| The acoustic characteristics of fricatives were investigated with the aim of finding invariant cues that classify fricatives into their place of articulation. However, such invariant cues are hard to recognize because of the long-noticed problem of variability in the acoustic signal. Both intrinsic and extrinsic sources of variability in the speech signal lead to a defective match between a signal and its percept. Nevertheless, such invariance can be circumvented by using appropriate analysis methods. The 13 fricatives of Modern Standard Arabic (/f, theta, th, th[special character omitted], s, s[special character omitted], z, ∫, chi, [special character omitted], h, [special character omitted], h/) were elicited from 8 male adult speakers in 6 vowel contexts (/i, i[special character omitted], a, a[special character omitted], u, u[special character omitted]/). The acoustic cues investigated included amplitude measurements (normalized and relative frication noise amplitude), spectral measurements (spectral peak location and spectral moments), temporal measurements (absolute and normalized frication noise duration); and formant information at fricative-vowel transition (F2 at vowel onset and locus equation). For the most part, fricatives in Arabic had patterns similar to those reported for similar fricatives in other languages (e.g., English, Spanish, Portuguese). A discriminant function analysis showed that among all the cues investigated, spectral mean, skewness, second formant at vowel onset, normalized RMS amplitude, relative amplitude, and spectral peak location were the variables contributing the most to overall classification with a success rate of 83.2%. When voicing was specified in the model, the correct classification rate increased to 92.9% for voiced and 93.5% for voiceless fricatives. |
