hz).In noisy environment,the MHINT materials were combined with fluctuating noise(4 Hz)at signal to noise ratio(SNR)of +5 dB.Then the TE information was extracted from the combinations using Hilbert decomposition and then allocated to five frequency regions.Recognition scores were obtained with acoustic TE cues under different conditions.Next,the relative contributions of the TE information from the five frequency regions to sentence perception were computed using a least-squares approach.Results: In quiet environment,the mean weights of Regions 1 was about 0.25,which was the highest of all,while the mean weights of Regions 3 was about 0.22,which was lower than that of Regions 1 but was higher than those of other Regions.In noisy environment,the mean weights of Regions 1 was about 0.46,which was the highest of all,while the mean weights of Regions 2 and Regions 3 were about 0.24 and 0.22,which were lower than that of Regions 1 but were higher than those of Regions 4 and 5.Conclusions: There is a synergistic effect among the TE cues in different frequency regions.The TE cues of Frequency Region 1(80–502 Hz)contributed more to the intelligence of sentence recognition than other regions,especially in quiet environment.