On the perception of \u201csegmental intonation\u201d: F0 context effects on sibilant identification in German

Oliver Niebuhr

doi:10.1186/s13636-017-0115-3

Abstract

In normal modally voiced utterances, voiceless fricatives like [s], [ʃ], [f], and [x] vary such that their aperiodic pitch impressions mirror the pitch level of the adjacent F0 contour. For instance, if the F0 contour creates a high or low pitch context, then the aperiodic pitch impression of the fricative in this context will also be high or low. This context-matching effect has been termed “segmental intonation”. While there is accumulating evidence for segmental intonation in speech production, less is known about if and how segmental intonation is actually integrated in the perception of utterance tunes. This question is addressed here in a perception experiment in which listeners identified target words ending in either [ʃ] or [s]. The two sibilants inherently create low or high aperiodic pitch impressions in listeners due to their characteristically different spectral energy distributions. The sibilants were preceded by high or low F0 contexts in the target words. Results show a clear F0-context effect. The context effect triggered more [ʃ] identifications in high-F0 and/or more [s] identifications in low-F0 contexts. The effect was larger for sibilants that were less clearly identifiable as either /ʃ/ or /s/. The effect represents strong supporting evidence that listeners in fact perceive the segmental intonation of fricatives and integrate its aperiodic pitch with the F0-based pitch when perceiving utterance intonation. Thus, the term “segmental intonation” is perceptually appropriate. Furthermore, the results are discussed with respect to reaction-time measurements and an additional effect of the quality of the adjacent vowel phoneme on sibilant identification.

Highlights

1.1 Background: the notion of “segmental intonation” Studying intonation, be it for phonological or technical purposes, focuses on the primary acoustic correlate of perceived pitch: the fundamental frequency (F0)
Higashikawa [11] and Higashikawa and Minifie [12] added to this picture that sibilant pitch perception—or “whisper pitch” in the terminology of Higashikawa and colleagues—is independent of the listener’s linguistic or phonological background and that simultaneous changes in F1 and higher formants like F2 are more effective in changing sibilant pitch than changes in F1 or F2 alone
Sibilants 1–2 were identified as instances of [ʃ] in more than 95% of all target words

Summary

Introduction

1.1 Background: the notion of “segmental intonation” Studying intonation, be it for phonological or technical purposes, focuses on the primary acoustic correlate of perceived pitch: the fundamental frequency (F0). This focus on F0 is, well justified and allowed speech scientists of the past decades to accumulate considerable knowledge of the syntagmatic structure of intonational tunes and the forms and functions of melodic elements at each structural position in the syntagma (for German, cf [1,2,3,4,5]). The sibilant pitch perceived for voiceless front vowels (i.e. variants of the voiceless fricative [h]) is determined by the vowels’ second formant frequency (F2) and subsequent higher formants in the spectral energy pattern. Higashikawa [11] and Higashikawa and Minifie [12] added to this picture that sibilant pitch perception—or “whisper pitch” in the terminology of Higashikawa and colleagues—is independent of the listener’s linguistic or phonological background and that simultaneous changes in F1 and higher formants like F2 are more effective in changing sibilant pitch than changes in F1 or F2 alone

Methods

Results

Conclusion