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The goal of this study was to investigate the phonetic realisation of the voicing feature in two tumour resection-related Spanish speakers with apraxia of speech. Temporal parameters related to the phonological contrast of voicing in Spanish have been analysed for intervocalic voiced and voiceless obstruents embedded in isolated words and nonwords, and compared with data collected from healthy speakers. Results indicate that in devoiced productions, where VOT values fitted the 'voiceless stops' category, vowel duration values matched those of voiced stops and suggested the preservation of contextual voicing cues. An attempt at preserving a consonant/vowel duration ratio consistent with aerodynamic predictions for voicing contrast has been observed in apraxic correct production as well as in devoicing errors, but not in the control group, which could be interpreted as a compensatory mechanism.

Citation / Cómo citar este artículo: Anna Marczyk and Lorraine Baqué. Predicting segmental substitution errors in aphasic patients with phonological and phonetic encoding impairments. Loquens, 2(2), e023. doi: http://dx.doi. org/10. 3989/loquens.2015.023 ABSTRACT: This paper analyses the factors that predict substitution errors produced by four Broca's and four conduction aphasic subjects, all native speakers of Spanish, in reading and repetition tasks. Errors were elicited using a list of words where type of consonant, lexical stress and phonetic context were controlled for and where variables related to frequency of occurrence (word and syllable) and phonological neighbourhood characteristics were assigned using available online corpora. 675 substitution errors were obtained and preferential tendencies to devoice, occlusivise or spirantise were identified. Logistic regression mixed-effect models were performed on these three types of substitution errors to identify the predictors depending on the aphasic profile.While our results lent support to the hypothesis of a concomitant phonetic deficit in fluent aphasia, contrary to the classical claim, it also revealed differential patterns in the phonic behaviour of patients regarding the access to mental syllabary or syllabic position effects.Our results are discussed in relation to the phonetic vs. phonological impairments dimension in aphasia and the seriality/interactivity axis in speech architectures.Keywords: phonetic and phonological impairments; aphasia; substitution errors. RESUMEN: Estudio de predictores de los errores segmentales de sustitución en pacientes afásicos con un déficit fonético-fonológico.Este estudio se propone identificar los factores que permiten predecir la aparición de errores segmentales de sustitución producidos por pacientes con afasia de Broca y de conducción en tareas de lectura y de repetición. El corpus utilizado para obtener los errores consistía en 240 palabras en las que las consonantes objeto de estudio -oclusivas, fricativas y africadas del español-se encontraban en distintos contextos fonéticos y acentuales. Posteriormente, se atribuyó a las palabras del corpus los valores relativos a la frecuencia léxica y silábica, así como las características relacionadas con la vecindad fonológica, empleando para ello corpus disponibles en línea.En total, se obtuvieron 675 sustituciones, en las que prevalecen tres tendencias: ensordecimiento de las oclusivas sonoras, refuerzo (oclusivización) de las fricativas y espirantización de las oclusivas. Para identificar los predictores de cualquiera de estos tres tipos de substitución en relación con el perfil clínico de afasia, se efectuó un análisis mediante el modelo mixto de regresión logística.Los resultados son globalmente congruentes con la hipótesis de un déficit fonético concomitante al déficit fonológico en la afasia de conducción, contrariamente a las predicciones de la hipótesis clásica. Sin embargo, el examen de los errores revela también patrones de tratamiento fónico distintos se...

This article reports on vowel clarity metrics based on spectrotemporal modulations of speech signals. Motivated by previous findings on the relevance of modulation-based metrics for speech intelligibility assessment and pathology classification, the current study used factor analysis to identify regions within a bi-dimensional modulation space, the magnitude power spectrum, as in Elliott and Theunissen [(2009). PLoS Comput. Biol. 5(3), e1000302] by relating them to a set of conventional acoustic metrics of vowel space area and vowel distinctiveness. Two indices based on the energy ratio between high and low modulation rates across temporal and spectral dimensions of the modulation space emerged from the analyses. These indices served as input for measurements of central tendency and classification analyses that aimed to identify vowel-related speech impairments in French native speakers with head and neck cancer (HNC) and Parkinson dysarthria (PD). Following the analysis, vowel-related speech impairment was identified in HNC speakers, but not in PD. These results were consistent with findings based on subjective evaluations of speech intelligibility. The findings reported are consistent with previous studies indicating that impaired speech is associated with attenuation in energy in higher spectrotemporal modulation bands.