Living in a box: Understanding acoustic parameters in the NICU environment

BackgroundIn the last years, a significant body of scientific literature was dedicated to the noisy environment preterm-born infants experience during their admission to Neonatal Intensive Care Units (NICUs). Nonetheless, specific data on sound characteristics within and outside the incubator are missing. Therefore, this study aimed to shed light on noise level and sound characteristics within the incubator, considering the following domain: environmental noise, incubator handling, and respiratory support.MethodsThe study was performed at the Pediatric Simulation Center at the Medical University of Vienna. Evaluation of noise levels inside and outside the incubator was performed using current signal analysis libraries and toolboxes, and differences between dBA and dBSPL values for the same acoustic noises were investigated. Noise level results were furthermore classed within previously reported sound levels derived from a literature survey. In addition, sound characteristics were evaluated by means of more than 70 temporal, spectral, and modulatory timbre features.ResultsOur results show high noise levels related to various real-life situations within the NICU environment. Differences have been observed between A weighted (dBA) and unweighted (dBSPL) values for the same acoustic stimulus. Sonically, the incubator showed a dampening effect on sounds (less high frequency components, less brightness/sharpness, less roughness, and noisiness). However, a strong tonal booming component was noticeable, caused by the resonance inside the incubator cavity. Measurements and a numerical model identified a resonance of the incubator at 97 Hz and a reinforcement of the sound components in this range of up to 28 dB.ConclusionSound characteristics, the strong low-frequency incubator resonance, and levels in dBSPL should be at the forefront of both the development and promotion of incubators when helping to preserve the hearing of premature infants

Rotierender optischer Positions- und Winkelsensor

This work presents a sensor which is able to measure the height and the angle of the reference point of the sensor in respect to a laser reference. This is done by measuring the time between laser pulses and a hall sensor as a reference. Also, the implementation of the measurement failure handling in hardware and software is discussed. With the presented sensor a standard deviation of 0.131 mm at a measurement range of ±92 mm can be achieved. The maximum deviation of the mean values of the different measurement methods is 0.393 mm. If there is no need for a high bandwidth of the sensor, these values can be further decreased by calculating average values of the measurement signal.In dieser Arbeit wird ein Sensorprinzip vorgestellt, welches die Höhe und den Winkel des Referenzpunkts des Sensors in Bezug auf eine Laserreferenz optisch messen kann. Dies wird durch eine Zeitmessung zwischen den Laserimpulsen und einem Hallimpuls als Referenz erreicht. Es werden Hard- und Softwaremaßnahmen zur Erkennung und Unterdrückung von Störungen vorgestellt und implementiert. Mit dem Sensorprinzip kann eine Standardabweichung von 0,131 mm bei einem Messbereich von ±92 mm erreicht werden, wobei sich die Mittelwerte der unterschiedlichen Messmethoden um max. 0,393 mm unterscheiden. Bei geringer Anforderung an die Messfrequenz des Sensors können diese Werte durch Mittelwertbildung noch weiter verbessert werden.Österreichische Forschungsförderungsgesellschaft mbH (FFG