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The speech auditory brainstem response (sABR) is a promising tool that can be used for objectively assessing auditory function. The main problem in obtaining the sABR is the high background noise, especially noise associated with general brain activity. In practice, a very long recording is needed to detect the sABR. We therefore propose a new detection method of the sABR based on spectral feature extraction that will reduce the detection time without reducing the accuracy. This method involves a constructed feature-frequency vector fed to an artificial neural network. The performance of the proposed method is compared to four other methods reported in the literature: optimal linear filtering, online estimator, Mutual Information, and artificial neural network based on discrete wavelet transforms and approximate entropy. All the methods were evaluated with several datasets of recorded and simulated sABRs ranging from extremely noisy to relatively clean. The proposed method performed very well in terms of sensitivity, specificity, and overall accuracy in detecting the sABR, compared with the other methods The reduction in the required recording time promises to facilitate the application of this measurement technique in clinical settings. [ABSTRACT FROM AUTHOR]

A variety of oscillometric algorithms have been recently proposed in the literature for estimation of blood pressure (BP). However, these algorithms possess specific strengths and weaknesses that should be taken into account before selecting the most appropriate one. In this paper, we propose a fusion method to exploit the advantages of the oscillometric algorithms and circumvent their limitations. The proposed fusion method is based on the computation of the weighted arithmetic mean of the oscillometric algorithms estimates, and the weights are obtained using a Bayesian approach by minimizing the mean square error. The proposed approach is used to fuse four different oscillometric blood pressure estimation algorithms. The performance of the proposed method is evaluated on a pilot dataset of 150 oscillometric recordings from 10 subjects. It is found that the mean error and standard deviation of error are reduced relative to the individual estimation algorithms by up to 7 mmHg and 3 mmHg in estimation of systolic pressure, respectively, and by up to 2 mmHg and 3 mmHg in estimation of diastolic pressure, respectively. [ABSTRACT FROM AUTHOR]

Background: Lung-to-finger circulation time of oxygenated blood during nocturnal periodic breathing in heart failure patients measured using polysomnography correlates negatively with cardiac function but possesses limited accuracy for cardiac output (CO) estimation.Methods and Results: CO was recalculated from lung-to-finger circulation time using a multivariable linear model with information on age and average overnight heart rate in 25 patients who underwent evaluation of heart failure. The multivariable model decreased the percentage error to 22.3% relative to invasive CO measured during cardiac catheterization.Conclusions: This improved automated noninvasive CO estimation using multiple variables meets a recently proposed performance criterion for clinical acceptability of noninvasive CO estimation, and compares very favorably with other available methods. [ABSTRACT FROM AUTHOR]

Summary: Objectives: Objective acoustic measures used to analyze phonatory dysfunction include shimmer and jitter. These measures are limited in that they do not take into account auditory processing. However, previous studies have indicated that shimmer may be processed differently along the tonotopic axis of the ear and, in particular, may be perceptually and physiologically significant around the third and fourth formants. Methods: This study investigated the relationship between shimmer around the first four formants (F1–F4) and in the broadband unfiltered speech waveform for 18 normal speakers from the voice disorders database of KayPENTAX. The voice samples were filtered around each formant with a bandwidth of 400Hz and then shimmer was assessed using five built-in different measures from Praat software. Results: Comparisons of means tests revealed that shimmer increases significantly with formant frequency from F1 to F4, for all shimmer measures. Furthermore, for all shimmer measures, shimmer in the unfiltered speech was significantly and more strongly correlated with shimmer around F1 (r = 0.45–0.61) and F2 (r = 0.69–0.74), significantly but more weakly correlated with F4 (r = 0.42–0.47), and not significantly correlated with F3. Conclusions: The findings indicate that there are differences in the shimmer found around the different formants and that shimmer information around F3 and F4 is not well captured in standard shimmer measurements based on the broadband unfiltered waveform. [Copyright &y& Elsevier]

Abstract: Steady-state responses were evoked by noise stimuli that alternated between two levels of interaural correlation ρ at a frequency f m. With ρ alternating between +1 and 0, responses at f m dropped steeply above 4Hz, but persisted up to 64Hz. Two time constants of 47 and 4.4ms with delays of 198 and 36ms, respectively, were obtained by fitting responses to a transfer function based on symmetric exponential windows. The longer time constant, possibly reflecting cortical integration, is consistent with perceptual binaural “sluggishness”. The shorter time constant may reflect running cross-correlation in the high brainstem or primary auditory cortex. Responses at 2f m peaked with an amplitude of 848±479nV (f m =4Hz). Investigation of this robust response revealed that: (1) changes in ρ and lateralization evoked similar responses, suggesting a common neural origin, (2) response was most dependent on stimulus frequencies below 1000Hz, but frequencies up to 4000Hz also contributed, and (3) when ρ alternated between [0.2–1] and 0, response amplitude varied linearly with ρ, and the physiological response threshold was close to the average behavioral threshold (ρ =0.31). This steady-state response may prove useful in the objective investigation of binaural hearing. [Copyright &y& Elsevier]

Background: Current oscillometric blood pressure measurement devices generally provide only singlepoint estimates for systolic and diastolic blood pressures and rarely provide confidence ranges for these estimates. A novel methodology to obtain confidence intervals (CIs) for systolic blood pressure (SBP) and diastolic blood pressure (DBP) estimates from a single oscillometric blood pressure measurement is presented. Methods: The proposed methodology utilizes the multiple regression technique to fuse optimally a set of SBP and DBP estimates obtained through different algorithms. However, the set of SBP and DBP estimates is a small number to determine the CI of each individual subject. To address this issue, the weighted bootstrap approach based on the multiple regression technique was used to generate a pseudo sample set for the SBP and the DBP. In this paper, the multiple regression technique can estimate the best-fitting surface of an efficient function that relates the input sample set as an independent vector to the auscultatory nurse measurement as a dependent vector to estimate regression coefficients. Consequently, the coefficients are assigned to an eight-sample set obtained from the fusion of different algorithms as optimally weighted parameters. CIs are also estimated using the conventional methods on the set of fused SBP and DBP estimates for comparison purposes. Results: The proposed method was applied to an experimental dataset of 85 patients. The results indicated that the proposed approach provides better blood pressure estimates than the existing algorithms and, in addition, is able to provide CIs for a single measurement. Conclusions: The CIs derived from the proposed scheme are much smaller than those calculated by conventional methods except for the pseudo maximum amplitude-envelope algorithm for both the SBP and the DBP, probably because of the decrease in the standard deviation through the increase in the pseudo measurements using the weighted bootstrap method for each subject. The proposed methodology is likely the only one currently available that can provide CIs for single-sample blood pressure measurements. [ABSTRACT FROM AUTHOR]