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IntroductionCarbonated water (CarbW) affects the swallowing function associated with the action of the brainstem. In addition, CarbW ingestion promotes mean blood flow in the middle cerebral artery, which is associated with blood flow to the frontal and temporal lobes. In this milieu, studies regarding the effect of drinking CarbW on brain activity are of significance. In the present study, we compared the changes in cerebral blood flow in the frontal region before and after the ingestion of CarbW or uncarbonated water (SW).MethodsNear-infrared spectroscopy was used to continuously measure the cerebral blood flow at 22 channels in the frontal region of 13 healthy young adults for 10 min before and after the ingestion of CarbW or SW. We statistically compared the changes in oxyhemoglobin concentration before and after the ingestion of CarbW or SW.ResultsCompared with that before CarbW ingestion, the oxyhemoglobin concentration in the left frontal region increased after CarbW ingestion. In particular, a significant increase (p

The time-frequency masking approach in blind speech extraction consists of two main steps: feature clustering in a space spanned over delay-time and attenuation rate, and spectrogram masking in order to reconstruct the sources. Usually a binary mask is generated under the strong W-disjoint orthogonal (WDO) assumption (disjoint orthogonal representations in the frequency domain). In practice, this assumption is most often violated leading to weak quality of reconstructed sources. In this paper we propose the WDO to be relaxed by allowing some frequency bins to be shared by both sources. As we detect instantaneous fundamental frequencies the mask creation is supported by exploring a harmonic structure of speech. The proposed method is proved to be effective and reliable in experiments with both simulated and real acquired mixtures.

We are developing two crucial improvements on the time-frequency masking approach to the blind speech separation of underdetermined mixtures when processing anechoic and echoic mixtures. First, the proposed method copes with the usually large amount of delay estimation error that appears in a low frequency band. This step generates a restrictive mask for phase delays on the basis of local and global energy distribution analysis. This mask allows the selected cells to contribute to the orientation histogram. Second, the strong WDO assumption (disjoint orthogonal frequency domain) is relaxed by allowing some frequency bins to be shared by both sources. By detecting fundamental frequencies of speakers at instantaneous time points, mask creation is supported by exploring their harmonic frequencies. The proposed method is proved to be effective and reliable in conducting experiments with both simulated and real-life mixtures. Santrauka Straipsnyje nagrinėjamas aklasis signalų šaltinių išskyrimas apdorojant signalų mišinius su aido efektu ar be jo. Detaliai pristatomi matematiškai bei eksperimentų su dirbtiniais ir realiais šnekos duomenimis rezultatais pagrindžiami du esminiai šio metodo patobulinimai. Pirmasis patobulinimas leidžia sumažinti vėlinimo žemuose dažniuose įtaką šnekos signalo išskyrimo klaidai. Antrasis patobulinimas, paremtas kalbėtojo pagrin­dinio dažnio sekimu, leidžia algoritmui išnaudoti tas pačias dažnių sritis skirtingiems signalų šaltiniams išskirti. Raktiniai žodžiai: šaltinių aklasis atskyrimas; histogramos klasterizavimas; spektrogramos analizė; kalbos rekonstravimas; maskavimas laiko ir dažnių skalėje