Human Speech Perception Research Articles

Temporal fine structure and zebra finch vocalizations

The temporal fine structure (TFS) of an acoustic signal refers to the smaller changes within the time waveform, independent of larger envelope changes. Bioacousticians typically have relied on sonographic analyses to describe the primary acoustic features of animal vocalizations and human speech. However, sonographic analyses do not reveal the temporal fine structure in complex vocal signals. Recent research on the perception of human speech by normal-hearing and hearing-impaired listeners has suggested that TFS is important for speech comprehension. Interestingly, birds have much better sensitivity to changes in TFS than do humans, suggesting TFS could also be important for communication in birds. TFS in complex signals is extremely difficult to study in isolation since it occurs along with other acoustic features of complex signals. But, here using a variety of techniques to reduce or eliminate other acoustic features of a complex acoustic signal, we show that zebra finches have particularly good perceptual sensitivity to the natural variation in TFS, and that there are very likely systematic differences in TFS that are unique to various classes of vocal signals. These results suggest that, as with human speech, TFS may be important in avian acoustic communication.

Catching a rabbit with a tetrahedron: A contextualist approach

A defining characteristic of Jim Jenkins’ long and productive research career was his ability to reconcile contradictory experimental evidence within a coherent conceptual framework that leads to novel insights and experimental approaches. Grounded in the deep knowledge of history of psychology, Jim’s involvement and expertise in different aspects of human behavior, including language, speech, memory, attention, visual, and auditory perception, resulted in important theoretical breakthroughs (and countless stimulating discussions). One such work is the tetrahedral model of memory experiments. It considers four large clusters of experimental variables: subjects, materials, scoring tasks, and testing procedures, whose mutual interactions determine experimental outcomes. [J.J. Jenkins “Four points to remember: A tetrahedral model of memory experiments,” in Levels of Processing in Human Memory, ed. LS Cermak, FIM Craik, (1979)]. Initially proposed to account for inconsistent findings of memory experiments, the model's applications have expanded to other areas of perceptual training and education as a guide to maximize learning outcomes. Following Jim’s lead, I will illustrate how the tetrahedral model can (1) improve the understanding of research findings from two ecologically significant sound classes, speech and environmental sounds, in normal hearing and cochlear implant listeners, and (2) guide the design of effective auditory training programs.

Effects of training on the perception of talker information in degraded speech

A fundamental property of human speech perception is its robustness in a wide range of listening conditions. Listeners are able to successfully recognize and understand speech under a wide range of adverse and challenging conditions, such as in noise, reverberation, or multi-talker babble, and with noise vocoding. Noise vocoding, a manipulation that reduces spectral resolution, has been shown to result in less accurate speech comprehension and also poorer perception of indexical information (e.g., talkers’ voices). However, speech comprehension quickly improves with exposure, as listeners learn to better extract information from the systematically degraded speech. The extent to which the learning of noise-vocoded speech transfers to other talkers or tasks is still largely unknown. The current study investigated whether training, consisting of transcribing sentences or identifying talkers’ voices from sentences, leads to improvements in the perception of talker information. Preliminary results suggest that both training tasks resulted in improved perception of talker information, as participants learned general information about the degradation. Larger improvements were observed after talker identification training, which focused attention on talker differences. Differences between training tasks, and implications for cochlear implant users, will be discussed. [Funding: VENI Grant (275.89.035) from the Netherlands Organization for Scientific Research (NWO).]

Vocal Tract Length Normalization

The resonant frequencies of the vocal tract during vowel production convey information about the linguistic vowel intended by the talker - whether they mean to say ‘hey’ or ‘hoe’, for example - while also conveying information about the talker. One particularly salient bit of talker information that partially determines the frequencies of the vowel formants is the length of the talker’s vocal tract. Vowel formant normalization aims to remove the effects of talker differences without also removing important linguistic information. This paper presents a study of vocal tract length normalization using a new ΔF method, and compares this method to other vowel normalization methods. A key point of comparison in this study is the number of vowel tokens that are needed in order to derive a stable estimate of vocal tract length. Several of the vowel normalization methods that are most commonly used in phonetic studies are shown to need a full set of vowels in order to be reliable, while methods that derive vocal tract length information from the full acoustic spectrum are much more stable and may even provide a length-normalized representation that could be cognitively computed and used in human speech perception.

Selecting frames for automatic speech recognition based on acoustic landmarks

Most mainstream Mel-frequency cepstral coefficient (MFCC) based Automatic Speech Recognition (ASR) systems consider all feature frames equally important. However, the acoustic landmark theory disagrees with this idea. Acoustic landmark theory exploits the quantal non-linear articulatory-acoustic relationships from human speech perception experiments and provides a theoretical basis of extracting acoustic features in the vicinity of landmark regions where an abrupt change occurs in the spectrum of speech signals. In this work, we conducted experiments, using the TIMIT corpus, on both GMM and DNN based ASR systems and found that frames containing landmarks are more informative than others during the recognition process. We proved that altering the level of emphasis on landmark and non-landmark frames, through re-weighting or removing frame acoustic likelihoods accordingly, can change the phone error rate (PER) of the ASR system in a way dramatically different from making similar changes to random frames. Furthermore, by leveraging the landmark as a heuristic, one of our hybrid DNN frame dropping strategies achieved a PER increment of 0.44% when only scoring less than half, 41.2% to be precise, of the frames. This hybrid strategy out-performs other non-heuristic-based methods and demonstrated the potential of landmarks for computational reduction for ASR.

New Methods for Prosodic Transcription: Capturing Variability as a Source of Information

Understanding the role of prosody in encoding linguistic meaning and in shaping phonetic form requires the analysis of prosodically annotated speech drawn from a wide variety of speech materials. Yet obtaining accurate and reliable prosodic annotations for even small datasets is challenging due to the time and expertise required. We discuss several factors that make prosodic annotation difficult and impact its reliability, all of which relate to variability : in the patterning of prosodic elements (features and structures) as they relate to the linguistic and discourse context, in the acoustic cues for those prosodic elements, and in the parameter values of the cues. We propose two novel methods for prosodic transcription that capture variability as a source of information relevant to the linguistic analysis of prosody. The first is Rapid Prosody Transcription (RPT), which can be performed by non-experts using a simple set of unary labels to mark prominence and boundaries based on immediate auditory impression. Inter-transcriber variability is used to calculate continuous-valued prosody ‘scores’ that are assigned to each word and represent the perceptual salience of its prosodic features or structure. RPT can be used to model the relative influence of top-down factors and acoustic cues in prosody perception, and to model prosodic variation across many dimensions, including language variety,speech style, or speaker’s affect. The second proposed method is the identification of individual cues to the contrastive prosodic elements of an utterance. Cue specification provides a link between the contrastive symbolic categories of prosodic structures and the continuous-valued parameters in the acoustic signal, and offers a framework for investigating how factors related to the grammatical and situational context influence the phonetic form of spoken words and phrases. While cue specification as a transcription tool has not yet been explored as RPT has, it has the potential to provide a level of detail that will be useful in modelling systematic context-governed variation in the implementation of prosodic categories, with applications in automatic speech synthesis and recognition, as well as modelling human speech production and perception. We discuss how RPT and cue specification, particularly when combined, can improve the efficiency and reliability of prosodic transcription and how they can be integrated with expert phonological transcription.

Information transmission analysis for continuous speech features

Acoustic features are important for the study of human speech perception and the development of computational speech classification algorithms. These areas can benefit from a technique that accurately quantifies the information content of an individual feature, as well as the degree to which this information is used by a listener or algorithm. Feature information transmission analysis (FITA) was developed to do this for categorical features, but complications arise when applying it to continuous features. Absolute information measures are bounded from above by values substantially lower than their theoretical maxima, the precision with which a feature is produced is ignored and a tedious manual step is introduced into the analysis process. This article presents an alternative approach (the continuous FITA) that addresses these complications effectively by representing continuous features in a more natural way. It is shown that this approach is well-suited to continuous feature information analysis and, furthermore, can be used to estimate redundancy in multiple features and information transmitted by combinations of features. The continuous FITA can quantify information in extracted features before an identification experiment has been conducted. It can aid in feature selection for computational speech classification systems, measure feature utilization by humans as well as computational algorithms and facilitate the investigation of the effect of noise or signal processing on feature information.

What you see isn’t always what you get: Auditory word signals trump consciously perceived words in lexical access

Human speech perception often includes both an auditory and visual component. A conflict in these signals can result in the McGurk illusion, in which the listener perceives a fusion of the two streams, implying that information from both has been integrated. We report two experiments investigating whether auditory–visual integration of speech occurs before or after lexical access, and whether the visual signal influences lexical access at all. Subjects were presented with McGurk or Congruent primes and performed a lexical decision task on related or unrelated targets. Although subjects perceived the McGurk illusion, McGurk and Congruent primes with matching real-word auditory signals equivalently primed targets that were semantically related to the auditory signal, but not targets related to the McGurk percept. We conclude that the time course of auditory–visual integration is dependent on the lexicality of the auditory and visual input signals, and that listeners can lexically access one word and yet consciously perceive another.

Human Frequency Following Response

Listeners with sensorineural hearing loss (SNHL) typically experience reduced speech perception, which is not completely restored with amplification. This likely occurs because cochlear damage, in addition to elevating audiometric thresholds, alters the neural representation of speech transmitted to higher centers along the auditory neuroaxis. While the deleterious effects of SNHL on speech perception in humans have been well-documented using behavioral paradigms, our understanding of the neural correlates underlying these perceptual deficits remains limited. Using the scalp-recorded frequency following response (FFR), the authors examine the effects of SNHL and aging on subcortical neural representation of acoustic features important for pitch and speech perception, namely the periodicity envelope (F0) and temporal fine structure (TFS; formant structure), as reflected in the phase-locked neural activity generating the FFR. FFRs were obtained from 10 listeners with normal hearing (NH) and 9 listeners with mild-moderate SNHL in response to a steady-state English back vowel /u/ presented at multiple intensity levels. Use of multiple presentation levels facilitated comparisons at equal sound pressure level (SPL) and equal sensation level. In a second follow-up experiment to address the effect of age on envelope and TFS representation, FFRs were obtained from 25 NH and 19 listeners with mild to moderately severe SNHL to the same vowel stimulus presented at 80 dB SPL. Temporal waveforms, Fast Fourier Transform and spectrograms were used to evaluate the magnitude of the phase-locked activity at F0 (periodicity envelope) and F1 (TFS). Neural representation of both envelope (F0) and TFS (F1) at equal SPLs was stronger in NH listeners compared with listeners with SNHL. Also, comparison of neural representation of F0 and F1 across stimulus levels expressed in SPL and sensation level (accounting for audibility) revealed that level-related changes in F0 and F1 magnitude were different for listeners with SNHL compared with listeners with NH. Furthermore, the degradation in subcortical neural representation was observed to persist in listeners with SNHL even when the effects of age were controlled for. Overall, our results suggest a relatively greater degradation in the neural representation of TFS compared with periodicity envelope in individuals with SNHL. This degraded neural representation of TFS in SNHL, as reflected in the brainstem FFR, may reflect a disruption in the temporal pattern of phase-locked neural activity arising from altered tonotopic maps and/or wider filters causing poor frequency selectivity in these listeners. Finally, while preliminary results indicate that the deleterious effects of SNHL may be greater than age-related degradation in subcortical neural representation, the lack of a balanced age-matched control group in this study does not permit us to completely rule out the effects of age on subcortical neural representation.

자극음의 음향적 특성과 청각 뇌간에서의 전기생리학적 반응의 상관성

청각기관의 음조체계로 인해 사람들은 일반적으로 주파수 분포에 따라 소리를 듣는다. 그러나 어음인지 측면에서 어음의 음향적 특성이 사람의 뇌에서 어떻게 인식되는지는 여전히 명확하지 않다. 따라서 본 연구에서는 유사한 고주파수 음향적 특성을 갖는 두 개의 어음이 청각 뇌간에서 전기생리학적으로 어떻게 발현되는 지 확인하고자 하였다. 정상 청력을 지닌 20대 성인 33명이 실험에 참여하였다. 자극음으로 두 개의 한국어 단음절 /자/와 /차/, 4개의 주파수로 구성된 톤버스트음(500, 1000, 2000, 4000 Hz)을 사용하여 청성뇌간반응을 얻었다. 연구 결과, 단음절과 톤버스트음 모두 높은 재현성을 보였고, 파형 V는 모든 피검자에게서 잘 발현되었다. 피어슨 상관관계 분석 결과, 3671 ~ 5384 Hz 대역에서 에너지 분포를 갖는 /자/ 음절은 4000 Hz의 톤버스트음과 높은 상관관계를 나타냈다. 그러나 /차/ 음절은 1000 Hz와 2000 Hz의 톤버스트음과 높은 상관성을 보여, 3362~5412 Hz의 음향적 특성과 청각 뇌간에서 생리학적 반응은 일치하지 않았다. 이러한 결과를 바탕으로 사람의 어음인지과정을 면밀히 조사하기 위해 음향-청지각적 매핑후속 연구가 필요하겠다. It is widely acknowledged that the human auditory system is organized tonotopically and people generally listen to sounds as a function of frequency distribution through the auditory system. However, it is still unclear how acoustic features of speech sounds are indicated to the human brain in terms of speech perception. Thus, the purpose of this study is to investigate whether two sounds with similar high-frequency characteristics in the acoustic analysis show similar results at the level of auditory brainstem. Thirty three young adults with normal hearing participated in the study. As stimuli, two Korean monosyllables (i.e., /ja/ and /cha/) and four frequencies of toneburst (i.e., 500, 1000, 2000, and 4000 Hz) were used to elicit the auditory brainstem response (ABR). Measures of monosyllable and toneburst were highly replicable and the wave V of waveform was detectable in all subjects. In the results of Pearson correlation analysis, the /ja/ syllable had a high correlation with 4000 Hz of toneburst which means that its acoustic characteristics (i.e., 3671~5384 Hz) showed the same results in the brainstem. However, the /cha/ syllable had a high correlation with 1000 and 2000 Hz of toneburst although it has acoustical distribution of 3362~5412 Hz. We concluded that there was disagreement between acoustic features and physiology outcomes at the auditory brainstem level. This finding suggests that an acoustical-perceptual mapping study is needed to scrutinize human speech perception.

Context-dependent categorical perception in a songbird

The division of continuously variable acoustic signals into discrete perceptual categories is a fundamental feature of human speech. Other animals have been found to categorize speech sounds much the same as humans do, although little is known of the role of categorical perception by animals in their own natural communication systems. A hallmark of human categorical perception of speech is that linguistic context affects both how speech sounds are categorized into phonemes, and how different versions of phonemes are produced. I first review earlier findings showing that a species of songbird, the swamp sparrow, categorically perceives the notes that constitute its learned songs and that individual neurons in the bird’s brain show categorical responses that map onto its behavioral response. I then present more recent data, using both discrimination and labeling tests, that show how swamp sparrows perceive categorical boundaries differently depending on context. These results demonstrate that there is a more complex relationship between underlying categorical representations and surface forms in the perception of birdsong. To our knowledge, this work suggests for the first time that this higher-order characteristic of human phonology is also found in a nonhuman communication system.

Environmental enrichment rescues the degraded auditory temporal resolution of cortical neurons induced by early noise exposure.

The accurate processing of sound temporal information is crucial to human speech perception and other species-specific communication. During postnatal development, the auditory cortex shows environmental and experience-dependent plasticity. However, how the postnatal environment affects cortical processing of sound temporal information is not fully understood. The aim of the present study was to determine whether postnatal noise exposure impairs neural temporal resolution in the auditory cortex, and, if so, whether environmental enrichment can rescue this degraded neural temporal acuity. Using the neural gap detection threshold determined in anesthetized rats as an index of temporal acuity, we found that exposure of juvenile rats to moderate-level noise induced much higher neural gap detection thresholds in adulthood than exposure of adult rats to the same noise. Environmental enrichment did not affect cortical neural gap detection thresholds in normally developing rats. However, rearing of rats with early noise exposure in an enriched environment promoted recovery from the noise-induced degraded neural temporal resolution. In addition, the tonal stimuli in the enriched environment contributed to only a portion of the recovery. These results provide evidence for noise-induced developmental impairment in neural gap detection thresholds in the auditory cortex, and suggest a therapeutic potential for environmental enrichment as a non-invasive approach to rescue developmentally degraded auditory temporal processing.

Multi-time resolution analysis of speech: evidence from psychophysics.

How speech signals are analyzed and represented remains a foundational challenge both for cognitive science and neuroscience. A growing body of research, employing various behavioral and neurobiological experimental techniques, now points to the perceptual relevance of both phoneme-sized (10–40 Hz modulation frequency) and syllable-sized (2–10 Hz modulation frequency) units in speech processing. However, it is not clear how information associated with such different time scales interacts in a manner relevant for speech perception. We report behavioral experiments on speech intelligibility employing a stimulus that allows us to investigate how distinct temporal modulations in speech are treated separately and whether they are combined. We created sentences in which the slow (~4 Hz; Slow) and rapid (~33 Hz; Shigh) modulations—corresponding to ~250 and ~30 ms, the average duration of syllables and certain phonetic properties, respectively—were selectively extracted. Although Slow and Shigh have low intelligibility when presented separately, dichotic presentation of Shigh with Slow results in supra-additive performance, suggesting a synergistic relationship between low- and high-modulation frequencies. A second experiment desynchronized presentation of the Slow and Shigh signals. Desynchronizing signals relative to one another had no impact on intelligibility when delays were less than ~45 ms. Longer delays resulted in a steep intelligibility decline, providing further evidence of integration or binding of information within restricted temporal windows. Our data suggest that human speech perception uses multi-time resolution processing. Signals are concurrently analyzed on at least two separate time scales, the intermediate representations of these analyses are integrated, and the resulting bound percept has significant consequences for speech intelligibility—a view compatible with recent insights from neuroscience implicating multi-timescale auditory processing.

ViSQOL: an objective speech quality model

This paper presents an objective speech quality model, ViSQOL, the Virtual Speech Quality Objective Listener. It is a signal-based, full-reference, intrusive metric that models human speech quality perception using a spectro-temporal measure of similarity between a reference and a test speech signal. The metric has been particularly designed to be robust for quality issues associated with Voice over IP (VoIP) transmission. This paper describes the algorithm and compares the quality predictions with the ITU-T standard metrics PESQ and POLQA for common problems in VoIP: clock drift, associated time warping, and playout delays. The results indicate that ViSQOL and POLQA significantly outperform PESQ, with ViSQOL competing well with POLQA. An extensive benchmarking against PESQ, POLQA, and simpler distance metrics using three speech corpora (NOIZEUS and E4 and the ITU-T P.Sup. 23 database) is also presented. These experiments benchmark the performance for a wide range of quality impairments, including VoIP degradations, a variety of background noise types, speech enhancement methods, and SNR levels. The results and subsequent analysis show that both ViSQOL and POLQA have some performance weaknesses and under-predict perceived quality in certain VoIP conditions. Both have a wider application and robustness to conditions than PESQ or more trivial distance metrics. ViSQOL is shown to offer a useful alternative to POLQA in predicting speech quality in VoIP scenarios.

The effects of hearing loss on neural processing and plasticity.

The effects of hearing loss on neural processing and plasticity.

Perceptual learning in the developing auditory cortex.

A hallmark of the developing auditory cortex is the heightened plasticity in the critical period, during which acoustic inputs can indelibly alter cortical function. However, not all sounds in the natural acoustic environment are ethologically relevant. How does the auditory system resolve relevant sounds from the acoustic environment in such an early developmental stage when most associative learning mechanisms are not yet fully functional? What can the auditory system learn from one of the most important classes of sounds, animal vocalizations? How does naturalistic acoustic experience shape cortical sound representation and perception? To answer these questions, we need to consider an unusual strategy, statistical learning, where what the system needs to learn is embedded in the sensory input. Here, I will review recent findings on how certain statistical structures of natural animal vocalizations shape auditory cortical acoustic representations, and how cortical plasticity may underlie learned categorical sound perception. These results will be discussed in the context of human speech perception.

A longitudinal assessment of vocabulary retention in symbol-competent chimpanzees (Pan troglodytes).

A number of studies from the 1960s to 1990s assessed the symbolic competence of great apes and other animals. These studies provided varying forms of evidence that some species were capable of symbolically representing their worlds, both through productive symbol use and comprehension of symbolic stimuli. One such project at the Language Research Center involved training chimpanzees (Pan troglodytes) to use lexigram symbols (geometric visual stimuli that represented objects, actions, locations, and individuals). Those studies now are more than 40 years old, and only a few of the apes involved in those studies are still alive. Three of these chimpanzees (and a fourth, control chimpanzee) were assessed across a 10-year period from 1999 to 2008 for their continued knowledge of lexigram symbols and, in the case of one chimpanzee, the continued ability to comprehend human speech. This article describes that longitudinal assessment and outlines the degree to which symbol competence was retained by these chimpanzees across that decade-long period. All chimpanzees showed retention of lexigram vocabularies, although there were differences in the number of words that were retained across the individuals. One chimpanzee also showed continual retention of human speech perception. These retained vocabularies largely consisted of food item names, but also names of inedible objects, locations, individuals, and some actions. Many of these retained words were for things that are not common in the daily lives of the chimpanzees and for things that are rarely requested by the chimpanzees. Thus, the early experiences of these chimpanzees in symbol-rich environments have produced long-lasting memories for symbol meaning, and those competencies have benefited research in a variety of topics in comparative cognition.

Hindi phoneme classification using Wiener filtered wavelet packet decomposed periodic and aperiodic acoustic feature

Wavelet packet (WP) acoustic features are found to be very promising in unvoiced phoneme classification task but they are less effective to capture periodic information from voiced speech. This motivated us to develop a wavelet packet based feature extraction technique that signifies both the periodic and aperiodic information. This method is based on parallel distributed processing technique inspired by the human speech perception process. This front end feature processing technique employs Equivalent Rectangular Bandwidth (ERB) filter like wavelet speech feature extraction method called Wavelet ERB Sub-band based Periodicity and Aperiodicity Decomposition (WERB-SPADE). Winer filter is used at front end to minimize the noise for further processing. The speech signal is filtered by 24 band ERB like wavelet filter banks, and then the output of each sub-band is processed through comb filter. Each comb filter is designed individually for each sub-band to decompose the signal into periodic and aperiodic features. Thus it carries the periodic information without losing certain important information like formant transition incorporated in aperiodic features. Hindi phoneme classification experiments with a standard HMM recognizer under both clean-training and multi-training condition is conducted. This technique shows significant improvement in voiced phoneme class without affecting the performance of unvoiced phoneme class.

Revisiting vocal perception in non-human animals: a review of vowel discrimination, speaker voice recognition, and speaker normalization.

The extent to which human speech perception evolved by taking advantage of predispositions and pre-existing features of vertebrate auditory and cognitive systems remains a central question in the evolution of speech. This paper reviews asymmetries in vowel perception, speaker voice recognition, and speaker normalization in non-human animals – topics that have not been thoroughly discussed in relation to the abilities of non-human animals, but are nonetheless important aspects of vocal perception. Throughout this paper we demonstrate that addressing these issues in non-human animals is relevant and worthwhile because many non-human animals must deal with similar issues in their natural environment. That is, they must also discriminate between similar-sounding vocalizations, determine signaler identity from vocalizations, and resolve signaler-dependent variation in vocalizations from conspecifics. Overall, we find that, although plausible, the current evidence is insufficiently strong to conclude that directional asymmetries in vowel perception are specific to humans, or that non-human animals can use voice characteristics to recognize human individuals. However, we do find some indication that non-human animals can normalize speaker differences. Accordingly, we identify avenues for future research that would greatly improve and advance our understanding of these topics.

To Mu is to Move, to Tau is to Understand: a Possible Functional Role for Lower Alpha Oscillations in Human Speech Perception.

Event Abstract Back to Event To Mu is to Move, to Tau is to Understand: a Possible Functional Role for Lower Alpha Oscillations in Human Speech Perception. Bernadine Cocks1, 2*, Graham Jamieson2 and Ian Evans2 1 University of South Australia, ITE&E, Australia 2 University of New England, BCSS, Australia Contemporary research suggests that the alpha band (8-12Hz) of the human EEG signal can be divided into functionally discrete sub-bands. Within the alpha range, at least two additional functional rhythms are proposed; tau (6.5-9.5Hz) and mu (7.5-12.5Hz). These sub-bands are primarily distinguished based on oscillatory activity at specific cortical sites; thus mu is associated with activity in motor/sensorimotor areas and tau with activity in auditory areas; thus event-related synchronisation/desynchronisation (ERS/ERD) to auditory stimuli in the lower alpha range by sources within the temporal lobes would be classified as a tau rhythm. Although tau has previously been associated with lower order sound processing, any involvement in higher order processing is unknown. To explore this further, the current study collected continuous 64 channel EEG from 27 participants as they undertook two tasks: (i) passive listening to a variety of animal noises; and (ii) a grammatical decision task involving both real and nonsense English word stimuli. Following FFT, significantly higher ERD was observed in the lower alpha, or tau range for human words and primate vocalisations when compared to other animal vocalisation types. This difference was independent of acoustic differences. The ERD data was then analysed via eLoreta with desynchronization localised to both primary and secondary auditory processing areas suggesting that tau responds to both lower and higher order processing. Given that this response was common to both human speech and primate vocalisations, with primate vocalisations and nonsense words evoking the greatest ERD, this suggests that tau may also be suppressed when identifying whether a complex sound is meaningful, that is speech related, and deserving of further language processing. Keywords: Speech Perception, EEG, tau, ERS/ERD, complex sound processing Conference: XII International Conference on Cognitive Neuroscience (ICON-XII), Brisbane, Queensland, Australia, 27 Jul - 31 Jul, 2014. Presentation Type: Poster Topic: Sensation and Perception Citation: Cocks B, Jamieson G and Evans I (2015). To Mu is to Move, to Tau is to Understand: a Possible Functional Role for Lower Alpha Oscillations in Human Speech Perception.. Conference Abstract: XII International Conference on Cognitive Neuroscience (ICON-XII). doi: 10.3389/conf.fnhum.2015.217.00133 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 19 Feb 2015; Published Online: 24 Apr 2015. * Correspondence: Ms. Bernadine Cocks, University of South Australia, ITE&E, Adelaide, Australia, Bernie.Cocks@unisa.edu.au Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Bernadine Cocks Graham Jamieson Ian Evans Google Bernadine Cocks Graham Jamieson Ian Evans Google Scholar Bernadine Cocks Graham Jamieson Ian Evans PubMed Bernadine Cocks Graham Jamieson Ian Evans Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.