Robust formant features for speaker verification in the lombard effect

This paper presents a voice controlled speaker verification system for hand-held devices in noisy environments. In noisy environments, users unintentionally increase their voice intensity because of the ear-mouth feedback mechanism i.e., the Lombard effect; thus, the characteristic of the input signal is much different from that in a quiet environment. To enhance the accuracy of a speaker verification system, this paper proposes a robust formant feature that represents the physical nature of the voice production system of the speaker. It utilizes the analysis results that the impact of Lombard varies depending on the types and levels of the background noise, but the third and fourth formant frequencies are insensitive even in the Lombard condition. Experimental results show that optimal performance can be achieved when the above formant frequencies and corresponding bandwidths are combined.