Lexically Mediated Compensation for Coarticulation Still as Elusive as a White Christmash.

Luthra, Peraza-Santiago, Beeson, Saltzman, Crinnion, and Magnuson (2021) present data from the lexically mediated compensation for coarticulation paradigm that they claim provides conclusive evidence in favor of top-down processing in speech perception. We argue here that this evidence does not support that conclusion. The findings are open to alternative explanations, and we give data in support of one of them (that there is an acoustic confound in the materials). Lexically mediated compensation for coarticulation thus remains elusive, while prior data from the paradigm instead challenge the idea that there is top-down processing in online speech recognition.

Selective adaptation of German /r/: A role for perceptual saliency.

In three experiments, we examined selective adaptation of German /r/ depending on the positional and allophonic overlap between adaptors and targets. A previous study had shown that selective adaptation effects with /r/ in Dutch require allophonic overlap between adaptor and target. We aimed at replicating this finding in German, which also has many allophones of /r/. German post-vocalic /r/ is often vocalized, and pre-vocalic /r/ can occur in at least three forms: uvular fricative [ʁ], uvular trill [ʀ] and alveolar trill [r]. We tested selective adaptation between these variants. The critical questions were whether an allophonic overlap is necessary for adaptation or whether phonemic overlap is sufficient to generate an adaptation effect. Surprisingly, our results show that both assertations are wrong: Adaptation does not require an allophonic overlap between adaptors and target and neither is phonemic overlap sufficient. Even more surprisingly, trilled adaptors led to more adaptation for a uvular-fricative target than uvular-fricative adaptors themselves. We suggest that the perceptual salience of the adaptors may be a hitherto underestimated influence on selective adaptation.

Glottal stops do not constrain lexical access as do oral stops.

This study explores processing characteristics of a glottal stop in Maltese which occurs both as a phoneme and as an epenthetic stop for vowel-initial words. Experiment 1 shows that its hyperarticulation is not necessarily mapped onto an underlying form, although listeners may interpret it as underlying at a later processing stage. Experiment 2 shows that listeners' experience with a particular speaker's use of a glottal stop exclusively as a phoneme does not modulate competition patterns accordingly. Not only are vowel-initial words activated by [ʔ]-initial forms, but /ʔ/-initial words are also activated by vowel-initial forms, suggesting that lexical access is not constrained by an initial acoustic mismatch that involves a glottal stop. Experiment 3 reveals that the observed pattern is not generalizable to an oral stop /t/. We propose that glottal stops have a special status in lexical processing: it is prosodic in nature to be licensed by the prosodic structure.

The Role of Segmental Information in Syntactic Processing Through the Syntax-Prosody Interface.

In two experiments, it was investigated whether potentially contrastive segmental information in the form of an epenthetic glottal stop in Maltese can influence syntactic parsing decisions. The glottal stop in Maltese serves a dual function as a phoneme used for lexical contrast and a non-contrastive phone that may mark a prosodic juncture. In both experiments, participants perceived a larger prosodic boundary before the word u (Engl. "and") if the u was produced with an epenthetic glottal stop, showing the use of prosodically conditioned segmental information in syntactic parsing. Furthermore, listeners were generally unaware of the existence of the epenthetic glottal stop even though a glottal stop is used as a phoneme represented as a grapheme "q." They also perceived a larger prosodic juncture when the preceding syllable was lengthened before the word u ("and"). These findings were consistent regardless of whether the glottal stop reinforced a late-closure decision (Experiment 1) or an early-closure decision (Experiment 2). The results indicate that both segmental and suprasegmental information influences syntactic parsing decisions, demonstrating that the syntax-prosody interface is reflected along both the segmental and suprasegmental (duration) dimensions, which are mediated by the phonetics-prosody interface.

Datasets on the production and perception of underlying and epenthetic glottal stops in Maltese.

This article provides some supplementary analysis data of speech production and perception of glottal stops in the Semitic language Maltese. In Maltese, a glottal stop can occur as a phoneme, but also as a phonetic marker of vowel-initial words (as in the case with Germanic languages like English). Data from four experiments are provided, which will allow other researchers to reproduce the results and apply their own data-analysis techniques to these data for further data exploration. A production experiment (Experiment 1) investigates how often the glottal marking of vowel-initial words occurs (causing vowel-initial words to be ambiguous with words starting with a glottal stop as a phoneme) and whether the glottal gesture for this marking can be differentiated from an underlying (phonemic) glottal stop in its acoustic properties. Experiments 2 to 4 investigate how and to what extent Maltese listeners perceive glottal markings as lexical (phonemic) or epenthetic (phonetic), using a two-alternative forced choice task (Experiment 2), a visual-world eye tracking task with printed target words (Experiment 3) and a gating task (Experiment 4). A full account of theoretical consequences of these data can be found in the full length article entitled "The glottal stop between segmental and suprasegmental processing: The case of Maltese" [1].

My English sounds better than yours: Second-language learners perceive their own accent as better than that of their peers.

Second language (L2) learners are often aware of the typical pronunciation errors that speakers of their native language make, yet often persist in making these errors themselves. We hypothesised that L2 learners may perceive their own accent as closer to the target language than the accent of other learners, due to frequent exposure to their own productions. This was tested by recording 24 female native speakers of German producing 60 sentences. The same participants later rated these recordings for accentedness. Importantly, the recordings had been altered to sound male so that participants were unaware of their own productions in the to-be-rated samples. We found evidence supporting our hypothesis: participants rated their own altered voice, which they did not recognize as their own, as being closer to a native speaker than that of other learners. This finding suggests that objective feedback may be crucial in fostering L2 acquisition and reduce fossilization of erroneous patterns.

A time course of prosodic modulation in phonological inferencing: The case of Korean post-obstruent tensing.

Application of a phonological rule is often conditioned by prosodic structure, which may create a potential perceptual ambiguity, calling for phonological inferencing. Three eye-tracking experiments were conducted to examine how spoken word recognition may be modulated by the interaction between the prosodically-conditioned rule application and phonological inferencing. The rule examined was post-obstruent tensing (POT) in Korean, which changes a lax consonant into a tense after an obstruent only within a prosodic domain of Accentual Phrase (AP). Results of Experiments 1 and 2 revealed that, upon hearing a derived tense form, listeners indeed recovered its underlying (lax) form. The phonological inferencing effect, however, was observed only in the absence of its tense competitor which was acoustically matched with the auditory input. In Experiment 3, a prosodic cue to an AP boundary (which blocks POT) was created before the target using an F0 cue alone (i.e., without any temporal cues), and the phonological inferencing effect disappeared. This supports the view that phonological inferencing is modulated by listeners' online computation of prosodic structure (rather than through a low-level temporal normalization). Further analyses of the time course of eye movement suggested that the prosodic modulation effect occurred relatively later in the lexical processing. This implies that speech processing involves segmental processing in conjunction with prosodic structural analysis, and calls for further research on how prosodic information is processed along with segmental information in language-specific vs. universally applicable ways.

Visual speech influences speech perception immediately but not automatically.

Two experiments examined the time course of the use of auditory and visual speech cues to spoken word recognition using an eye-tracking paradigm. Results of the first experiment showed that the use of visual speech cues from lipreading is reduced if concurrently presented pictures require a division of attentional resources. This reduction was evident even when listeners' eye gaze was on the speaker rather than the (static) pictures. Experiment 2 used a deictic hand gesture to foster attention to the speaker. At the same time, the visual processing load was reduced by keeping the visual display constant over a fixed number of successive trials. Under these conditions, the visual speech cues from lipreading were used. Moreover, the eye-tracking data indicated that visual information was used immediately and even earlier than auditory information. In combination, these data indicate that visual speech cues are not used automatically, but if they are used, they are used immediately.

How does cognitive load influence speech perception? An encoding hypothesis.

Two experiments investigated the conditions under which cognitive load exerts an effect on the acuity of speech perception. These experiments extend earlier research by using a different speech perception task (four-interval oddity task) and by implementing cognitive load through a task often thought to be modular, namely, face processing. In the cognitive-load conditions, participants were required to remember two faces presented before the speech stimuli. In Experiment 1, performance in the speech-perception task under cognitive load was not impaired in comparison to a no-load baseline condition. In Experiment 2, we modified the load condition minimally such that it required encoding of the two faces simultaneously with the speech stimuli. As a reference condition, we also used a visual search task that in earlier experiments had led to poorer speech perception. Both concurrent tasks led to decrements in the speech task. The results suggest that speech perception is affected even by loads thought to be processed modularly, and that, critically, encoding in working memory might be the locus of interference.

Use what you can: storage, abstraction processes, and perceptual adjustments help listeners recognize reduced forms.

Three eye-tracking experiments tested whether native listeners recognized reduced Dutch words better after having heard the same reduced words, or different reduced words of the same reduction type and whether familiarization with one reduction type helps listeners to deal with another reduction type. In the exposure phase, a segmental reduction group was exposed to /b/-reductions (e.g., minderij instead of binderij, "book binder") and a syllabic reduction group was exposed to full-vowel deletions (e.g., p'raat instead of paraat, "ready"), while a control group did not hear any reductions. In the test phase, all three groups heard the same speaker producing reduced-/b/ and deleted-vowel words that were either repeated (Experiments 1 and 2) or new (Experiment 3), but that now appeared as targets in semantically neutral sentences. Word-specific learning effects were found for vowel-deletions but not for /b/-reductions. Generalization of learning to new words of the same reduction type occurred only if the exposure words showed a phonologically consistent reduction pattern (/b/-reductions). In contrast, generalization of learning to words of another reduction type occurred only if the exposure words showed a phonologically inconsistent reduction pattern (the vowel deletions; learning about them generalized to recognition of the /b/-reductions). In order to deal with reductions, listeners thus use various means. They store reduced variants (e.g., for the inconsistent vowel-deleted words) and they abstract over incoming information to build up and apply mapping rules (e.g., for the consistent /b/-reductions). Experience with inconsistent pronunciations leads to greater perceptual flexibility in dealing with other forms of reduction uttered by the same speaker than experience with consistent pronunciations.

Phonetic category recalibration: What are the categories?

Listeners use lexical or visual context information to recalibrate auditory speech perception. After hearing an ambiguous auditory stimulus between /aba/ and /ada/ coupled with a clear visual stimulus (e.g., lip closure in /aba/), an ambiguous auditory-only stimulus is perceived in line with the previously seen visual stimulus. What remains unclear, however, is what exactly listeners are recalibrating: phonemes, phone sequences, or acoustic cues. To address this question we tested generalization of visually-guided auditory recalibration to 1) the same phoneme contrast cued differently (i.e., /aba/-/ada/ vs. /ibi/-/idi/ where the main cues are formant transitions in the vowels vs. burst and frication of the obstruent), 2) a different phoneme contrast cued identically (/aba/-/ada/ vs. /ama/-/ana/ both cued by formant transitions in the vowels), and 3) the same phoneme contrast with the same cues in a different acoustic context (/aba/-/ada/ vs. (/ubu/-/udu/). Whereas recalibration was robust for all recalibration control trials, no generalization was found in any of the experiments. This suggests that perceptual recalibration may be more specific than previously thought as it appears to be restricted to the phoneme category experienced during exposure as well as to the specific manipulated acoustic cues. We suggest that recalibration affects context-dependent sub-lexical units.

Use of syntax in perceptual compensation for phonological reduction.

Listeners resolve ambiguity in speech by consulting context. Extensive research on this issue has largely relied on continua of sounds constructed to vary incrementally between two phonemic endpoints. In this study we presented listeners instead with phonetic ambiguity of a kind with which they have natural experience: varying degrees of word-final /t/-reduction. In two experiments, Dutch listeners decided whether or not the verb in a sentence such as Maar zij ren(t) soms 'But she sometimes run(s)' ended in /t/. In Dutch, presence versus absence of final /t/ distinguishes third- from first-person singular present-tense verbs. Acoustic evidence for /t/ varied from clear to absent, and immediately preceding phonetic context was consistent with more versus less likely deletion of /t/. In both experiments, listeners reported more /t/s in sentences in which /t/ would be syntactically correct. In Experiment 1, the disambiguating syntactic information preceded the target verb, as above, while in Experiment 2, it followed the verb. The syntactic bias was greater for fast than for slow responses in Experiment 1, but no such difference appeared in Experiment 2. We conclude that syntactic information does not directly influence pre-lexical processing, but is called upon in making phoneme decisions.

Phonological abstraction without phonemes in speech perception.

Recent evidence shows that listeners use abstract prelexical units in speech perception. Using the phenomenon of lexical retuning in speech processing, we ask whether those units are necessarily phonemic. Dutch listeners were exposed to a Dutch speaker producing ambiguous phones between the Dutch syllable-final allophones approximant [r] and dark [l]. These ambiguous phones replaced either final /r/ or final /l/ in words in a lexical-decision task. This differential exposure affected perception of ambiguous stimuli on the same allophone continuum in a subsequent phonetic-categorization test: Listeners exposed to ambiguous phones in /r/-final words were more likely to perceive test stimuli as /r/ than listeners with exposure in /l/-final words. This effect was not found for test stimuli on continua using other allophones of /r/ and /l/. These results confirm that listeners use phonological abstraction in speech perception. They also show that context-sensitive allophones can play a role in this process, and hence that context-insensitive phonemes are not necessary. We suggest there may be no one unit of perception.

Deviant neural processing of phonotactic probabilities in adults with dyslexia.

During language acquisition in the first year of life, children become sensitive to phonotactic probabilities such as the likelihood of speech sound occurrences in the ambient language. Because this sensitivity is acquired at an early age, the extent to which the neural system that underlies speech processing in adults is tuned to these phonological regularities can reflect difficulties in processing language-specific phonological regularities that can persist into adulthood. Here, we examined the neural processing of phonotactic probabilities in 18 adults with dyslexia and 18 non-dyslexic controls using mismatch negativity, a pre-attentive neurophysiological response. Stimuli that differed in phonotactic probability elicited similar mismatch negativity responses among the adults with dyslexia, whereas the controls responded more strongly to stimuli with a high phonotactic probability than to stimuli with a low phonotactic probability, suggesting that controls - but not adults with dyslexia - are sensitive to the phonological regularities of the ambient language. These findings suggest that the underlying neural system in adults with dyslexia is not properly tuned to language-specific phonological regularities, which may partially account for the phonological deficits that are often reported in dyslexic individuals.

Regional accent variation in the shadowing task: evidence for a loose perception-action coupling in speech.

We investigated the relation between action and perception in speech processing, using the shadowing task, in which participants repeat words they hear. In support of a tight perception-action link, previous work has shown that phonetic details in the stimulus influence the shadowing response. On the other hand, latencies do not seem to suffer if stimulus and response differ in their articulatory properties. The present investigation tested how perception influences production when participants are confronted with regional variation. Results showed that participants often imitate a regional variation if it occurs in the stimulus set but tend to stick to their variant if the stimuli are consistent. Participants were forced or induced to correct by the experimental instructions. Articulatory stimulus-response differences do not lead to latency costs. These data indicate that speech perception does not necessarily recruit the production system.

Evidence for precategorical extrinsic vowel normalization.

Three experiments investigated whether extrinsic vowel normalization takes place largely at a categorical or a precategorical level of processing. Traditional vowel normalization effects in categorization were replicated in Experiment 1: Vowels taken from an [I]-[ε] continuum were more often interpreted as /I/ (which has a low first formant, F(1)) when the vowels were heard in contexts that had a raised F(1) than when the contexts had a lowered F(1). This was established with contexts that consisted of only two syllables. These short contexts were necessary for Experiment 2, a discrimination task that encouraged listeners to focus on the perceptual properties of vowels at a precategorical level. Vowel normalization was again found: Ambiguous vowels were more easily discriminated from an endpoint [ε] than from an endpoint [I] in a high-F(1) context, whereas the opposite was true in a low-F(1) context. Experiment 3 measured discriminability between pairs of steps along the [I]-[ε] continuum. Contextual influences were again found, but without discrimination peaks, contrary to what was predicted from the same participants' categorization behavior. Extrinsic vowel normalization therefore appears to be a process that takes place at least in part at a precategorical processing level.

Listeners retune phoneme categories across languages.

Native listeners adapt to noncanonically produced speech by retuning phoneme boundaries by means of lexical knowledge. We asked whether a second language lexicon can also guide category retuning and whether perceptual learning transfers from a second language (L2) to the native language (L1). During a Dutch lexical-decision task, German and Dutch listeners were exposed to unusual pronunciation variants in which word-final /f/ or /s/ was replaced by an ambiguous sound. At test, listeners categorized Dutch minimal word pairs ending in sounds along an /f/-/s/ continuum. Dutch L1 and German L2 listeners showed boundary shifts of a similar magnitude. Moreover, following exposure to Dutch-accented English, Dutch listeners also showed comparable effects of category retuning when they heard the same speaker speak her native language (Dutch) during the test. The former result suggests that lexical representations in a second language are specific enough to support lexically guided retuning, and the latter implies that production patterns in a second language are deemed a stable speaker characteristic likely to transfer to the native language; thus retuning of phoneme categories applies across languages.

How phonological reductions sometimes help the listener.

In speech production, high-frequency words are more likely than low-frequency words to be phonologically reduced. We tested in an eye-tracking experiment whether listeners can make use of this correlation between lexical frequency and phonological realization of words. Participants heard prefixed verbs in which the prefix was either fully produced or reduced. Simultaneously, they saw a high-frequency verb and a low-frequency verb with this prefix-plus 2 distractors-on a computer screen. Participants were more likely to look at the high-frequency verb when they heard a reduced prefix than when they heard a fully produced prefix. Listeners hence exploit the correlation of lexical frequency and phonological reduction and assume that a reduced prefix is more likely to belong to a high-frequency word. This shows that reductions do not necessarily burden the listener but may in fact have a communicative function, in line with functional theories of phonology.