Instruction manual

115
Technical Notes
The "Slow" time weighting setting is suitable for measuring the average of noise with
fairly constant levels. Aircraft noise and high-speed train noise is usually transient noise
with high fluctuation, but here the "Slow" setting is used to determine the maximum level
for each noise event.
The "10 ms" setting of the NA-27 results in a very short time weighting, enabling the
meter to closely follow noise fluctuations.
The "Imp (Impulse)" setting enables the meter to track noise bursts of very short duration.
In the "Peak (Peak Hold)" condition, no averaging is carried out, and the peak value of the
frequency-weighted sound pressure waveform is displayed.