RESUMO
ABSTRACT The difficulties of applying the audiometry in pediatric populations and its methodological limitations in implanted patients have spurred the development of new alternative auditory evaluation methods. This study aimed to show an objective method to estimate hearing thresholds in pediatric cochlear implanted patients through Electrical Cochlear Response (ECR) and to quantify the hearing performance by using an Auditory Skills Questionnaire (ASQ) and a Calibrated Sounds Test (CST) designed on purpose. Eighteen implanted patients, 1-6 years old underwent standard audiometry, ECR, and ASQ in two evaluation sessions T1 and T2. At T2, in addition, patients underwent CST. For patients ≤3 years old (G1), Pure Tone Averages (PTA and PTAECR)showed a statistically significant difference between them at T1 and T2. At T2 improvements in audiometric and ECR thresholds were observed (p<0.05), regarding T1. Patients older than 3 years (G2) had significantly better ASQ and CST scores. CST detection scores at 40 dBHL for groups G1 and G2, 36% and 70% respectively, showed a better relationship to ECR thresholds. The relationship observed between ECR thresholds and CST detection scores seems to confirm that ECR brings the feasibility of objective hearing threshold estimation and provides a better frequency resolution than audiometry.
RESUMEN Las dificultades para la aplicación de la audiometría en la población pediátrica además de sus limitaciones metodológicas en pacientes usuarios de implante coclear, señalan la necesidad de métodos audiométricos alternos. En el presente trabajo se utiliza el potencial eléctrico, denominado Respuesta Coclear Eléctrica (ECR) observado solamente en usuarios de implante coclear, para la estimación de umbrales auditivos prescindiendo de la participación consiente del paciente, además de evaluar el desempeño auditivo mediante un Cuestionario de Habilidades Auditivas (ASQ) y la Prueba de Sonidos Calibrados (CST). A dieciocho participantes de 1 a 6 años, se les practicó Audiometría, ECR y ASQ en dos sesiones, T1 y T2; adicionalmente, en T2 se aplicó CST. En T1 y T2 los promedios de tonos puros, PTA y PTAECR, de pacientes ≤ 3 años (G1), mostraron una diferencia estadísticamente significativa entre ellos. En T2 los umbrales audiométricos y ECR (p <0.05), mejoraron respecto de T1. Pacientes > 3 años (G2) lograron puntuaciones ASQ y CST significativamente mejores. Los puntajes de detección CST a 40 dBHL, G1(36%) y G2(70%), mostraron mejor relación con los umbrales ECR. Esta relación entre los umbrales ECR y los puntajes de detección CST indican que la ECR permite estimar el umbral de audición, logrando adicionalmente mayor resolución en frecuencia que la audiometría.
RESUMO
A critical part of applying Independent Component Analysis (ICA) to any neurophysiological data is the selection of relevant independent Components (ICs); i. e., to decide which ICs have neurological meaning. Standard ICA implementation supposes a square mixing matrix; this results in as many ICs as EEG channels. In this work, responses to repetitive auditory stimuli are the most important signals (Auditory Evoked Potentials, AEPs); so the ICs of interest should be repetitive and time-locked with the stimuli. In this paper an update of a previously proposed procedure for the objective selection of ICs using Mutual Information (MI) and cluster analysis is presented. This time, four different similarity functions are evaluated and three inter/intra-cluster quality criteria are explored to determine optimal cluster numbers to both synthetic AEPs and data from normal hearing children, so that to identify ICs related with the auditory response. The numbers of clusters and the similarity function that yield best results in both datasets, in other words optimal clustering AEPs ICs, were 8 and Euclidean link-clustering average respectively.
