Browsing by Subject "Noise"

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  • Mutanen, Tuomas P.; Metsomaa, Johanna; Liljander, Sara; Ilmoniemi, Risto J. (2018)
    Electroencephalography (EEG) and magnetoencephalography (MEG) often suffer from noise-and artifact-contaminated channels and trials. Conventionally, EEG and MEG data are inspected visually and cleaned accordingly, e.g., by identifying and rejecting the so-called "bad" channels. This approach has several shortcomings: data inspection is laborious, the rejection criteria are subjective, and the process does not fully utilize all the information in the collected data. Here, we present noise-cleaning methods based on modeling the multi-sensor and multi-trial data. These approaches offer objective, automatic, and robust removal of noise and disturbances by taking into account the sensor-or trial-specific signal-to-noise ratios. We introduce a method called the source-estimate-utilizing noise-discarding algorithm (the SOUND algorithm). SOUND employs anatomical information of the head to cross-validate the data between the sensors. As a result, we are able to identify and suppress noise and artifacts in EEG and MEG. Furthermore, we discuss the theoretical background of SOUND and show that it is a special case of the well-known Wiener estimators. We explain how a completely data-driven Wiener estimator (DDWiener) can be used when no anatomical information is available. DDWiener is easily applicable to any linear multivariate problem; as a demonstrative example, we show how DDWiener can be utilized when estimating event-related EEG/MEG responses. We validated the performance of SOUND with simulations and by applying SOUND to multiple EEG and MEG datasets. SOUND considerably improved the data quality, exceeding the performance of the widely used channel-rejection and interpolation scheme. SOUND also helped in localizing the underlying neural activity by preventing noise from contaminating the source estimates. SOUND can be used to detect and reject noise in functional brain data, enabling improved identification of active brain areas.
  • Muhammad, Sajjad; Lehecka, Martin; Huhtakangas, Justiina; Jahromi, Behnam Rezai; Niemelä, Mika; Hafez, Ahmad (2019)
    BackgroundNeurosurgeons are vulnerable to additional noise in their natural operating environment. Noise exposure is associated with reduced cognitive function, inability to concentrate, and nervousness. Mediation music provides an opportunity to create a calmer environment which may reduce stress during surgery.MethodsA pilot study was performed to find a suitable task, meditation music of surgeon's choice, and operation noise and to reach a certain level of training. For the main experiment, two neurosurgeons with different microsurgical experience used real operation noise and meditation music with delta waves as mediating music. Each surgeon performed 10 training bypasses (five with noise and five with music) with 16 stitches in each bypass. The total time to complete 16 stitches, a number of unachieved movements (N.U.Ms), length of thread consumed, and distribution of the stitches were quantified from the recorded videos and compared in both groups.ResultsA N.U.Ms were significantly reduced from 10938 with operation room (OR) noise to 38 +/- 13 (p
  • WANG, Donald (2020)
    Atrahasis is the protagonist of an 18th-century BC Akkadian epic found in various versions on clay tablets. It has many parallels with the biblical account of creation in Genesis. This paper will closely examine the meaning and usage of spirit in Atrahasis. The point is that spirit in Atrahasis plays a vital role in the creation account of human beings and the spirit performs a bridging role in the overarching narrative of rebellion, creation, and flood.
  • Sivonen, Ville; Willberg, Tytti; Sinkkonen, Saku T.; Aarnisalo, Antti A.; Dietz, Aarno (2017)
    Väestön ikääntyessä kuulonalenemien esiintyvyys ja tarve vaikuttavaan kuulonkuntoutukseen kasvavat. Hyvän yleiskäsityksen kuulosta antavat äänieriön hiljaisuudessa tehtävät perustutkimukset, äänesaudiometria ja puheaudiometria. Ne eivät kuitenkaan välttämättä kuvasta kuulonaleneman aiheuttamaa haittaa hälyisissä tilanteissa. Uuden suomenkielisen hälylausetestin avulla voidaan tutkia aiempaa paremmin aikuisten kuntoutuspotilaiden kuulonvaraista selviämistä arjessa. Suomenkielisen lasten hälypuhetestin validointi on meneillään.