EURASIP Journal on Audio, Speech, and Music Processing

Table 2 The effect of modifying the normalized reference frequency, λ₀, on the recognition performance of the proposed GMM-HMM EASR system (in terms of WER (%)) for Persian ESD. The values of WER are obtained by applying different warping methods to various acoustic features extracted from different emotional utterances

From: Feature compensation based on the normalization of vocal tract length for the improvement of emotion-affected speech recognition

Feature type	Warping type		Emotional states
Feature type	Warping type		Anger	Disgust	Fear	Happy	Sad	Average WER
MFCC	DCT Warping	λ₀ = 0	42.30	24.54	36.08	29.70	26.43	31.81
		λ₀ = 0.4	28.20	22.34	31.32	18.78	18.25	23.78
		λ₀ = 0.7	38.36	21.79	31.87	19.14	21.48	26.53
	Filterbank & DCT Warping	λ₀ = 0	42.13	23.81	34.25	30.05	21.48	30.34
		λ₀ = 0.4	27.05	21.61	32.42	20.21	15.97	23.45
		λ₀ = 0.7	40.82	22.71	33.52	22.72	21.29	28.21
M-MFCC	DCT Warping	λ₀ = 0	36.07	19.41	27.11	24.15	20.15	25.38
		λ₀ = 0.4	17.21	16.30	21.61	16.10	19.01	18.05
		λ₀ = 0.7	29.67	15.93	21.98	17.35	17.49	20.48
	Filterbank & DCT Warping	λ₀ = 0	34.26	17.95	25.82	23.79	20.72	24.51
		λ₀ = 0.4	22.79	15.93	24.73	17.35	20.53	20.27
		λ₀ = 0.7	31.48	15.38	27.84	18.96	18.25	22.38
ExpoLog	DCT Warping	λ₀ = 0	37.87	16.12	26.01	26.83	20.34	25.43
		λ₀ = 0.4	37.54	14.65	25.64	27.55	20.34	25.13
		λ₀ = 0.7	30.00	13.00	23.26	20.04	16.54	20.57
	Filterbank & DCT Warping	λ₀ = 0	30.49	13.55	15.02	22.72	15.78	19.51
		λ₀ = 0.4	32.46	13.92	16.12	28.98	19.01	22.10
		λ₀ = 0.7	26.89	12.82	17.22	22.18	20.53	19.92
GFCC	DCT Warping	λ₀ = 0	40.66	44.51	48.72	44.90	27.38	41.23
		λ₀ = 0.4	26.89	39.74	43.77	39.53	26.81	35.35
		λ₀ = 0.7	28.52	40.66	43.96	42.58	31.94	37.53
	Filterbank & DCT Warping	λ₀ = 0	39.67	43.77	47.44	44.01	27.19	40.42
		λ₀ = 0.4	28.36	40.84	45.60	40.79	29.09	36.94
		λ₀ = 0.7	30.82	40.84	44.51	43.83	34.79	30.96
PNCC	DCT Warping	λ₀ = 0	3.93	5.13	5.31	6.80	5.70	5.37
		λ₀ = 0.4	4.10	5.13	4.40	6.26	4.56	4.89
		λ₀ = 0.7	4.10	5.13	4.40	6.26	4.56	4.89
	Filterbank & DCT Warping	λ₀ = 0	3.93	5.13	4.58	6.62	5.70	5.19
		λ₀ = 0.4	3.93	5.31	4.95	6.44	5.32	5.19
		λ₀ = 0.7	3.93	5.31	4.95	6.44	5.32	5.19

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