Recommendations of good practice to prevent aspiration pneumonia in older adults at risk of oropharyngeal dysphagia living in nursing homes: A modified e-Delphi study protocol.

BACKGROUND: Aspiration pneumonia (AP) is a subset of pneumonia caused by the aspiration of food and fluids to the lungs and is highly prevalent in the older population. Oropharyngeal dysphagia (OD) is one of the risk factors for AP and it is also associated with malnutrition, dehydration and poor functional outcomes. As pneumonia is the second most common infection in nursing homes (NHs) and OD represents a major concern to NH staff, good practices for the prevention of AP in older adults at risk of OD are needed. PURPOSE: The aim of this modified e-Delphi study is to build consensus among a panel of experts regarding a set of recommendations for NH staff on good practices to prevent AP in older adults at risk of OD living in NHs. The objective of this paper is to establish the methodology inherent to the Delphi study. METHODS: An online modified Delphi study will be developed in three rounds. Criteria for the Delphi panel participants include holding a master's or doctoral degree in OD or speech and language therapy; or having 10 or more years of experience in OD; or having at least one scientific publication related to OD. A previously described modified Delphi methodology will be used to achieve consensus (75% agreement). An additional round will be performed to collect the experts' perspectives regarding the priority for application of each recommendation previously validated. DISCUSSION: This protocol aimed to describe the methodology of a future Delphi study on the prevention of AP, seeking to fulfil the gap in the literature regarding this topic. The modified Delphi technique is a widely used method for collecting experts' opinion in health sciences, but the absence of standardised guidelines allows some heterogeneity between studies with the same aim. WHAT THIS PAPER ADDS: What is already known on the subject Aspiration pneumonia (AP) is related to three main risk factors: impaired safety of swallow, impaired nutritional status and poor oral health. It is known that being dependent for feeding is one of the main risk factors for AP and around 50% of nursing home (NH) residents need feeding assistance. Thus, it is important to promote specialised intervention and care by the NH staff for preventing AP. What this paper adds to existing knowledge It is hypothesised that increasing the knowledge of NH staff regarding the best practices for preventing AP in older adults at risk of oropharyngeal dysphagia (OD) will improve outcomes such as quality of life, incidence of AP and mortality. What are the potential or actual clinical implications of this work? The recommendations resulting from this study will address a current gap in healthcare practice of NH staff regarding older adults at increased risk for OD and, consequently, for AP.

Identification of words in whispered speech: The role of cues to fricatives' place and voicing.

The temporal distribution of acoustic cues in whispered speech was analyzed using the gating paradigm. Fifteen Portuguese participants listened to real disyllabic words produced by four Portuguese speakers. Lexical choices, confidence scores, isolation points (IPs), and recognition points (RPs) were analyzed. Mixed effects models predicted that the first syllable and 70% of the total duration of the second syllable were needed for lexical choices to be above chance level. Fricatives' place, not voicing, had a significant effect on the percentage of correctly identified words. IP and RP values of words with postalveolar voiced and voiceless fricatives were significantly different.

Oral and Laryngeal Articulation Control of Voicing in Children with and without Speech Sound Disorders.

Voicing contrast is hard to master during speech motor development, and the phonological process of consonant devoicing is very frequent in children with Speech Sound Disorders (SSD). Therefore, the aim of this study was to characterise the oral and laryngeal articulation control strategies used by children with and without SSD as a function of place of articulation. The articulation rate and relative oral airflow amplitude (flow) were used to analyse how children controlled oral articulation; fundamental frequency (fo), open quotient (OQ), and a classification of voicing were used to explore laryngeal behaviour. Data from detailed speech and language assessments, oral airflow and electroglottography signals were collected from 13 children with SSD and 17 children without SSD, aged 5; 0 to 7; 8, using picture naming tasks. Articulation rate and flow in children with and without SSD were not significantly different, but a statistically reliable effect of place on flow was found. Children with and without SSD used different relative fo (which captures changes in fo during the consonant-vowel transition) and OQ values, and place of articulation had an effect on the strength of voicing. All children used very similar oral articulation control of voicing, but children with SSD used less efficient laryngeal articulation strategies (higher subglottal damping and more air from the lungs expelled in each glottal cycle) than children without SSD.

An Open Access Standardised Voice Evaluation Protocol.

PURPOSE: A comprehensive protocol to evaluate voice quality can support a full characterisation of voice disorders and be used to plan voice interventions. The purpose of this study was to develop and validate a standardised protocol for voice assessment, contributing with a comprehensive and valuable tool for clinician practice and research. METHOD: The initial structure and content of the protocol was based on an extensive literature review of existing voice assessment tools. The content validity was then assessed by a panel of voice specialist, using a modified Bland and Altman graphical method and the intraclass correlation coefficient (ICC). A group of participants with vocal pathology was finally assessed by two voice specialists on the same day (inter-rater reliability), and, on a second day, by a single evaluator (intra-rater reliability). Inter and intra-reliability were evaluated through Cohen's kappa (k) for nominal variables, and Spearman's Correlation Coefficient (ρ) for quantitative and ordinal variables. RESULTS: The Bland and Altman analysis, revealed a reasonable agreement between the experts and the ICC values were lower than expected, but the confidence intervals were very wide. The intra-rater reliability of the protocol's nominal variables was almost perfect, with a mean k of 0.977; inter-rater reliability of nominal variables was also almost perfect, with a mean k of 0.893. The ordinal and quantitative variables revealed a very good to excellent relationship, with a mean ρ of 0.912. CONCLUSIONS: Evidence of content validity, high intra and inter-rater reliability of a standardised protocol for voice assessment, have been shown. This protocol can be used to assess and collect data from patients, to train voice specialists and to develop reference voice databases. It has been designed to serve voice experts with diverse backgrounds and assessment needs.

Language assessment in awake brain surgery: the Portuguese adaptation of the Dutch linguistic intraoperative protocol (DuLIP).

Awake brain surgery, combined with neurophysiological evaluation and intraoperative mapping, is one of the preferential lines of treatment when approaching low-grade gliomas. Speech and language assessment is used while applying Direct Electrical Stimulation (DES) and during the resection of a lesion/tumour, as it allows to establish related eloquent areas and optimise the extent of the resection and avoid impairments. Patients need to be assessed pre, intra and post-surgery, but in under resourced countries such as Portugal, there are still no standardised and validated tools to conduct this type of evaluation. To address this need, the tasks of the Dutch Linguistic Intraoperative Protocol (DuLIP) were adapted to European Portuguese, and the resulting materials were standardised for a group of 144 Portuguese participants. For each task, the impact of age, gender and schooling were measured. The resulting Portuguese version of the DuLIP (DuLIP-EP) consists of 17 tasks, including phonological, syntactic, semantic, naming and articulatory tests. No significant differences were found between male and female participants. However, schooling influenced phonological and syntactic fluency, object naming and verb generation. Schooling and age had a significant impact on semantic fluency and reading with semantic odd word out tasks. This is the first contribution to the standardisation of a tool that can be used during an awake brain surgery in Portugal, which includes a new phonological odd word out task that is not currently available in the Dutch version.

Interventions to Prevent Aspiration Pneumonia in Older Adults: An Updated Systematic Review.

Purpose The aim of the study was to provide an updated systematic review of randomized controlled trials that studied the effectiveness of pharmacological and nonpharmacological interventions to prevent aspiration pneumonia in older adults at risk for aspiration. Method The search was conducted in MEDLINE (PubMed), Scopus, and Web of Science databases and the Cochrane Central Register of Controlled Trials, using a protocol registered on PROSPERO (CRD42019139973). Randomized controlled trials of interventions to reduce the incidence of aspiration pneumonia in individuals older than 65 years at risk for aspiration, published between January 2002 and July 2019 and written in English, were included. Two reviewers independently evaluated the methodological quality of studies using the revised Cochrane risk-of-bias tool. Results Thirteen out of 703 articles identified met the eligibility criteria and were included. Six studies focused on pharmacological interventions, three studies focused on dietary interventions and compensatory strategies, one study focused on oral care, two studies focused on multidisciplinary interventions, and one study assessed a screening method. Four studies showed positive and statistically significant effect in reducing aspiration pneumonia but were considered to have unclear or high risk of bias. Three studies showed promising results on the preventive effect of pharmacological interventions. Conclusions The most recent evidence on the prevention of aspiration pneumonia in older adults revealed modest to poor methodological quality. Given the burden of aspiration pneumonia on patients and on the health care systems, the development of larger well-designed trials on this topic is of undoubted importance.

RELEASE: a protocol for a systematic review based, individual participant data, meta- and network meta-analysis, of complex speech-language therapy interventions for stroke-related aphasia.

Background: Speech and language therapy (SLT) benefits people with aphasia following stroke. Group level summary statistics from randomised controlled trials hinder exploration of highly complex SLT interventions and a clinically relevant heterogeneous population. Creating a database of individual participant data (IPD) for people with aphasia aims to allow exploration of individual and therapy-related predictors of recovery and prognosis. Aim: To explore the contribution that individual participant characteristics (including stroke and aphasia profiles) and SLT intervention components make to language recovery following stroke. Methods and procedures: We will identify eligible IPD datasets (including randomised controlled trials, non-randomised comparison studies, observational studies and registries) and invite their contribution to the database. Where possible, we will use meta- and network meta-analysis to explore language performance after stroke and predictors of recovery as it relates to participants who had no SLT, historical SLT or SLT in the primary research study. We will also examine the components of effective SLT interventions. Outcomes and results: Outcomes include changes in measures of functional communication, overall severity of language impairment, auditory comprehension, spoken language (including naming), reading and writing from baseline. Data captured on assessment tools will be collated and transformed to a standardised measure for each of the outcome domains. Conclusion: Our planned systematic-review-based IPD meta- and network meta-analysis is a large scale, international, multidisciplinary and methodologically complex endeavour. It will enable hypotheses to be generated and tested to optimise and inform development of interventions for people with aphasia after stroke. Systematic review registration: The protocol has been registered at the International Prospective Register of Systematic Reviews (PROSPERO; registration number: CRD42018110947).

Treating Children With Speech Sound Disorders: Development of a Tangible Artefact Prototype.

BACKGROUND: A prototype of a tangible user interface (TUI) for a fishing game, which is intended to be used by children with speech sound disorders (SSD), speech and language therapists (SLTs), and kindergarten teachers and assistants (KTAs) and parents alike, has been developed and tested. OBJECTIVE: The aim of this study was to answer the following question: How can TUIs be used as a tool to help in interventions for children with SSD? METHODS: To obtain feedback and to ensure that the prototype was being developed according to the needs of the identified target users, an exploratory test was prepared and carried out. During this test using an ethnographic approach, an observation grid, a semistructured questionnaire, and interviews were used to gather data. A total of 4 different types of stakeholders (sample size of 10) tested the prototype: 2 SLTs, 2 KTAs, and 6 children. RESULTS: The analysis of quantitative and qualitative data revealed that the prototype addresses the existing needs of SLTs and KTAs, and it revealed that 5 out of 6 (83%) children enjoyed the activity. Results also revealed a high replay value, with all children saying they would play more. CONCLUSIONS: Serious games and tangible interaction for learning and problem solving serve both teachers and children, as children enjoy playing, and, through a playful approach, learning is facilitated. A clear pattern was observed: Children enjoyed playing, and numerous valid indicators showed the transposition of the traditional game into the TUI artefact was successful. The game is varied and rich enough to be attractive and fun. There is a clear need and interest in similar objects from SLTs and educators. However, the process should be even more iterative, with a multidisciplinary team, and all end users should be able to participate as co-designers.

Comparing Traditional and Tablet-Based Intervention for Children With Speech Sound Disorders: A Randomized Controlled Trial.

Purpose This article reports on the effectiveness of a novel tablet-based approach to phonological intervention and compares it to a traditional tabletop approach, targeting children with phonologically based speech sound disorders (SSD). Method Twenty-two Portuguese children with phonologically based SSD were randomly assigned to 1 of 2 interventions, tabletop or tablet (11 children in each group), and received intervention based on the same activities, with the only difference being the delivery. All children were treated by the same speech-language pathologist over 2 blocks of 6 weekly sessions, for 12 sessions of intervention. Participants were assessed at 3 time points: baseline; pre-intervention, after a 3-month waiting period; and post-intervention. Outcome measures included percentage of consonants correct, percentage of vowels correct, and percentage of phonemes correct. A generalization of target sounds was also explored. Results Both tabletop and tablet-based interventions were effective in improving percentage of consonants correct and percentage of phonemes correct scores, with an intervention effect only evident for percentage of vowels correct in the tablet group. Change scores across both interventions were significantly greater after the intervention, compared to baseline, indicating that the change was due to the intervention. High levels of generalization (60% and above for the majority of participants) were obtained across both tabletop and tablet groups. Conclusions The software proved to be as effective as a traditional tabletop approach in treating children with phonologically based SSD. These findings provide new evidence regarding the use of digital materials in improving speech in children with SSD. Supplemental Material https://doi.org/10.23641/asha.9989816.

/l/ velarisation as a continuum.

In this paper, we present a production study to explore the controversial question about /l/ velarisation. Measurements of first (F1), second (F2) and third (F3) formant frequencies and the slope of F2 were analysed to clarify the /l/ velarisation behaviour in European Portuguese (EP). The acoustic data were collected from ten EP speakers, producing trisyllabic words with paroxytone stress pattern, with the liquid consonant at the middle of the word in onset, complex onset and coda positions. Results suggested that /l/ is produced on a continuum in EP. The consistently low F2 indicates that /l/ is velarised in all syllable positions, but variation especially in F1 and F3 revealed that /l/ could be "more velarised" or "less velarised" dependent on syllable positions and vowel contexts. These findings suggest that it is important to consider different acoustic measures to better understand /l/ velarisation in EP.

Reliability and validity evidence of the Assessment of Language Use in Social Contexts for Adults (ALUSCA).

Background: The appropriate use of language in context depends on the speaker's pragmatic language competencies. A coding system was used to develop a specific and adult-focused self-administered questionnaire to adults who stutter and adults who do not stutter, The Assessment of Language Use in Social Contexts for Adults, with three categories: precursors, basic exchanges, and extended literal/non-literal discourse. This paper presents the content validity, item analysis, reliability coefficients and evidences of construct validity of the instrument. Methods: Content validity analysis was based on a two-stage process: first, 11 pragmatic questionnaires were assessed to identify items that probe each pragmatic competency and to create the first version of the instrument; second, items were assessed qualitatively by an expert panel composed by adults who stutter and controls, and quantitatively and qualitatively by an expert panel composed by clinicians. A pilot study was conducted with five adults who stutter and five controls to analyse items and calculate reliability. Construct validity evidences were obtained using the hypothesized relationships method and factor analysis with 28 adults who stutter and 28 controls. Results: Concerning content validity, the questionnaires assessed up to 13 pragmatic competencies. Qualitative and quantitative analysis revealed ambiguities in items construction. Disagreement between experts was solved through item modification. The pilot study showed that the instrument presented internal consistency and temporal stability. Significant differences between adults who stutter and controls and different response profiles revealed the instrument's underlying construct. Conclusion: The instrument is reliable and presented evidences of construct validity.

Visual stimuli in intervention approaches for pre-schoolers diagnosed with phonological delay.

The aim of this study was to develop and content validate specific speech and language intervention picture cards: The Letter-Sound (L&S) cards. The present study was also focused on assessing the influence of these cards on letter-sound correspondences and speech sound production. An expert panel of six speech and language therapists analysed and discussed the L&S cards based on several criteria previously established. A Speech and Language Therapist carried out a 6-week therapeutic intervention with a group of seven Portuguese phonologically delayed pre-schoolers aged 5;3 to 6;5. The modified Bland-Altman method revealed good agreement among evaluators, that is the majority of the values was between the agreement limits. Additional outcome measures were collected before and after the therapeutic intervention process. Results indicate that the L&S cards facilitate the acquisition of letter-sound correspondences. Regarding speech sound production, some improvements were also observed at word level. The L&S cards are therefore likely to give phonetic cues, which are crucial for the correct production of therapeutic targets. These visual cues seemed to have helped children with phonological delay develop the above-mentioned skills.

Usability of Computerized Lung Auscultation-Sound Software (CLASS) for learning pulmonary auscultation.

The mastering of pulmonary auscultation requires complex acoustic skills. Computer-assisted learning tools (CALTs) have potential to enhance the learning of these skills; however, few have been developed for this purpose and do not integrate all the required features. Thus, this study aimed to assess the usability of a new CALT for learning pulmonary auscultation. Computerized Lung Auscultation-Sound Software (CLASS) usability was assessed by eight physiotherapy students using computer screen recordings, think-aloud reports, and facial expressions. Time spent in each task, frequency of messages and facial expressions, number of clicks and problems reported were counted. The timelines of the three methods used were matched/synchronized and analyzed. The tasks exercises and annotation of respiratory sounds were the ones requiring more clicks (median 132, interquartile range [23-157]; 93 [53-155]; 91 [65-104], respectively) and where most errors (19; 37; 15%, respectively) and problems (n = 7; 6; 3, respectively) were reported. Each participant reported a median of 6 problems, with a total of 14 different problems found, mainly related with CLASS functionalities (50%). Smile was the only facial expression presented in all tasks (n = 54). CLASS is the only CALT available that meets all the required features for learning pulmonary auscultation. The combination of the three usability methods identified advantages/disadvantages of CLASS and offered guidance for future developments, namely in annotations and exercises. This will allow the improvement of CLASS and enhance students' activities for learning pulmonary auscultation skills.

The letter knowledge assessment tool.

PURPOSE: There is a need to develop letter knowledge assessment tools to characterise the letter knowledge in Portuguese pre-schoolers and to compare it with pre-schoolers from other countries, but there are no tools for this purpose in Portugal. The aim of this paper is to describe the development and validation procedures of the Prova de Avaliação de Competências de Pré-Literacia (PACPL), which assesses letter knowledge. METHOD: This study includes data that has been gathered in two phases: pilot and main study. In the pilot study, an expert panel of six speech and language pathologists analysed the instrument. Children (n = 216) aged 5;0-7;11 participated in the main study that reports data related to the psychometric characteristics of the PACPL. Content validity, internal consistency, reliability and contributing factors to performance were examined statistically. RESULTS: A modified Bland-Altman method revealed good agreement amongst evaluators. The main study showed that the PACPL has a very good internal consistency and high inter-rater (96.2% of agreement and a Cohen's k value of 0.92) and intra-rater (95.6% of agreement and a Cohen's k value of 0.91) agreement. Construct validity of the PCAPL was also assured (Cronbach's α of 0.982). Significant differences were found between age groups with children increasing their letter knowledge with age. In addition, they were better at identifying than at producing both letter names and letter sounds. CONCLUSIONS: The PACPL is a valid and reliable instrument to assess letter knowledge in Portuguese children.

A country-wide probability sample of public attitudes toward stuttering in Portugal.

BACKGROUND: Negative public attitudes toward stuttering have been widely reported, although differences among countries and regions exist. Clear reasons for these differences remain obscure. PURPOSE: Published research is unavailable on public attitudes toward stuttering in Portugal as well as a representative sample that explores stuttering attitudes in an entire country. This study sought to (a) determine the feasibility of a country-wide probability sampling scheme to measure public stuttering attitudes in Portugal using a standard instrument (the Public Opinion Survey of Human Attributes-Stuttering [POSHA-S]) and (b) identify demographic variables that predict Portuguese attitudes. METHODS: The POSHA-S was translated to European Portuguese through a five-step process. Thereafter, a local administrative office-based, three-stage, cluster, probability sampling scheme was carried out to obtain 311 adult respondents who filled out the questionnaire. RESULTS: The Portuguese population held stuttering attitudes that were generally within the average range of those observed from numerous previous POSHA-S samples. Demographic variables that predicted more versus less positive stuttering attitudes were respondents' age, region of the country, years of school completed, working situation, and number of languages spoken. Non-predicting variables were respondents' sex, marital status, and parental status. CONCLUSION: A local administrative office-based, probability sampling scheme generated a respondent profile similar to census data and indicated that Portuguese attitudes are generally typical.

Paediatric Automatic Phonological Analysis Tools (APAT).

PURPOSE: To develop the pediatric Automatic Phonological Analysis Tools (APAT) and to estimate inter and intrajudge reliability, content validity, and concurrent validity. METHOD: The APAT were constructed using Excel spreadsheets with formulas. The tools were presented to an expert panel for content validation. The corpus used in the Portuguese standardized test Teste Fonético-Fonológico - ALPE produced by 24 children with phonological delay or phonological disorder was recorded, transcribed, and then inserted into the APAT. Reliability and validity of APAT were analyzed. RESULTS: The APAT present strong inter- and intrajudge reliability (>97%). The content validity was also analyzed (ICC = 0.71), and concurrent validity revealed strong correlations between computerized and manual (traditional) methods. CONCLUSIONS: The development of these tools contributes to fill existing gaps in clinical practice and research, since previously there were no valid and reliable tools/instruments for automatic phonological analysis, which allowed the analysis of different corpora.

Stop and Fricative Devoicing in European Portuguese, Italian and German.

This paper describes a cross-linguistic production study of devoicing for European Portuguese (EP), Italian, and German. We recorded all stops and fricatives in four vowel contexts and two word positions. We computed the devoicing of the time-varying patterns throughout the stop and fricative duration. Our results show that regarding devoicing behaviour, EP is more similar to German than Italian. While Italian shows almost no devoicing of all phonologically voiced consonants, both EP and German show strong and consistent devoicing through the entire consonant. Differences in consonant position showed no effect for EP and Italian, but were significantly different for German. The height of the vowel context had an effect for German and EP. For EP, we showed that a more posterior place of articulation and low vowel context lead to significantly more devoicing. However, in contrast to German, we could not find an influence of consonant position on devoicing. The high devoicing for all phonologically voiced stops and fricatives and the vowel context influence are a surprising new result. With respect to voicing maintenance, EP is more like German than other Romance languages.

Acoustic Correlates of Compensatory Adjustments to the Glottic and Supraglottic Structures in Patients with Unilateral Vocal Fold Paralysis.

The goal of this study was to analyse perceptually and acoustically the voices of patients with Unilateral Vocal Fold Paralysis (UVFP) and compare them to the voices of normal subjects. These voices were analysed perceptually with the GRBAS scale and acoustically using the following parameters: mean fundamental frequency (F0), standard-deviation of F0, jitter (ppq5), shimmer (apq11), mean harmonics-to-noise ratio (HNR), mean first (F1) and second (F2) formants frequency, and standard-deviation of F1 and F2 frequencies. Statistically significant differences were found in all of the perceptual parameters. Also the jitter, shimmer, HNR, standard-deviation of F0, and standard-deviation of the frequency of F2 were statistically different between groups, for both genders. In the male data differences were also found in F1 and F2 frequencies values and in the standard-deviation of the frequency of F1. This study allowed the documentation of the alterations resulting from UVFP and addressed the exploration of parameters with limited information for this pathology.

Event- and interval-based measurement of stuttering: a review.

BACKGROUND: Event- and interval-based measurements are two different ways of computing frequency of stuttering. Interval-based methodology emerged as an alternative measure to overcome problems associated with reproducibility in the event-based methodology. No review has been made to study the effect of methodological factors in interval-based absolute reliability data or to compute the agreement between the two methodologies in terms of inter-judge, intra-judge and accuracy (i.e., correspondence between raters' scores and an established criterion). AIMS: To provide a review related to reproducibility of event-based and time-interval measurement, and to verify the effect of methodological factors (training, experience, interval duration, sample presentation order and judgment conditions) on agreement of time-interval measurement; in addition, to determine if it is possible to quantify the agreement between the two methodologies METHODS & PROCEDURES: The first two authors searched for articles on ERIC, MEDLINE, PubMed, B-on, CENTRAL and Dissertation Abstracts during January-February 2013 and retrieved 495 articles. Forty-eight articles were selected for review. Content tables were constructed with the main findings. MAIN CONTRIBUTION: Articles related to event-based measurements revealed values of inter- and intra-judge greater than 0.70 and agreement percentages beyond 80%. The articles related to time-interval measures revealed that, in general, judges with more experience with stuttering presented significantly higher levels of intra- and inter-judge agreement. Inter- and intra-judge values were beyond the references for high reproducibility values for both methodologies. Accuracy (regarding the closeness of raters' judgements with an established criterion), intra- and inter-judge agreement were higher for trained groups when compared with non-trained groups. Sample presentation order and audio/video conditions did not result in differences in inter- or intra-judge results. A duration of 5 s for an interval appears to be an acceptable agreement. Explanation for high reproducibility values as well as parameter choice to report those data are discussed. CONCLUSIONS & IMPLICATIONS: Both interval- and event-based methodologies used trained or experienced judges for inter- and intra-judge determination and data were beyond the references for good reproducibility values. Inter- and intra-judge values were reported in different metric scales among event- and interval-based methods studies, making it unfeasible to quantify the agreement between the two methods.

Cue-weighting in the perception of intervocalic stop voicing in European Portuguese.

This paper describes the perception of intervocalic stop voicing in European Portuguese (EP) stimuli without a stop burst, when varying three acoustic cues: Vowel duration, stop duration, and voicing maintenance during stop closure. Perceptual stimuli were generated using biomechanical modeling. First, a discrimination experiment was conducted to determine the listeners' perceptual sensitivity to the voicing maintenance cue. Second, an identification experiment was conducted to examine the effect and interaction of vowel duration, stop duration, and voicing maintenance during stop closure on the voiced/voiceless identification responses of EP listeners. The results of the discrimination test show that voicing maintenance differences have a significant effect as soon as they exceed a certain threshold. In the identification experiment, evidence was found that only the two factors vowel duration and voicing maintenance significantly influence the listeners' decisions, but not stop duration. The ratio between stop duration and vowel duration plays a major role in distinguishing stop voicing, but only for highly devoiced stimuli. It is shown that in stimuli without a stop burst, both voicing maintenance, as a major but not required cue, and vowel duration are important acoustic cues for stop voicing distinctions in EP.