  Acoustic noise has adverse effects on human activities. Aside from hearing
impairment and stress-related illnesses, it can also interfere with spoken
communication, reduce human performance and affect the quality of life. As
urbanization is intensifying, the potential benefits of reducing noise
pollution in smart-city environments are extensive. Noise levels can be
collected and analyzed using a wireless sensor network which can monitor the
noise level by using microphones. However, every wireless system struggles in
terms of the battery requirements needed for continuous data collection and
monitoring. In this paper, the design of a testbed for a smart microphone
system is presented. To save power, a microcontroller and an Analog-to-Digital
Converter (ADC) dynamically switch between high and low power modes in response
to environmental noise. Specifically, the high powered components are triggered
by a spike in the acoustic noise level. Three wireless technologies, WiFi (2.4
GHz), Bluetooth Low Energy (BLE) 4.0 and Zigbee were examined. According to the
results, the power consumption of a node can be lowered by 97% when idle based
on the testbed.
