The dB meter will show that both rifles produce the same decibel level of noise.
2.
What a dB meter does not show is that, although both rifles produce the same peak sound pressure level ( SPL ), the . 300 Winchester Magnum holds its peak duration longer meaning that the . 300 Winchester Magnum sound remains at full value longer, while the . 308 peaks and falls off more quickly.
3.
In a physical sense, dB meters essentially take a short-time average ( RMS intensity of a sonic signal or impulse ) over a specified period of time ( sampling rate ), and do not take into account the rate of increase of the sound wave packet ( first derivative of packet envelope ), which would in practice provide a better sense of the human perception of sound.
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