A phonetic basis for the sonority of [X]

Although after voiceless stops French rhotics are realized as voiceless uvular fricatives [Х], they pattern phonologically as high-sonority liquids and are the only obstruent allowed between a consonant and a vowel. This poses a problem for the sonority hierarchy. This experiment tests whether [Х], which has apparent approximant-like formant structure (Yeou and Maeda, 1995) patterns like the fricative [f] or the approximant [l] in its ability to convey information in formant transitions from a preceding consonant. In an AX burst detection task, native English speakers heard syllables of the form ClV, CХV, and CfV (spoken by a native French speaker) with and without a burst. Pilot data (n = 8; 410 trials each) suggests participants are more likely to respond “same” for [Х] and [l] trials than for [f] trials (p < 0.001), suggesting that [Х] carries more redundant information from a preceding consonant than [f] does and thus behaves more like approximants than other fricatives do. This suggests that the sonority of [Х] is grounded in acoustics and perception, rendering an abstract account of sonority unnecessary. This result predicts that other fricatives with long front cavities should also be able to function as high-sonority segments.