Processing complex sentences in fluctuating noise: Intelligibility vs. cognitive resources
Rebecca Carroll & Esther Ruigendijk, University of Oldenburg
Processing speech in adverse listening conditions (e.g. background noise) has been shown to be more
difficult than in acoustically well-controlled settings (Uslar et al. 2010, Carroll & Ruigendijk, subm.).
Yet, fluctuating noise has been shown to increase intelligibility as compared to stationary noise, since
silent intervals can be used for contextual information, which can make up for information ‘lost’ in noise
(Wagener, Brand & Kollmeier 2006). However, we know little about the processing mechanisms
involved in fluctuating noise. It is possible that it interacts with syntactic complexity, as noise itself adds
load to working memory, which is also needed for difficult sentences (cf. Carroll & Ruigendijk, subm.).
We tested sentences of different complexity at three different measuring points in a reaction time
study. Each trial was followed by a comprehension task. All stimuli were presented in fluctuating noise.
Our material consists of V2 sentences (SVO, OVS) and embedded relative clauses (subject & object
relatives), with or without canonical word order and with or without ambiguity. We also tested several
cognitive measures to account for interindividual differences of the 21 normal-hearing native German
Results show canonicity effects for OVS and reanalysis effects for ambiguous OVS sentences.
Surprisingly, object relatives do not clearly show comparable structural effects. However, subdivision of
participants shows that listeners who reached the correct interpretation do show canonicity effects, but
listeners with below chance-level performance do not. We interpret this finding as a sign of shallow
processing, which obscures the overall effects.
We also observe different processing mechanisms between SVO/OVS sentences and relative clauses.
While the former strongly co-vary with the word span measure, the latter co-vary with the Stroop measure
(indicative of susceptibility to interference). We argue for an interaction of bottom-up and top-down
processes involved in processing complex sentences in fluctuating noise (intelligibility vs. higher-level
processing and involvement of cognitive measures), which not only depend on the structural and
acoustical make-up of the sentence but also on the characteristics of the interfering noise. While
fluctuating noise may facilitate intelligibility (as compared to stationary noise as reported by Carroll &
Ruigendijk, subm.) on an acoustic level, it can have a negative influence on structural processing on
higher cognitive levels. That is, the relevant informational cues of a given structure are different and may
thus be affected to different degrees. Parts of the processing of SVO/OVS sentences can be related to
working memory, processing difficulties in relative clauses depends more on the susceptibility to