10. The computer-readable hardware medium of claim 9 , wherein γ qjk den (t) is adjusted according to soft confidence training, wherein: 
 γ qjk den ( t )= q ( t )γ qjk den ( t ).
9. The computer-readable hardware medium of claim 8 , wherein the instructions to estimate model parameters include instructions that when executed cause the computing system to: calculate the update formulas for mean (μ jk ) and variance (σ jk 2 ) for a jth state and a kth mixture model as: μ jk = θ jk num ⁡ ( O ) - θ jk den ⁡ ( O ) + D jk ⁢ μ jk ′ γ jk num - γ jk den + D jk σ jk 2 = θ jk num ⁡ ( O 2 ) - θ jk den ⁡ ( O 2 ) + D jk ⁡ ( σ jk ′2 + μ jk ′2 ) γ jk num - γ jk den + D jk - μ jk 2 where γ jk den = ∑ q = 1 Q ⁢ ∑ t = e q e q ⁢ γ qjk den ⁡ ( t ) ⁢ γ q den θ jk den ⁡ ( O ) = ∑ q = 1 Q ⁢ ∑ t = e q e q ⁢ γ qjk deb ⁡ ( t ) ⁢ γ q den ⁢ O ⁡ ( t ) θ jk den ⁡ ( O 2 ) = ∑ q = 1 Q ⁢ ∑ t = e q e q ⁢ γ qjk den ⁡ ( t ) ⁢ γ q den ⁢ O ⁡ ( t ) 2 where γ q den is the qth word/phone arc posterior in the decoding lattice, and γ qjk den (t) is the posterior on the qth word/phone arc.