Acoustic Analysis of the Uvular Unvoiced Fricative

An acoustic analysis of the uvular unvoiced fricative in intervocalic sequences, as spoken in Arabic, is presented. Properties of both the noise region and voiced boundaries are examined, and several attributes are discovered: the glottal waveform changes considerably during its transition between the vowels and the fricative boundaries, with the open quotient becoming 100% at the boundaries compared to around 50% at the neighboring vowels; the noise region in the unvoiced fricative exhibits an underlying periodic pattern with a frequency of vibration of around 90Hz; the directions of formant trajectories into the fricative are highly dependent on the intervocalic context and different from predictions of articulatory-acoustic models for most cases; the turbulence noise strongly excites the first formant, in addition to the expected second formant. All these results form the basis for determining perceptual cues, developing aerodynamic models and acoustic models, and building high quality formant synthesizers.