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PubMed1995

[Descriptive study of singing voices in children and women].

This paper is focused in the study of singing voices of both women and children, with the purpose of displaying and verify the existing differences of the two. In this article will be made clear than the affirmation made by Husson, Garde and Arribas (1962, 1973 and 1975, respectively) is not a dogmatic statement. The method used by us in order to drawn out the conclusions are the following: 1. A discriminative audio-perceptive technique requiring skilled experts in order to settle if the recorded voices belong to women, boys or girls. 2. Other technique adopted is founded in the spectral analysis of fragments recorded with the integrator of spectral density. The obtained results are as follows: The analysis audio-acoustic disclose differences between feminine voices and children voices. The experts could, with certainty, differentiate between each one of them (women 74%; children 79%). By means of the spectrum analysis was possible to verify that the prime objective of the spectral analysis employed is able to mimicking the global subjective impression received through the human auditory system.

Adolescent↗
PubMedDate not supplied

How the brain anticipates an attack: a study of neurophysiological periodicity in migraine.

We investigated cortical excitability and the pattern of arousal in migraine patients using contingent negative variation (CNV) and EEG power spectrum analysis performed before and after a migraine attack. Twenty females suffering from migraine without aura and 12 healthy controls were enrolled in the study. In the group of patients, the CNV, EEG power spectrum and hemispheric asymmetry analyses were performed 1-4 days before the first day of an attack and 4 days following the last day with migraine. The recordings in healthy subjects were carried out on a day chosen by the participants. The comparisons were made using non-parametric procedures. After an attack no difference was found between patients and controls in EEG power spectrum, hemispheric asymmetry or CNV components (with the exception of the beta 1 power, which was more pronounced in patients). Before an attack, however, a significant increase in the power of delta and theta frequency bands, in the alpha asymmetry, and in early CNV amplitude were observed. The patients differed from controls both in the extent of cortical excitability and in the arousal pattern found. In such a way migraine is characterized by periodic CNV and EEG power spectrum changes during the pain-free interval. The abnormalities in cortical excitability and arousal were only observed before an attack, and could be used to predict the next migraine episode. We assume that these changes reflect the increased susceptibility of the migrainous brain to precipitating factors and the neurophysiological readiness to generate an attack. The time duration since the last attack must be taken into account when performing studies in the field of migraine research.

Adult↗
PubMed2001

EMG-interference pattern analysis.

The EMG interference pattern, built up of single motor unit action potentials, may be analyzed subjectively, or objectively by computer aided, quantitative methods, like counting of zero-crossings, counting of spikes, amplitude measurements, integration of the area under the curve, decomposition techniques, power spectrum analysis and turn/amplitude analysis. Since the shape of the interference pattern of healthy muscles is dependent on age, sex, force, muscle, temperature, fatigue, fitness level, recording site and surrounding tissue, electrode type, sensitivity, filters, sampling frequency and threshold level, all methods of analyzing the IP have to be standardized. Quantitative methods of analyzing the EMG interference pattern may be used for monitoring botulinum toxin therapy of dystonia and spasticity, quantifying spontaneous activity, assessment of chronic muscle pain, neuro-urological and proctological function, and diagnosing neuromuscular disorders. For diagnostic purposes, the methods favored are those that use needle electrodes and do not require measurement or monitoring of muscle force. The most well-evaluated methods are those using turn/amplitude analysis, like the cloud methods and the peak-ratio analysis. Peak-ratio analysis has the advantage that reference limits are easy to obtain and that its utility is well established and confirmed by several investigations. Overall, automatic methods of EMG interference pattern analysis are powerful tools for diagnostic and non-diagnostic purposes.

Adult↗
PubMed1993

Rhythmic organization of the sound of infant crying.

The purpose of the present study was to examine the temporal morphology and rhythmic structure underlying the repeated bursts of expiratory sounds in a sustained bout of crying of twenty-three 1-month-old infants. Durations of expiratory sounds and bursts were determined from a 90-s bout of naturally occurring cries recorded in the home before feeding. Results indicated wide individual differences in temporal morphology between infants and within infant cry sounds. Binary spectrum analysis of the presence of expiratory sounds in the cry sound detected rhythms in temporal organization at a wide range of dominant frequencies. Spectral complexity (higher numbers of peaks in the power spectrum) was related to a longer time since infants were last fed and shorter expiratory sounds. Results emphasize the importance of viewing cries of young infants as dynamic signals. An ontogenetic history of the rhythms of infant cry sounds may contribute to understanding organismic and environmental experiences which contribute to development.

Child Behavior↗
PubMed1996

Purification of the 28 kD Protein from Maize Pollen and Studies on Its Properties.

A novel protein with ATPase activity was purified from the cytoplasmic extracts of maize pollen by acetone precipitation, ammonium sulfate fractionation, followed by DEAE-Sephadex A(50) and Mono S ion-exchange chromatography. The molecular weight was about 28 kD as determined by SDS-PAGE and the isoelectric point was pH 8.3 by IEF-PAGE. Western blotting analysis showed the 28 kD protein had no specific immuno-reactions with the anti-kinesin monoclonal or the anti-dynamin polyclonal antibodies. The maximum ultraviolet absorbance was at 278 nm, CD spectrum analysis showed the that 28 kD protein with the feature of a globulin. Pharmacological studies indicated that the enzyme activity was strongly inhibited by Na(3)VO(4) but insensitive to NEM. It was inhibited about 50% by NaF. Oligomycin, KNO(3) and ouabain had no effects on its ATPase activity.

Journal Article↗
PubMed2004

Stroke volume variability and heart rate power spectrum in relation to posture changes in healthy subjects.

BACKGROUND: Power spectrum analysis of heart rate variability (HRV) can be used to assess the state of sympathovagal balance-modulating sinus node activity. Stroke volume variability (SVV) probably reflects the dynamics of physiological control mechanisms over time. MATERIAL/METHODS: Power spectrum HRV and SVV were simultaneously measured in 44 healthy men. The values of the HRV and SVV parameters were compared for the supine and upright body positions in three age groups (I: 20-40; II: 40-60; III: >60 years old). The total power (TP) of the very low (VLF:<0.05 Hz), low (LF: 0.05-0.15 Hz) and high (HF: 0.15-0.5 Hz) HRV and SVV frequency bands were measured. The LF/HF and lnLF/lnHF ratios for HRV and SVV were calculated. RESULTS: The upright position caused a significant decrease in HRV in the HF and lnHF bands and an increase in the LF/HF and lnLF/HF ratios in all groups. SVV analysis for the supine position revealed significant differences in lnTP and HF values (between groups I and II) and in lnHF values (between groups I and II and I and III). SVV analysis for the upright position revealed differences in lnTP (between groups I and II and I and III), lnVLF (between groups I and III and I and III), lnLF (between groups I and II and I and III) and lnHF (between groups I and II and I and III). CONCLUSIONS: The combined analysis of HRV and SVV revealed different cardiovascular responses to postural stress in the three age groups considered.

Adult↗
PubMed2001

Dynamic analysis of inter-words time intervals: a method to analyze the structure of communicative signals.

Speech analyses are usually focused on words as signifiers ignoring inter-words time intervals (IWIs), which are related to the 'form' of speech, rather than to its 'content'. Applying the method of power spectrum analysis to inter-vocalizations time intervals of bird singing, underlying periodic processes were detected. In contrast, human IWIs revealed non-periodicity, which may be random or chaotic. To differentiate between these two possibilities, the non-linear dynamic methods of unstable periodic orbits and correlation dimension were applied to show that IWIs are characterized by a low dimensional chaotic attractor. Its correlation dimension of 3.2 +/- 1.1 suggests a minimum number of four variables underlying the system. The methods developed in the present communication can be further applied: (a) for the measurement of specific alterations in the processes underlying the form of speech in human disorders, i.e., schizophrenia, (b) for the assessment of normal and pathological developmental aspects of speech processes in children; (c) for comparing communicative signals between humans and other species.

Adult↗
PubMed2006

Estimation of HRV spectrogram using multiple window methods focussing on the high frequency power.

In this paper, the results of different multiple window spectrum analysis methods are compared in the estimation of heart rate variability (HRV) power spectra, in the high frequency band (HF), around 0.25 Hz, related to respiratory sinus arrhythmia (RSA). The evaluation is performed by simulating different spectrum shapes and peak frequency locations and calculating the mean squared error of a frequency range close around the strongest spectral peak. The results show that it is preferable to use the Peak Matched Multiple Windows in most situations, but the Welch method and the Sinusoid Multiple Windows can be as reliable in certain aspects.

Algorithms↗
PubMedDate not supplied

Autoregressive and cepstral analyses of motor unit action potentials.

Quantitative electromyographic signal analysis in the time domain for motor unit action potential (MUAP) classification and disease identification has been well documented over recent years. Considerable work has also been carried out in the frequency domain using classical power spectrum analysis techniques. Although MUAP autoregressive (AR) spectral analysis has been suggested as a diagnostic tool by a number of studies, it has not been thoroughly investigated yet. This work investigates the application of AR modeling and cepstral analysis for the diagnostic assessment of MUAPs recorded from normal (NOR) subjects and subjects suffering with motor neuron disease (MND) and myopathy (MYO). The following feature sets were extracted from the MUAP signal: (i) time domain measures, (ii) AR spectral measures, (iii) AR coefficients, and (iv) cepstral coefficients. Discriminative analysis of the individual features was carried out using the univariate and multiple covariance analysis methods. Both methods showed that: (i) the duration measure is the best discriminative feature among the time domain parameters, and (ii) the median frequency is the best discriminative feature among the AR spectral measures. Furthermore, the classification performance of the above four feature sets was investigated for three classes (NOR, MND and MYO) using artificial neural networks. Results showed that the highest diagnostic yield was obtained with the time domain measures followed by the cepstral coefficients, the AR spectral parameters, and the AR coefficients. In conclusion, MUAP autoregressive and cepstral analyses combined with time domain analysis provide useful information in the assessment of myopathology.

Action Potentials↗
PubMed2000

[A contrast analysis of four phonation methods frequency between patients with glottis closure disturbance and normal human].

OBJECTIVE: To find out frequency change parameters of four phonation methods (minimum, natural, maximum and falsetto maximum voices) and different maximum phonation persistent time (MPPT) of them in patients with glottis closure disturbance (GCD). METHOD: With frequency spectrum analysis, the frequencies of four phonation methods were studied in functional GCD patients (150 cases) and normal human (60 cases). RESULT: There were marked differences of voice frequencies between them not only in male but also in 5 female. And with the prolongation of MPPT, the voice frequencies also changed. CONCLUSION: The functions of both low and high voices decline in GCD patients. With the prolongation of MPPT, the functions of low and high voices strengthen in GCD patients.

Adolescent↗
PubMed1990

Correlations of acoustic tissue typing of malignant melanoma and histopathologic features as a predictor of death.

Forty-six eyes with uveal melanoma were scanned with a computerized diagnostic ultrasound system before enucleation, and light microscope sections were obtained. Tumors were characterized by ultrasonically measured dimensions and power spectrum analysis, which provided information not available in conventional A- or B-scan ultrasonography. Histopathologic features, including cell clustering pattern, cell type, pigmentation, vascularity, and necrosis, were quantified. Statistically significant correlations were found between parameters derived from the power spectrum and histologic characteristics. Patients were followed up for up to ten years with 14 deaths occurring because of metastases. Using a Cox relative risk model with histopathologic data, a risk model comprising pigmentation and cell type (P less than .0001) was obtained. Using ultrasonic characteristics, a model comprising tumor volume and scatterer concentration (P = .0062) was obtained. The results suggest that ultrasonic tissue characterization and three-dimensional biometry may provide improved in vivo prognostic indicators for uveal melanoma.

Eye Enucleation↗
PubMed2000

Parametric estimation of the continuous non-stationary spectrum and its dynamics in surface EMG studies.

Frequency spectrum of surface electromyographic signals (SEMGs) exhibit a non-stationary nature even in the case of constant level isometric muscle contractions due to changes related to muscle fatigue processes. These changes can be evaluated by methods for estimation of time-varying (TV) spectrum. The most widely adopted non-parametric approach is a short time Fourier transform (STFT), from which changes of mean frequency (MF) as well as other parameters for qualitative description of spectrum variation can be calculated. Similar idea of a sliding-window generalisation can also be used in case of parametric spectrum analysis methods. We applied such approach to obtain TV linear models of SEMGs, although its large variance due to independence of estimations in consequent windows represents a major drawback. This variance causes unrealistic abrupt changes in the curve of overall spectrum dynamics, calculated either as the second derivative of the MF or, as we propose, autoregressive moving average (ARMA) distance between subsequent linear models forming the TV parametric spectrum. A smoother estimation is therefore sought and another method shows to be superior over a simple sliding window technique. It supposes that trajectories of TV linear model coefficients can be described as linear combinations of known basis functions. We demonstrate that the later method is very appropriate for description of slowly changing spectra of SEMGs and that dynamics measures obtained from such estimations can be used as an additional indication of the fatigue process.

Electromyography↗
PubMed1989

Spectral correlates of glottal voice source waveform characteristics.

The relationships between the waveform and the spectrum of the pulsating transglottal airflow during vowel phonation are analyzed in singers and nonsingers. The waveform, called the flow glottogram, is analyzed by means of inverse filtering, and the spectrum is determined either directly, by submitting the flow glottogram to spectrum analysis, or indirectly, by measuring spectral changes accompanying phonatory changes under conditions of constant vowel articulation. The peak-to-peak amplitude of the flow glottogram pulses shows a strong relationship with the amplitude of the source spectrum fundamental and varies considerably during phonation, presumably depending on the degree of glottal ab/adduction. The negative peak amplitude of the differentiated flow glottogram shows a high correlation with the sound pressure level of the vowel.

Adult↗
PubMed1996

Twenty-four-hour pattern of blood pressure and spectral analysis of heart rate variability in diabetic patients with various degrees of autonomic neuropathy. Comparison to standard cardiovascular tests.

We performed four cardiovascular tests of autonomic function (deep breathing, lying to standing, Valsalva manoeuvre, postural hypotension) and simultaneous 24h recordings of blood pressure (BP) and ECG in 35 normotensive diabetic subjects. Autoregressive power spectrum analysis of RR interval variability was applied to 24h ECG recordings to obtain for day and night periods power of low- (0.03-0.15 Hz, LF) and high-frequency (0.18- 0.40 Hz, HF) components, relative markers of sympathetic and vagal activity respectively, and their ratio (LF/HF), assumed as index of sympathovagal balance. Eighteen patients showed normal cardiovascular tests, 6 patients one abnormal heart rate test, 5 patients two abnormal heart rate tests, and 6 patients also abnormal postural hypotension test. In diabetic patients with increasing degree of autonomic neuropathy, there was a progressive reduction of day-night change in systolic BP (p < 0.01), of LF during the day (p < 0.01), of HF during the night (p < 0.04), of day-night change in HF (p < 0.02), and of day-night change in HF/LF (p < 0.03). Day-night change in systolic BP was related to postural hypotension (p < 0.001) and to deep breathing (p < 0.01). Day LF was related to lying to standing (p < 0.001), to postural hypotension (p < 0.005) and to deep breathing (p < 0.007). Night HF was related to deep breathing (p < 0.0002) and to lying to standing (p < 0.02). Day-night change in HF/LF was slightly related to deep breathing, lying to standing, and to postural hypotension (p < 0.04). In a multiple regression analysis including age, diabetes duration, and cardiovascular tests as independent variables, day-night change in BP and day LF were only related to postural hypotension, whereas night HF was related to deep breathing. In conclusion, in diabetic patients with increasing autonomic damage, there is a progressive impairment of nocturnal fall of BP and of sympathetic activity during the day, blunted nocturnal increase of vagal activity and lower circadian variation in sympathovagal balance. The significant but not very close correlation of day-night pattern of BP and sympathovagal activity to standard cardiovascular reflex tests, supports the independent usefulness of 24h BP monitoring and spectral analysis of heart rate variability in diabetic neuropathy.

Adult↗
PubMed1987

Capillary chromatographic analysis of volatile organic compounds in the indoor environment.

The wide variety of volatile organic compounds found in the indoor environment can present a difficult chromatographic problem for the analyst. Capillary-column gas chromatography is required to achieve adequate separation. Thermal desorption/capillary gas chromatography/mass spectrometry is usually the preferred method for broad spectrum analysis of the volatile organics detected indoors. Cryogenic trapping is required for capillary gas chromatographic analysis of the more volatile components.

Air Pollutants↗
PubMed1994

[Observation of electroencephalogram spectrum changes over one year of Qigong training].

Using spectrum analysis method, the electroencephalogram (EEG) changes of the students who first learned Zhanzhuang Qigong in comparing with the students who did not practice at all were observed, over a period of one year. The results showed that the spectrum of EEG did not change significantly after half year training, but one year later, the alpha index of right frontal and right temporal regions decreased significantly (P < 0.05), and the beta index of right frontal and right temporal regions decreased significantly (P < 0.05). It was indicated that there was a higher tendency of EEG synchyonization, the brain activity changed from "active" to "harmonious" and "calm". It was a gradually adjusting process.

Adolescent↗
PubMed1990

Computerized analysis of antepartum fetal heart rate tracings in normal pregnancies (version 88/2.29).

A computerized system is developed for the interpretation of antepartum fetal heart-rate monitoring. Various parameters are described to define the cardiotocograms. The pattern of the tracing is defined as saltatory, undulatory, reduced undulatory or silent according to the results of the spectrum analysis. Three different baselines including simple average baseline, real baseline and basecurve are described for each tracing. Spontaneous and fetal movement related accelerations and decelerations are also defined. Tracings from 33 normal pregnancies with normal outcome were studied and the distribution of parameters for each gestational week (28th to 40th) was defined. The real baseline of fetal heart rate was 141.5 +/- 8.5 between the 28th and 40th gestational week. 75% of the cardiotocograms were found to obtain fetal movement. It has also been observed that in normal pregnancies the general pattern of the tracings is undulatory or undulatory/saltatory.

Female↗