LINEAR PREDICTION SPECTRAL APPROXIMATION
Clean Speech (25.3 dB SNR)
Noisy Speech (2.1 dB SNR)
Linear Prediction (LP) is an efficient spectral estimation technique which gives us an all-pole model of the spectrum.
LP breaks down in noisy conditions; it uses up its limited poles to model noise.
Notice the loss of the second peak, there goes the SECOND FORMANT!