Microphone signals for OSHA workplace monitoring, vibration analysis, and acoustic event detection.
An important application of sound data acquisition is monitoring sound levels in the workplace. The Occupational Safety and Health Administration (OSHA) limits the maximum sound levels and the duration at which sound levels can be sustained. For example, OSHA limits sound levels at 90 dBA to 8 hours. 100 dBA is limited to 15 minutes. For every 3 decibels over 85 dbA, the allowed exposure time is decreased by half. By using a data acquisition system coupled with a microphone, employers can ensure they don’t exceed OSHA limitations.
Sound frequency (Hz) and sound intensity (dB) can be directly measured with an appropriate sensor and DAQ. The microphone is a well known sensor to convert sound waves into analog electrical signals. Often modern compact microphone assemblies contain an amplifier to convert the mechanical vibration mode (electret, piezo, or coil) to a measurable voltage. This voltage can then be logged directly by a DAQ or amplified, filtered or integrated for a particular application. Afterward the data logged by the DAQ can be converted into the frequency domain for further analysis or even simply recorded for playback.
Recommended DAQ
Recommended DAQ: Nyquist 2
Audio-bandwidth measurement (up to 10 kHz on the Nyquist line) needs the higher sample rate and resolution NQ2 provides for clean FFT analysis.
Code example
The DAQiFi Python SDK exposes a property-based API. Below is a minimal stream — discover the device, enable an analog-input channel, and print samples at 1 kS/s.
from daqifi import DAQiFiDevice
with DAQiFiDevice.discover_first() as dev:
dev.channels.ai0.enable()
for sample in dev.stream(rate_hz=1000):
print(sample)
For C#, Java, LabVIEW, or Node.js examples, see the open-source stack page or jump straight into the reference example app on GitHub.
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