ABSTRACT
Introducción: La estimación de la audición con Potenciales Evocados Auditivos de Tallo Cerebral obtenidos mediante estímulos tipo chirp constituye una alternativa de reciente aplicación. Varios autores han demostrado que, este tipo de estimulación compensa el retardo de la onda sonora en la codificación de frecuencias, generándose Potenciales Evocados Auditivos de Tallo Cerebral con componentes de amplitudes mayores. Objetivos: Diseñar y generar un estímulo chirp (banda ancha) para implementar en el sistema AUDIX (La Habana, Neuronic SA) y, realizar una serie de controles para evaluar su viabilidad en el registro de Potenciales Evocados Auditivos de Tallo Cerebral en sujetos con audición normal. Métodos: Las formulaciones que se utilizaron en la generación del estímulo fueron implementadas como una función en Matlab®, y luego, insertada en el sistema AUDIX con las siguientes especificaciones técnicas, frecuencia de muestreo: 48 kHz, composición de frecuencias (ascendente): 350-11300 Hz, y duración total: 4,95 ms. Se obtuvieron registros de PEATC mediante estímulos chirp y click a un nivel de intensidad fija (60 dB nHL) en 9 sujetos adultos (18 oídos) con audición normal. Resultados: El estímulo chirp diseñado tuvo un comportamiento funcional similar a lo reportado en la literatura. Cuando se compara con los Potenciales Evocados Auditivos de Tallo Cerebral -click, la onda V de Potenciales Evocados Auditivos de Tallo Cerebral -chirp mostró valores de amplitud significativamente mayores (relación de amplitud chirp/click: 1,62), con una ganancia promedio de 54 por ciento (p< 0,001, n= 18, prueba de rangos de Wilcoxon). Conclusiones: El estímulo chirp (banda ancha) diseñado resulta más eficiente que el estímulo click para obtener registros de Potenciales Evocados Auditivos de Tallo Cerebral. Con respecto a la amplitud de la onda V, el sistema muestra un funcionamiento lineal (mejor sincronía neural). Este tipo de estimulación pudiera resultar de mucha utilidad en programas de pesquisa auditiva neonatal pues la obtención de una onda V de mayor amplitud permitiría su fácil y rápida detección, y posible automatización(AU)
Introduction: Estimation of audition through brainstem auditory evoked potentials obtained by chirp stimuli is an alternative of recent application. It has been shown by several authors that this type of stimulation compensates for retardation of the sound wave in the coding of frequencies, generating auditory evoked responses with components of higher amplitudes. Objectives: Design and develop a broad-band chirp stimulus to be implemented in the AUDIX system and conduct a control series evaluation of its viability to register brainstem auditory evoked potentials in normal-hearing subjects. Methods: The formulations used to generate the stimulus were implemented as a function on Matlab® and then incorporated into the AUDIX system with the following technical specifications: sampling frequency: 48 kHz, frequency composition (rising): 350-11 300 Hz, and total duration: 4.95 ms. BAEP registries were obtained with chirp and click stimuli at a fixed intensity level (60 dB nHL) in nine normal-hearing adult subjects (18 ears). Results: The chirp stimulus designed had a functional behavior similar to the one reported in the literature. When compared with the click-BAEP, the V wave of chirp-BAEP displayed significantly higher amplitude values (chirp/click amplitude ratio: 1.62), with an average gain of 54 percent (p< 0.001, n= 18, Wilcoxon rank test). Conclusions: The broad band chirp stimulus designed proved to be more efficient than the click stimulus to obtain registries of Brainstem Auditory Evoked Potentials. Regarding V wave amplitude, the system was found to function linearly (better neural synchrony). This type of stimulation could be very useful in neonatal hearing screening programs, since a higher amplitude V wave could facilitate its fast and easy detection and possible automation(AU)
ABSTRACT
By combining frequency modulation Chirp Z transform ion mobility spectrometers (IMS) and multi nozzle electrospray array ionization source, a method of NanoESI-Chirp Z transform ion mobility spectrometry-high performance liquid chromatography was developed for the determination of n-alkyl ammonium bromide compounds.The parameters of NanoESI-Chirp Z transform IMS such as electric field intensity, solvent composition, and solution flow rate were investigated and optimized.Subsequently, four kinds of n-alkyl ammonium bromide compounds were respectively detected by this developed Chirp Z transform method and Fourier transform method, and the obtained results were compared.The result indicated that the optimum conditions were electric field intensity of 4.5 kV, and ESI solution flow rate of 8 μL/min.Then a test mixture containing tetrabutylammonium bromide, tetrapentylammoniumbromide, tetrahexylammonium bromide, tetraheptylammonium bromide, tetranoctylammoniumbromideandtetrakis(decyl) ammonium bromide was successfully separated and determined by the HPLC-nanoESI-Chirp Z IMS method.Chirp Z transform method provided higher signal to noise ratio compared to conventional signal averaging method, and was superior to FT method in the determination of drift time.
ABSTRACT
Objective To study the clinical significance of Chirp-ASSR and the characteristics of hearing loss patients by ASSR(auditory steady-state responses) under Chirp stimulation.Methods A total of 136 hearing loss children (5～10 years old) with 272 ears were distributed into four groups based on 500 Hz,1 000 Hz,2 000 Hz and 4 000 Hz auditory threshold arithmetic average:20～dB HL,40～dB HL,60～dB HL,and≥80 dB HL groups.To compare the correlation of the PTA and Chirp-ASSR in different frequencies domain through SPSS statistics 19.0 software,the data were used T-test and Pearson analysis.Results ①The group(≥80 dB HL) achieved a statistically significant higher reaction threshold than pure tone threshold.②The correlation index γ'of PTA and Chirp-ASSR showed a decline along with the hearing loss increase;It increased along with the test frequency,there was a significant difference between 500 Hz and 4 000 Hz(P＜0.05).Conclusion Chirp-ASSR is a frequency-specific electrophysiological test method,it could reflect the truthful listening ability,especially in mild,moderate,and severe hearing loss children.
ABSTRACT
Introducción: El potencial evocado auditivo de tronco cerebral (PEATC) se ha convertido en un procedimiento estándar dentro de la evaluación audiológica. Durante décadas, el estímulo más utilizado ha sido el clic, sin embargo, últimamente se ha propuesto la utilización de estímulos de frecuencia modulada (chirp) para obtener resultados más eficientes. Objetivo: Comparar las amplitudes y las latencias de la onda V del PEATC obtenidas a través de estímulos clic y CE-Chirp® a distintas intensidades. Material y método: Se realizó un estudio de tipo cuantitativo, no experimental, transversal y descriptivo en 17 sujetos a los que se evaluó con un PEATC utilizando estímulos clic y CE-Chirp®. Resultados: Se obtuvieron mayores amplitudes de onda Vpara estímulos CE-Chirp® que para clic, en todas las intensidades evaluadas (80, 60, 40,30 y 20 dBnHL). Se obtuvieron menores latencias en la onda Vpara estímulos CE-Chirp® solo a 80 y 60 dBnHL, mientras que en el resto de las intensidades se obtuvo menores latencias con estímulos clic. Conclusiones: Existen diferencias significativas entre las latencias y amplitudes de la onda V obtenidas con estímulos clic y CE-Chirp®. Mientras los estímulos CE-Chirp® aportan en rapidez en el examen y en la búsqueda del umbral electrofisiológico más preciso, los estímulos clic serían los adecuados al momento de realizar un estudio de topodiagnóstico.
Introduction: The auditory brainstem response (ABR) has become a standard procedure in the audiological evaluation. For decades the most widely used stimulus was the click, but recently the use of chirp stimulus has been proposed for obtain more efficient results. Aim: To compare the amplitudes and latencies of wave V of ABR obtained through click and CE-Chirp® stimuli at different intensities. Material and method: A quantitative, not experimental, transversal and descriptive study was conducted with 17 subjects who were evaluated with ABR using click and CE-Chirp® stimuli. Results: Wave V larger amplitudes were verified for stimulus CE-Chirp®, in all the evaluated intensities (80, 60, 40, 30 and 20 dBnHL). Shorter latencies of wave V were obtained for CE-Chirp® stimuli only at 80 and 60 dBnHL, while it was found that the remaining intensities showed lower latencies with click stimuli. Conclusions: There are significant differences between latencies and amplitudes of the wave V obtained with CE-Chirp® and click stimuli. While the CE-Chirp® stimuli provides faster results for most accurate electrophysiological threshold, click stimuli would be appropriate to conduct site of the lesion testing.
Subject(s)
Humans , Male , Female , Adult , Young Adult , Acoustic Stimulation/methods , Evoked Potentials, Auditory, Brain Stem/physiology , Hearing/physiology , Auditory Threshold , Cross-Sectional Studies , Reaction TimeABSTRACT
Objective To analyze the characteristic of auditory brainstem responses (ABR) evoked by chirp in normal hearing subjects .Methods Fifteen cases (30 ears) with normal hearing young people were recorded ABR by stimulation with two kinds of sounds :chirp and click .The data were compared .Results The response threshold of chirp-ABR were lower than that of click -ABR .The average difference was 8 .59 dB .At 90 dB nHL ,the wave V amplitude yield no significant difference between chirp -ABR and click-ABR .The wave V amplitude had a signifi-cant difference between chirp -ABR and click-ABR at 60 dB nHL .At 90 and 60 dB nHL ,the wave V amplitude of chirp-ABR had not a significant difference .The occurence rate was 40% for the wave I of chirp -ABR ,obvi-ously less than that of click -ABR .At 90 dB nHL ,the wave V latency of chirp -ABR was shorter than that of click-ABR .Conclusion The wave V response threshold of chirp -ABR is less than that of the click -ABR .The chirp-ABR is more advantageous than the click -ABR for assessing hearing threshold .
ABSTRACT
Objective To study the characteristics of auditory brainstem response by chirp and click stimuli in normal hearing children.Methods A total of 97 children (194 ears)with normal hearing were recruited,including 50 male (100 ears),and 47 female (94 ears).The CE-chirp and the click acoustic stimulation were used to,and the ABR waveforms and latencies were obtained.ResuIts The chirp-ABR Ⅰ wave recognition rate (36%)was significantly lower than that of click-ABR (100%).At 80 dB nHL,chirp-ABR V wave latency was shorter than click-ABR,the difference was statistically significant (P0.05).At 80 dB nHL,no statistical significance of two kinds of a-coustic stimulation of ABR V wave amplitude difference (P>0.05).At 50 dB nHL,chirp-ABR significantly in-creased than click-ABR V wave amplitude with statistically significant differences (P0.05 ).ConcIusion The chirp acoustic stimulation produced the larger response amplitude,and was faster,demonstrating the noticeable advantages to tes-ting children.
ABSTRACT
Objective To improve the estimation and the percentage of electrogastrogram(EGG)slow wave rhythm with power spectrum estimation and calculation rule set.Methods Chirp Z-transformation was introduced for estimation power spectrum of EGG,which can obtain both high frequency resolution and accurate estimation of power;while the power proportion of main frequency components in each segment was used to substitute for conventional method in time domain.Results The variance of proposed method was about one-eighth of that of conventional method.Incorporating the power proportion of main frequency components,the proposed method gave better results especially for those EGG signals in which abnormal frequencies appeared frequently.Conclusion As compared with the conventional method,the proposed method is less affected by segmentation process in estimating the percentage of EGG slow wave rhythm,which may promote future clinical applications.