Community noise—jet engine with afterburner Approximately what sound pressure level (SPL) in decibels is measured about 100 metres from a jet engine operating with afterburner?

Introduction / Context:
Environmental noise assessment requires order-of-magnitude understanding of typical sources. Jet engines, especially with afterburners engaged, are among the loudest continuous man-made sources encountered near airports and testing facilities.

Given Data / Assumptions:

• Distance from source: about 100 m in free field conditions.
• Source: jet engine with afterburner (very high thrust and exhaust velocity).
• Reference is A-weighted or overall SPL estimates for practical comparisons.

Concept / Approach:
Typical SPL values decay with distance approximately according to spherical spreading and atmospheric absorption, but the levels remain extremely high close to the source. Around 100 m, SPLs near 140 dB are reported for afterburning engines, which is near the threshold of pain and requires stringent hearing protection and exclusion zones.

Step-by-Step Solution:

Verification / Alternative check:
Noise control literature lists 130–150 dB ranges near military afterburning jets at tens to hundreds of metres, making 140 dB a reasonable central figure.

Why Other Options Are Wrong:

• 120 dB: too low for afterburners at 100 m.
• 170 or 200 dB: levels typical of explosions/shock fronts at much closer ranges, not sustained engine operation at 100 m.

Common Pitfalls:
Ignoring logarithmic decibel scaling; small numeric differences represent large intensity changes.

Final Answer:
140 dB