Folks may find the linked video interesting: it is on the difference between "noise cancellation" and "electronic hearing protection:"
This is a helpful video in distinguishing between these two modalities.
Tl;dr, the point is that most 'electronic hearing protection' muffs do not operate in the mode of "noise cancellation" insofar as the speakers are not generating an out-of-phase waveform of the same amplitude and frequency as the gunshot or other loud sound (that is, not employing destructive interference). Rather, the circuitry is amplifying low amplitude (volume) noises picked up by the microphones and recreates this waveform via the internal speakers. This process is effectively cut-off when the exterior amplitude (volume) passes a certain threshold.
But the actual and only dB "reduction" from an external source is that passively rendered by the muffs just as any passive muffs would do. In other words, the electronics have nothing to do with "protection," but, rather, in amplifying low-level sounds e.g. conversations or movement. They allow one to hear low level noises such as conversation better: they don't mitigate high dB sources other than passively.
My only fuss with the video is the fellow was using transverse waveforms to illustrate his point whereas sound waves are compressive or longitudinal. To be fair, it is a lot easier to illustrate the former, but he might have quickly acknowledged the point.
This is a helpful video in distinguishing between these two modalities.
Tl;dr, the point is that most 'electronic hearing protection' muffs do not operate in the mode of "noise cancellation" insofar as the speakers are not generating an out-of-phase waveform of the same amplitude and frequency as the gunshot or other loud sound (that is, not employing destructive interference). Rather, the circuitry is amplifying low amplitude (volume) noises picked up by the microphones and recreates this waveform via the internal speakers. This process is effectively cut-off when the exterior amplitude (volume) passes a certain threshold.
But the actual and only dB "reduction" from an external source is that passively rendered by the muffs just as any passive muffs would do. In other words, the electronics have nothing to do with "protection," but, rather, in amplifying low-level sounds e.g. conversations or movement. They allow one to hear low level noises such as conversation better: they don't mitigate high dB sources other than passively.
My only fuss with the video is the fellow was using transverse waveforms to illustrate his point whereas sound waves are compressive or longitudinal. To be fair, it is a lot easier to illustrate the former, but he might have quickly acknowledged the point.
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