Can a simple audio recording near a target reveal a shooter's distance?

1. ANSWER
Yes, you can estimate the shooter's distance using a microphone near the target by measuring the time delay (Δt) between the supersonic crack (bullet's shock wave as it passes nearby) and the thump/bang (muzzle blast sound arriving later). The physics: bullet travels faster than sound (~800 m/s for rifle rounds vs. ~343-350 m/s sound speed), so crack arrives first; delay depends on distance (d) via approximate formula:
d ≈ Δt × (1/c - 1/v), where c = speed of sound, v = average bullet velocity.
Rough rules: 0.5s delay ≈ 300 yards; 1s ≈ 600 yards (FM 23-10 manual). Accuracy: ~10-20% error due to bullet drag, weather, mic position; validated in forensics (e.g., Trump rally: 217 ms → ~135 m).[1][2][3]

2. EVIDENCE

• Forensic analysis (Trump rally, 2024): Podium mic near target recorded ~217 ms between crack (shock wave) and thump (muzzle blast). Using c=350 m/s, v=800 m/s (AR-15 .223 Rem, avg. 795 m/s over distance): d ≈ 0.217 × (1/350 - 1/800) ≈ 135 m, matching rooftop shooter location. Robert C. Maher, Montana State Univ. prof., JAES paper (advance pub. Nov. 2025, analysis from Jul. 13, 2024).[1]
• Military "Crack-Thump" method: US Army FM 23-10: Time crack (bullet pass) to thump (muzzle sound); 1s ≈ 600 yards, 0.5s ≈ 300 yards for typical supersonic calibers (e.g., 5.56mm, v~2-3x sound speed). Assumes ~340 m/s sound, bullet drag; effective <500m before transonic effects. YouTube explainer (2026 crawl, cites manual).[3]
• Acoustics.org (Nov. 5, 2024): Maher confirms crack-then-bang in downrange mic; tiny Δt yields ~130m in rally audio, verified by evidence. Same author as JAES.[2]
  No conflicting info; peer-reviewed/academic/military sources consistent. Calculators exist (e.g., superfly.co.nz/ct.htm) for inputs like v, Δt, c.[4]

3. CREDIBILITY
9/10. Strong: peer-reviewed forensics (JAES), military doctrine (FM 23-10), real-world validation (Trump rally matched physical evidence). Minor limits: needs known/estimated v, weather data; less precise >500m or subsonic ammo.

4. BIAS
CENTER. Sources: academic (Montana State Univ., Acoustical Society), US Army manual, neutral forensics—no political slant.[1][2][3]