Importance of Perimodiolar Electrode Position for Psychoacoustic Discrimination in Cochlear Implantation.

HYPOTHESIS: Modiolar proximity of the cochlear implant electrodes and low impedance values have a positive effect on electrical pitch discrimination. BACKGROUND: The proximity of the cochlear electrode to the modiolar wall can determine changes in tissue and fluid environment. With the onset of soft-surgery techniques, the trauma caused during surgery has been reduced, minimizing fibrous growth. METHODS: Computed tomography-scan measurements of electrode-inner wall distance and psychoacoustic electrode discrimination tests were done. Neural Response Telemery and impedance data were used in the study. RESULTS: It was found that patients fitted with perimodiolar arrays have lower impedance values and smaller electrode-inner wall distances than those fitted with straight arrays. These variables were significantly correlated to electrode discrimination. It was found that a closer distance to the modiolus also results in better electrode discrimination. CONCLUSION: Perimodiolar electrodes could be a better solution in terms of pitch discrimination both because they are closer to the modiolus and because their impedance is lower.

Effects of Long-Term Speech-in-Noise Training in Air Traffic Controllers and High Frequency Suppression. A Control Group Study.

OBJECTIVE: To evaluate 1) if air traffic controllers (ATC) perform better than non-air traffic controllers in an open-set speech-in-noise test because of their experience with radio communications, and 2) if high-frequency information (>8000 Hz) substantially improves speech-in-noise perception across populations. MATERIALS AND METHODS: The control group comprised 28 normal-hearing subjects, and the target group comprised 48 ATCs aged between 19 and 55 years who were native Spanish speakers. The hearing -in-noise abilities of the two groups were characterized under two signal conditions: 1) speech tokens and white noise sampled at 44.1 kHz (unfiltered condition) and 2) speech tokens plus white noise, each passed through a 4th order Butterworth filter with 70 and 8000 Hz low and high cutoffs (filtered condition). These tests were performed at signal-to-noise ratios of +5, 0, and -5-dB SNR. RESULTS: The ATCs outperformed the control group in all conditions. The differences were statistically significant in all cases, and the largest difference was observed under the most difficult conditions (-5 dB SNR). Overall, scores were higher when high-frequency components were not suppressed for both groups, although statistically significant differences were not observed for the control group at 0 dB SNR. CONCLUSION: The results indicate that ATCs are more capable of identifying speech in noise. This may be due to the effect of their training. On the other hand, performance seems to decrease when the high frequency components of speech are removed, regardless of training.

The Effect of Reference Electrode Position in Cochlear Implants.

OBJECTIVE: This study aims to evaluate the increase in power of cochlear implants (CI) as the reference electrode (RE) position changes. Patients in whom it is necessary to use the full power of the device to achieve the desired stimulation levels, this strategy will ensure that stimulation capability is maximized. MATERIALS AND METHODS: The variability in RE placement in the temporal bone has a measurable effect on the electrical current, impedance, and power consumption, and if the electrode position has a functional effect on the stimulation intensity. The following three approaches were used: 1) classical circuit analysis, 2) 2-dimensional numerical simulations, and 3) real temporal bone measurements using a purpose-made CI. RESULTS: The three approaches demonstrate a significant decrease in the current intensity and electrical resistance for distances that are closer to the intra-cochlear electrode. The results also demonstrate that to maintain a constant current, shorter distances require 33% less power. CONCLUSION: Reference electrode position during surgery can make significant differences in CI power consumption and threshold intensity, which allows a more powerful stimulation in complicated patients (i.e., those with otosclerosis). This study presents an attractive perspective to surgeons, as it shows a way to decrease consumption that might result in a longer battery life or more power to be devoted to coding strategy performance.

Effects of high-frequency suppression for speech recognition in noise in Spanish normal-hearing subjects.

HYPOTHESIS: Subjects with normal hearing (NH) experience lower performance in speech understanding in noise when frequency components of speech above 8 kHz are removed. BACKGROUND: Previous studies have explored speech perception in noise under various circumstances, but none have been specifically designed to explore the relevance of frequencies above 8 kHz and, more specifically, for the Spanish language. METHODS: Twenty-nine subjects with NH, aged 19 to 55 years, and native speakers of the Spanish language listened to two sets of three disyllabic word lists with background noise. One set of words was unfiltered and included frequency components up to 22 kHz, and another set was band-pass filtered to include frequency components between 70 Hz and 8 kHz. Words were presented at 65 dB sound pressure level. Each set of words was presented with background noise with the same bandwidth limit as the accompanying list and adjusted to construct signal-to-noise ratio (SNR) conditions of +5, 0, and -5 dB. RESULTS: Results demonstrate a higher performance for unfiltered words at +5 and -5 dB SNR, although not at 0 dB SNR. For SNR +5 dB and -5 dB, the average success rate in word recognition was 17% higher when words were not filtered. For the case SNR = 0, however, both conditions yield statistically similar results. CONCLUSION: This study suggests that high-frequency components above 8 kHz contribute to speech understanding in noise for subjects with NH of the Spanish language. Given these findings, it would be interesting to determine if bandwidth limitations in current hearing prostheses may contribute to known difficulties with perception of speech in noise in hearing-impaired subjects.

Morfología interna del primer molar mandibular permanente. Influencia del uso de ultrasonidos y del microscopio operatorio en la localización de conductos / Internal morphology of the mandibular first permanent molar. Influence of the use of ultrasonic tips and operating microscope in locating canals

Introducción: Estudios recientes reflejan la existencia de conductos accesorios en las raíces de los primeros molares permanentes inferiores. El objetivo principal de este trabajo es determinar la influencia que tienen el uso de ultrasonidos y el microscopio operatorio en la localización de dichos conductos. Como objetivo secundario, hemos empleado la técnica de diafanización de manera innovadora para visualizar la anatomía real de los molares inferiores tratados. Metodología: Se realizó la apertura de 53primeros molares permanentes inferiores en varias fases, anotando el número de conductos localizados en cada una de ellas. La primera, sin magnificación ni ultrasonidos. A continuación se incorporaron la puntas ultrasónicas y, en una tercera fase, se añadió el microscopio operatorio. Finalmente se utilizó la técnica descrita por Robertson para diafanizar los dientes y describir sus sistemas de conductos mediante la clasificación de Vertucci, modificada por diversos autores. Resultados: Tanto el uso de ultrasonidos como del microscopio operatorio, aumentaron el número de conductos localizados, pero las diferencias sólo fueron estadísticamente significativas con el uso simultáneo de ambos. Su ayuda fue más importante en la raíz mesial que en la distal. Un 26.4% de las raíces mesiales presentaba tres orificios de entrada a la cámara pulpar, cuyas configuraciones hacia la zona apical son (..) (AU)

Introduction: Recent studies reflect the existence of accessory canals in the roots of the first lower permanent molars. The main objective of this paper is to determine the influence that the use of ultrasonic tips and the operating microscope have in locating these canals. As a secondary objective, we have used the clearing technique in an innovative way to visualize the actual anatomy ofthe treated lower molars. Methodology: The access cavities of 53 first lower permanent molars were done indifferent phases, noting the number of canals located in each of them. The first, without magnification or ultrasound. Next the ultrasonic tips were incorporated and, in a third phase, the operating microscope was added. Finally, the technique described by Robertson was used to make the teeth transparent and describe their root canal systems by means of the Vertucci’s classification, modified by various authors. Results: Both the use of ultrasound and the operating microscope increased the number of located canals, but the differences were only statistically significant with the (..) (AU)