Literature Review On Noise And Smartphone Noise

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2 Literature Review
Based on the research design and challenges for this dissertation, the scope of the literature review includes three key areas that will be discussed hereafter:
1. Noise and smartphone noise data collection. o Noise and indices. o Noise data collection applications. o Participatory sensing.
2. Noise mapping. o Noise data. o Predicting Noise Exposure Levels.
3. Estimating a total number of buildings and population exposed to noise levels >55 dB.
2.1 Noise and Smartphone Noise Data Collection
2.1.1 Noise
Sound waves oscillate air molecules producing alternating sound pressure levels. The varying frequencies and amplitude of these sound waves can be detected by the human ear. To the human ear, the frequency is perceived as pitch and amplitude perceived as loudness (Bies and Hanson, 2003). Sound pressure level is commonly expressed using a weighted system because the highest sound pressure level tolerated by the human ear is 10 million times larger than the smallest. There are many noise weightings which are a spectrum of amplitude vs frequency, designed to measure specific frequency ranges. When measuring environmental noise it is practical to measure only the frequencies that the human ear can hear. Epidemiological studies have indicated that the human auditory system is capable of detecting a frequency range between 20 and 20,000 Hz and is most sensitive to frequencies between 1 and 5 kHz (Peters et al., 2011). Considering this, a noise weighting system
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