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The neural correlates of how attended speech is internally represented are described, shedding light on the ‘cocktail party problem’. Heard instinct The 'cocktail-party problem' — the question of what goes on in our brains when we listen selectively for one person's voice while ignoring many others — has puzzled researchers from various disciplines for years. Using electrophysiological recordings from neurosurgery patients listening to two speakers simultaneously, Nima Mesgarani and Edward Chang determine the neural correlates associated with the internal representation of attended speech. They find that the neural responses in the auditory cortex represent the attended voice robustly, almost as if the second voice were not there. With these patterns established, a simple algorithm trained on various speakers predicts which stimulus a subject is attending to, on the basis of the patterns emerging in the secondary auditory cortex. These results suggest that speech representation in the brain reflects not only the acoustic environment, but also the listener's understanding of these signals. As well as shedding light on a long-standing neurobiological problem, this work may give clues as to how automatic speech recognition might be improved to cope with more than one talker. Humans possess a remarkable ability to attend to a single speaker’s voice in a multi-talker background 1 , 2 , 3 . How the auditory system manages to extract intelligible speech under such acoustically complex and adverse listening conditions is not known, and, indeed, it is not clear how attended speech is internally represented 4 , 5 . Here, using multi-electrode surface recordings from the cortex of subjects engaged in a listening task with two simultaneous speakers, we demonstrate that population responses in non-primary human auditory cortex encode critical features of attended speech: speech spectrograms reconstructed based on cortical responses to the mixture of speakers reveal the salient spectral and temporal features of the attended speaker, as if subjects were listening to that speaker alone. A simple classifier trained solely on examples of single speakers can decode both attended words and speaker identity. We find that task performance is well predicted by a rapid increase in attention-modulated neural selectivity across both single-electrode and population-level cortical responses. These findings demonstrate that the cortical representation of speech does not merely reflect the external acoustic environment, but instead gives rise to the perceptual aspects relevant for the listener’s intended goal.

A cleanroom is a highly controlled environment; therefore, air quality is of significant concern, and specific physical and microbiological requirements must meet the standard. In addition to the number of particles, another critical parameter in a cleanroom is temperature. USP (The United States Pharmacopeia) 797 recommends that the temperature of a cleanroom be around 20 °C. Air quality is achieved through several parameters and components, such as using a high-efficiency particulate air filter (HEPA), the amount of fresh air entering the room, temperature, pressure difference, and airflow direction. In this study, the cooling load of the room for the filling and sealing process was calculated, and the airflow and temperature distribution patterns between two parameters of the return air grille (RAG) position were compared using Computational Fluid Dynamics (CFD). The first parameter, RAG 1, was placed above the ceiling, while the second parameter, RAG 2, was set on the sidewall. Based on the results of the study, it was found that the heat load generated from the room was 6.99 kW with a cooling coil capacity amounting to 10.77 kW. Moreover, the supply airflow rate was 371.66 l/s. Based on the results of the simulation modelling, it was found that the RAG positioned on the sidewall was more ideal than the RAG positioned above the ceiling since the temperature was more evenly distributed in the room where the RAG was positioned on the sidewall.

The biotech cleanroom industry presents a biological basis for living organisms or their components (bacteria or enzymes) to produce helpful medicine. However, biotech industries such as vaccine production need a clean critical environment and contamination control that is always a vital concern for the manufacturing process. This study investigates a biotech cleanroom through a comprehensive field measurement and numerical simulation. The field measurement test results conformed to the design specification to satisfactorily meet with the cleanroom standard of PIC/S and EU GMP. Furthermore, the field measurement data were used as a basic validation and boundary condition for numerical simulation. The numerical simulation results revealed that the concentration distribution in case 1 as a baseline case showed satisfactory results, with a removal efficiency of 75.2% and ventilation efficiency of 80%. However, there was still a high concentration accumulated in certain areas. The improvement strategy was analyzed through non-unidirectional flow ventilation with different face velocities and by adding one return air grille for case 2 and two return air grilles for case 3. The results revealed that case 2 presented the best results in this study, with a removal efficiency of 86.7% and ventilation efficiency of 82% when supplying air velocity at 0.2 m/s. In addition, increasing the supply air velocity to 0.3 m/s could enhance removal ventilation by around 19% and ventilation efficiency by around 5%.

Controlling contamination via proper airflow distribution in an operating room becomes vital to ensure the reliable surgery process. The heating, ventilation, and air conditioning (HVAC) systems significantly influence the operating room environment, including temperature, relative humidity, pressurization, particle counts, filtration, and ventilation rate. A full-scale operating room has been investigated extensively through field measurements and numerical analyses. Computational fluid dynamics (CFD) simulation was conducted and verified with the field measurement data. The simulation was analyzed with three different operating room schemes, including at-rest conditions (case 1), normal operational conditions with personnel (case 2), and actual conditions with personnel inside and some medical equipment blocking the return air (case 3). The concentration decay method was used to evaluate this study. The results revealed that the contamination concentration in case 1 could be diluted quickly with the average value of 404 ppm, whereas the concentration in case 2 slightly increased while performing a surgery with the average value of 420 ppm. The return air grilles in case 3, blocked by obstacles from some medical equipment, resulted in the average concentration value of 474 ppm. Other than that, the contaminant dilution could be obstructed dramatically, which revealed that proper and smooth airflow distribution is essential for contamination control. The ventilation efficiency of case 2 and case 3 dropped around 6% and 17.91% compared to case 1 in the unoccupied and ideal condition. Ventilation efficiency also decreased along with decreasing the air change rate per hour (ACH), while with increasing ACH, the ventilation efficiency in case 3 actually increased, approaching case 2 in the ideal condition.