Revisiting the effect of text complexity on Continuous Discourse Tracking using synthetic speech: Old tricks with new dogs.

Continuous Discourse Tracking (CDT) is a functional test of speech perceptual ability, which has been criticised on account of the procedural variation inherent in the method. This study sought to reduce this variation by using synthetic speech, which was subsequently vocoded to simulate listening with a cochlear implant. We also assessed the complexity of three text excerpts with auditory (n = 10) and written Cloze tests (n = 10). These same passages were used in an auditory-only CDT experiment (n = 12) performed with the synthetic-vocoded material. Mean tracking rates were lower, and the number of blockages was higher for the most difficult text as determined by the Cloze results. We also noted some anomalous realisations from the speech synthesis, but these were unlikely to have contributed to the differences in tracking rates that were observed for text complexity. These results show that Cloze testing is suitable to predict text complexity for CDT performed with synthesised speech. Furthermore, they indicate that the use of text-speech synthesis is viable and may be a useful addition to rehabilitation where functional measures are used to assess communication aptitude.

The long and the short of vowel length perception in Danish.

Danish is a quantity language in which the length of vowels is either short or long. This study investigates vowel length in order to determine the degree to which we can ascribe the conventional categorical tag to vowel quantity perception. In a pilot study (n = 18) the gradual shortening of long vowels was identified as methodologically preferable for deriving stimuli continua, as complete identification functions could be fitted to the mean data. We employed this method to derive stimuli for identification and discrimination experiments (n = 32) that included the words used in the pilot and another word pair. This pair has phonetically similar variation in vowel duration although, due to recent language change, quantity is no longer contrastive. Results from the phonologically contrastive word pairs showed sigmoidal identification functions and discrimination peaks in the middle of the continua, while the identification slope for the non-contrastive pair was approximately linear and there was no clear discrimination peak. These differences show that the perception of speech contrasts is influenced by the linguistic experience of listeners as well as auditory and articulatory factors.

Lateralized Readiness Potentials Recorded with Near-Threshold Auditory Stimuli in Subjects Simulating Hearing Loss.

INTRODUCTION: Preparatory motor cortical responses like the lateralized readiness potential (LRP) may be useful in revealing persistent attempts to feign hearing loss. Previous studies suggest only a marginal effect of stimulus intensity on the amplitude of the LRP. However, this has not been investigated using low-intensity auditory stimuli to cue NoGo trials. We address this in an experiment where subjects were instructed not to give a manual response to low-instensity stimuli, a situation that is akin to simulating hearing loss. METHODS: The LRP was recorded from normal hearing listeners (N = 10) with 500 and 4,000-Hz pure tones and trains of 4,000 Hz (2-1-2) tonebursts. Electrophysiologic data underwent processing to (i) analyze the effect of the stimulus type on the LRP, (ii) classify results according to manual response with both logistic regression and linear support vector machine (SVM) models, and (iii) derive auditory brainstem responses (ABRs) from the tonebursts. RESULTS: The amplitude of the LRP did not differ between the 3 stimuli used to elicit the response. Single-trial electrode data from Go and NoGo trials were submitted to supervised binary classification, and the logistic regression model gave a mean accuracy of close to 0.7. The Jewett wave V latencies of the resultant ABRs from some subjects were found to increase between the high (Go) and low (NoGo) intensity tonebursts. CONCLUSION: This study shows that auditory stimulus type does not affect the amplitude of the LRP and that the response can be recorded with stimuli that are near the auditory threshold. It can also be recorded with transient stimuli, and this allows for the possibility of simultaneously recording other confirmatory measurements, like ABR.

Genomic reconstruction of the SARS-CoV-2 epidemic across England from September 2020 to May 2021

The evolution of the SARS-CoV-2 pandemic continuously produces new variants, which warrant timely epidemiological characterisation. Here we use the dense genomic surveillance generated by the COVID-19 Genomics UK Consortium to reconstruct the dynamics of 71 different lineages in each of 315 English local authorities between September 2020 and June 2021. This analysis reveals a series of sub-epidemics that peaked in the early autumn of 2020, followed by a jump in transmissibility of the B.1.1.7/Alpha lineage. Alpha grew when other lineages declined during the second national lockdown and regionally tiered restrictions between November and December 2020. A third more stringent national lockdown suppressed Alpha and eliminated nearly all other lineages in early 2021. However, a series of variants (mostly containing the spike E484K mutation) defied these trends and persisted at moderately increasing proportions. Accounting for sustained introductions, however, indicates that their transmissibility is unlikely to have exceeded that of Alpha. Finally, B.1.617.2/Delta was repeatedly introduced to England and grew rapidly in the early summer of 2021, constituting approximately 98% of sampled SARS-CoV-2 genomes on June 26.

Rapid expression of COVID-19 proteins by transient expression in tobacco.

In 2020 we suffered from a major global pandemic caused by the SARS-CoV-2 coronavirus. Efforts to contain the virus include the development of rapid tests and vaccines, which require a ready supply of viral proteins. Here we report the production of two SARS-CoV-2 proteins by transient transformation of tobacco, leading to high expression within three days, and subsequent purification of the intact proteins. Such efforts may help to develop testing resources to alleviate the major impacts of this global pandemic.

COVID-19 infection dynamics in care homes in the East of England: a retrospective genomic epidemiology study

COVID-19 poses a major challenge to care homes, as SARS-CoV-2 is readily transmitted and causes disproportionately severe disease in older people. Here, 1,167 residents from 337 care homes were identified from a dataset of 6,600 COVID-19 cases from the East of England. Older age and being a care home resident were associated with increased mortality. SARS-CoV-2 genomes were available for 700 residents from 292 care homes. By integrating genomic and temporal data, 409 viral clusters within the 292 homes were identified, indicating two different patterns - outbreaks among care home residents and independent introductions with limited onward transmission. Approximately 70% of residents in the genomic analysis were admitted to hospital during the study, providing extensive opportunities for transmission between care homes and hospitals. Limiting viral transmission within care homes should be a key target for infection control to reduce COVID-19 mortality in this population. Impact statementSARS-CoV-2 can spread efficiently within care homes causing COVID-19 outbreaks among residents, who are at increased risk of severe disease, emphasising the importance of stringent infection control in this population.

Can the Lateralized Readiness Potential Detect Suppressed Manual Responses to Pure Tones?

BACKGROUND: Willfully not responding to auditory stimuli hampers accurate behavioral measurements. An objective measure of covert manual suppression recorded during response tasks may be useful to assess the veracity of responses to stimuli. PURPOSE: To investigate whether the lateralized readiness potential (LRP), an electrophysiological measure of corticomotor response and suppression, may be of use in determining when participants hear but do not respond to pure tones. RESEARCH DESIGN: Within-subject repeated measures with a Go-NoGo paradigm. STUDY SAMPLE: Five males and five females (mean age = 38.8 years, standard deviation = 8.8) underwent electrophysiology testing. All had normal hearing, except one. INTERVENTION: Participants were tested in a condition where they consistently responded to tonal stimuli, and in a condition where intensity cued whether they should respond or not. Scalp-recorded cortical potentials and behavioral responses were recorded, along with a question that probed the perceived effort required to suppress responses to the stimuli. DATA COLLECTION AND ANALYSIS: Electrophysiology data were processed with independent component analysis and epoch-based artifact rejection. Averaged group and individual LRPs were calculated. RESULTS: Group averaged waveforms show that suppressed responses, cued by NoGo stimuli, diverge positively at approximately 300 msec poststimulus, when compared with performed (Go) responses. LRPs were comparable when Go responses were recorded in a separate condition in which participants responded to all stimuli, and when Go and NoGo trials were included in the same condition. The LRP was not observed in one participant. CONCLUSIONS: Subsequent to further investigation, the LRP may prove suitable in assessing the suppression of responses to audiometric stimuli, and, thereby, useful in cases where functional hearing loss is suspected.

Standardization of the Prosody in Use Battery (PUB): a speech prosody perception test in Danish.

Assessment of prosody perception may be useful in a number of clinical scenarios, including the rehabilitation of cochlear implant recipients. It is with this group in mind that we have derived and standardized a battery of tests that assess speech prosody perception in the Danish language. The prosodic contrasts included in the battery are vowel length, compounds and phrases, emotions, questions and statements, prominence and pronoun reference, all of which are commonly encountered in everyday communication. Lists of candidate stimuli were compiled and recorded by a representative speaker of Danish. All candidate stimuli were presented to normal hearing subjects (n = 12) in both unprocessed and 8-channel noise vocoded conditions. Subjects performed closed-set identification and the results were used to derive the final stimulus set. We report the results of the six subtests, in which we observed a bias to compounds in the compound/phrase subtest, and to statements in question/statement subtest. The pronoun reference subtest assessed the ability of a listener to infer a referent from the stress status of a pronoun, and we found high accuracy rates on this task indicating that it is suitable for inclusion in the battery. We discuss the possible uses of the Prosody in Use Battery in cochlear implant mapping and device verification. We also consider the role of the results from the test battery in guiding clinicians to material suitable for aural rehabilitation.

Electrophysiological and behavioral measures of some speech contrasts in varied attention and noise.

This paper investigates the salience of speech contrasts in noise, in relation to how listening attention affects scalp-recorded cortical responses. The contrasts that were examined with consonant-vowel syllables, were place of articulation, vowel length and voice-onset time (VOT) and our analysis focuses on the correspondence between the effect of attention on the electrophysiology and the decrement in behavioral results when noise was added to the stimuli. Normal-hearing subjects (n = 20) performed closed-set syllable identification in no noise, 0, 4 and 8 dB signal-noise ratio (SNR). Identification in noise decreased markedly for place of articulation, moderately for vowel length and marginally for VOT. The same syllables were used in two electrophysiology conditions, where subjects attended to the stimuli, and also while their attention was diverted to a visual discrimination task. Differences in global field power between the attention conditions from each contrast showed that that the effect of attention was negligible for place of articulation. They implied offset encoding of vowel length and were early (starting at 117 ms), and of high amplitude (>3 µV) for VOT. There were significant correlations between the difference in syllable identification in no noise and 0 dB SNR and the electrophysiology results between attention conditions for the VOT contrast. Comparison of the two attention conditions with microstate analysis showed a significant difference in the duration of microstate class D. These results show differential integration of attention and syllable processing according to speech contrast and they suggest that there is correspondence between the salience of a contrast in noise and the effect of attention on the evoked electrical response.

The Military ACL.

Anterior cruciate ligament (ACL) injuries in the U.S. Military Service members have a 10-fold higher incidence than that of the general population due to the physically demanding aspects of military duties. Although some controversy exists on the specific techniques or reconstruction, these injuries are uniformly reconstructed due to the requirements of their occupation and the effect of these injuries on their future careers. As such, understanding the care of the military Service member's ACL may help optimize the care of the physically active injured knee.

Investigating lexical competition and the cost of phonemic restoration.

Due to phonemic restoration, listeners can reliably perceive words when a phoneme is replaced with noise. The cost associated with this process was investigated along with the effect of lexical uniqueness on phonemic restoration, using data from a lexical decision experiment where noise replaced phonemes that were either uniqueness points (the phoneme at which a word deviates from all nonrelated words that share the same onset) or phonemes immediately prior to these. A baseline condition was also included with no noise-interrupted stimuli. Results showed a significant cost of phonemic restoration, with 100 ms longer word identification times and a 14% decrease in word identification accuracy for interrupted stimuli compared to the baseline. Regression analysis of response times from the interrupted conditions showed no effect of whether the interrupted phoneme was a uniqueness point, but significant effects for several temporal attributes of the stimuli, including the duration and position of the interrupted segment. These results indicate that uniqueness points are not distinct breakpoints in the cohort reduction that occurs during lexical processing, but that temporal properties of the interrupted stimuli are central to auditory word recognition. These results are interpreted in the context of models of speech perception.

Cognitive Load in Voice Therapy Carry-Over Exercises.

Purpose: The cognitive load generated by online speech production may vary with the nature of the speech task. This article examines 3 speech tasks used in voice therapy carry-over exercises, in which a patient is required to adopt and automatize new voice behaviors, ultimately in daily spontaneous communication. Method: Twelve subjects produced speech in 3 conditions: rote speech (weekdays), sentences in a set form, and semispontaneous speech. Subjects simultaneously performed a secondary visual discrimination task for which response times were measured. On completion of each speech task, subjects rated their experience on a questionnaire. Results: Response times from the secondary, visual task were found to be shortest for the rote speech, longer for the semispontaneous speech, and longest for the sentences within the set framework. Principal components derived from the subjective ratings were found to be linked to response times on the secondary visual task. Acoustic measures reflecting fundamental frequency distribution and vocal fold compression varied across the speech tasks. Conclusions: The results indicate that consideration should be given to the selection of speech tasks during the process leading to automation of revised speech behavior and that self-reports may be a reliable index of cognitive load.

Isolation of high quality lignin as a by-product from ammonia percolation pretreatment of poplar wood.

A two-step process combining percolation-mode ammonia pretreatment of poplar sawdust with mild organosolv purification of the extracted lignin produced high quality, high purity lignin in up to 31% yield and 50% recovery. The uncondensed fraction of the isolated lignin was up to 34%, close to that the native lignin (40%). Less lignin was recovered after pretreatment in batch mode, apparently due to condensation during the longer residence time of the solubilised lignin at elevated temperature. The lignin recovery was directly correlated with its molecular weight and its nitrogen content. Low nitrogen incorporation, observed at high ammonia concentration, may be explained by limited homolytic cleavage of ß-O-4 bonds. Ammonia concentrations from 15% to 25% (w/w) gave similar results in terms of lignin structure, yield and recovery.

Organosolv pretreatment of Sitka spruce wood: conversion of hemicelluloses to ethyl glycosides.

A range of Organosolv pretreatments, using ethanol:water mixtures with dilute sulphuric acid, were applied to Sitka spruce sawdust with the aim of generating useful co-products as well as improving saccharification yield. The most efficient of the pretreatment conditions, resulting in subsequent saccharification yields of up to 86%, converted a large part of the hemicellulose sugars to their ethyl glycosides as identified by GC/MS. These conditions also reduced conversion of pentoses to furfural, the ethyl glycosides being more stable to dehydration than the parent pentoses. Through comparison with the behaviour of model compounds under the same reaction conditions it was shown that the anomeric composition of the products was consistent with a predominant transglycosylation reaction mechanism, rather than hydrolysis followed by glycosylation. The ethyl glycosides have potential as intermediates in the sustainable production of high-value chemicals.