The role of stimulus cross-splicing in an event-related potentials study. Misleading formant transitions hinder automatic phonological processing

Abstract

The mental organization of linguistic knowledge and its involvement in speech processing can be investigated using the mismatch negativity (MMN) component of the auditory event-related potential. A contradiction arises, however, between the technical need for strict control of acoustic stimulus properties and the quest for naturalness and acoustic variability of the stimuli. Here, two methods of preparing speech stimulus material were compared. Focussing on the automatic processing of a phonotactic restriction in German, two corresponding sets of various vowel-fricative syllables were used as stimuli. The former syllables were naturally spoken while the latter ones were created by means of cross-splicing. Phonetically, natural and spliced syllables differed with respect to the appropriateness of coarticulatory information about the forthcoming fricative within the vowels. Spliced syllables containing clearly misleading phonetic information were found to elicit larger N2 responses compared to their natural counterparts. Furthermore, MMN results found for the natural syllables could not be replicated with these spliced stimuli. These findings indicate that the automatic processing of the stimuli was considerably affected by the stimulus preparation method. Thus, in spite of its unquestioned benefits for MMN experiments, the splicing technique may lead to interference effects on the linguistic factors under investigation.

Laryngeal Features Are Phonetically Abstract: Mismatch Negativity Evidence from Arabic, English, and Russian

“…There were no surrounding vowels for any tokens. The use of naturally produced fricatives in isolation mirrors previous studies using vowels (Cornell et al, 2011; de Jonge and Boersma, 2015) and also eliminates any possible effects of coarticulation or phonotactic knowledge (Bonte et al, 2005), or cross-splicing (Steinberg et al, 2012), and has been successfully used in previous experiments (Schluter et al, 2016). For each type, six distinct tokens were selected by a trained phonetician.…”

M/EEG analysis of naturalistic stories: a review from speech to language processing

“…Alday, Schlesewsky, & Bornkessel-Schlesewsky, 2017) and paralinguistic (Tromp, Peeters, Meyer, & Hagoort, 2017), matter as well as their constant, continuous overlap (cf. Steinberg, Truckenbrodt, & Jacobsen, 2012, who found that stimulus splicing and the resultant misleading formant transitions impact phonological processing). In the following, we present results from our search and not the more fundamental, original results from non-naturalistic studies.…”

“…This again has its parallel in the traditional ERP literature, where the usual exogenous components -N1, etc.are visible at the start of the auditory stimulation, even if that is rarely a critical position. This type of "gap splicing" can be somewhat problematic (Steinberg et al, 2012) when studying phonological processing because it removes co-articulation; however, here it is less problematic as the speech envelope and not the role of any particular phoneme or higher processing was the object of interest. Kayser and colleagues found no effect of the speech rate manipulation, although the amplitude of the evoked potential did increase with the duration of pause, regardless of overall speech rate.…”

Predictive coding of phonological rules in auditory cortex: A mismatch negativity study

“…The above mentioned phonological MMN studies (e.g., Steinberg et al, 2010aSteinberg et al, , 2010bSteinberg et al, , 2011, however, share the feature of exploring adjacent phonemes that have different phonotactical co-occurrence probabilities. As a result, the possibility that MMN is affected by the co-occurrence probabilities of adjacent sounds (Bonte, Mitterer, Zellagui, Poelmans, & Blomert, 2005) or co-articulatory cues (Steinberg, Truckenbrodt, & Jacobsen, 2012) is difficult to rule out entirely. A study design tapping the application of phonological rules on non-adjacent phonemes would help to tease apart acousticphonetic and abstract rule-based effects on MMN, because non-adjacent phonemes should be less prone to the effects of co-occurrence probabilities and co-articulation.…”