title: Amplitude modulation of turbulence noise by voicing in fricatives.
abstract: The two principal sources of sound in speech, voicing and frication, occur simultaneously in voiced fricatives as well as at the vowel-fricative boundary in phonologically voiceless fricatives. Instead of simply overlapping, the two sources interact. This paper is an acoustic study of one such interaction effect: the amplitude modulation of the frication component when voicing is present. Corpora of sustained and fluent-speech English fricatives were recorded and analyzed using a signal-processing technique designed to extract estimates of modulation depth. Results reveal a pattern, consistent across speaking style, speaker, and place of articulation, for modulation at fo to rise at low voicing strengths and subsequently saturate. Voicing strength needed to produce saturation varied 60-66 dB across subjects and experimental conditions. Modulation depths at saturation varied little across speakers but significantly for place of articulation (with [z] showing particularly strong modulation) clustering at approximately 0.4-0.5 (a 40%-50% fluctuation above and below unmodulated amplitude); spectral analysis of modulating signals revealed weak but detectable modulation at the second and third harmonics (i.e., 2fo and 3fo).
authors.affiliation: Centre for Vision, Speech & Signal Processing, University of Surrey, Guildford, GU2 7XH, United Kingdom. j.pincas@surrey.ac.uk
authors.forename: Jonathan
authors.initials: J
authors.lastname: Pincas
authors.forename: Philip J B
authors.initials: PJ
authors.lastname: Jackson
mesh_terms: D006801:Humans; D008954:Models, Biological; D009622:Noise; D010699:Phonation / Q000502:physiology*; D010700:Phonetics; D014831:Voice