Table 2.

List of the first 30 selected features for the comparison between C and PWS during the sustained emission of a vowel.

No	Group	Family	Low level descriptor	Functional
1	Cepstral	Spectral LLD	MFCC 1–14	Standard deviation
2	Prosodic	Energy related LLD	Zero crossing rate	Relative peak range
3	Prosodic	Energy related LLD	Sum of auditory spectrum (loudness)	Relative minimum range
4	Prosodic	Energy related LLD	Zero crossing rate	Coefficient 0 of linear prediction
5	Cepstral	Spectral LLD	MFCC 1–14	Absolute peak range
6	Cepstral	Spectral LLD	MFCC 1–14	Relative peak mean
7	Spectral	Spectral LLD	Spectral Variance	Standard deviation of peak distances
8	Sound Quality	Voicing related LLD	Probability of voicing	Arithmetic mean
9	Prosodic	Energy related LLD	Zero crossing rate	Absolute peak range
10	Cepstral	Spectral LLD	MFCC 1–14	Absolute peak range
11	Cepstral	Spectral LLD	MFCC 1–14	99% percentile
12	Cepstral	Spectral LLD	MFCC 1–14	Range
13	Cepstral	Spectral LLD	MFCC 1–14	3rd coefficient of linear prediction
14	Prosodic	Energy Related LLD	RMS Energy	Relative peak range
15	Cepstral	Spectral LLD	MFCC 1–14	Inter-quartile 1–2
16	Cepstral	Spectral LLD	MFCC 1–14	Standard deviation of rising slope
17	Spectral	Spectral LLD	RASTA-PLP style auditory spectrum, bands 1–26 (0–8 kHz)	Absolute peak range
18	Cepstral	Spectral LLD	MFCC 1–14	Inter-quartile 1–2
19	Cepstral	Spectral LLD	MFCC 1–14	99% percentile
20	Prosodic	Energy Related LLD	Sum of auditory spectrum (loudness)	Centroid
21	Spectral	Spectral LLD	Spectral Flux	3rd coefficient of linear prediction
22	Prosodic	Voicing Related LLD	Fundamental frequency	Relative duration of the LLD is above 25%
23	Spectral	Spectral LLD	RASTA-PLP style auditory spectrum, bands 1–26 (0–8 kHz)	Relative peak mean
24	Cepstral	Spectral LLD	MFCC 1–14	Absolute peak range
25	Spectral	Spectral LLD	RASTA-PLP style auditory spectrum, bands 1–26 (0–8 kHz)	Mean of peak distances
26	Spectral	Spectral LLD	Spectral Skewness	Absolute peak range
27	Cepstral	Spectral LLD	MFCC 1–14	Absolute peak mean
28	Sound Quality	Voicing related LLD	Jitter (Delta/Derivative)	2nd coefficient of linear prediction
29	Spectral	Spectral LLD	Spectral variance	Relative peak range
30	Cepstral	Spectral LLD	MFCC 1–14	2nd coefficient of linear prediction

C, the whole group of controls; PWS, the whole group of people with stuttering; LLD, low level descriptor, MFCC, mel-frequency spectral coefficients; RASTA-PLP, relative spectral transform-perceptual linear prediction.