## Summary
- Normalises all 20 SFX files to -22 LUFS with true peak ≤ -2 dBFS
- Collapses a ~20dB loudness spread (hydrogen-hit at -14.94 LUFS vs
sam-hit at -34.56 LUFS) into ~2dB
- Previously jarring hits (hydrogen, atom, MIRV) pulled down 6–8dB;
previously-quiet hits (sam-hit, message) brought up to match
- Short clips (`click.mp3`, `ka-ching.mp3`) too short for EBU R128 — got
a flat -6dB trim
## Why
Addresses #3728, specifically the "*WAY too loud*" feedback. Loudest
clips were peaking within ~1.5dB of clipping.
Does **not** change overlap/stacking — per discussion in #3728 and
#3394, the 8-concurrent-sound channel limit is retained intentionally.
At -22 LUFS, multiple overlapping events remain comfortable.
## Before / after (key files)
| Effect | Before (LUFS / TP dBFS) | After (LUFS / TP dBFS) | Δ |
|---|---|---|---|
| hydrogen-hit | -14.94 / -1.62 | -22.52 / -9.10 | −7.6 dB |
| atom-launch | -17.16 / -1.53 | -23.84 / -8.14 | −6.7 dB |
| hydrogen-launch | -16.15 / -1.92 | -23.65 / -9.37 | −7.5 dB |
| mirv-launch | -19.08 / -3.17 | -24.80 / -9.80 | −5.7 dB |
| sam-hit | -34.56 / -10.77 | -23.97 / -1.98 | +10.6 dB (raised up) |
| message | -29.47 / -24.46 | -21.97 / -17.00 | +7.5 dB (raised up) |
All durations unchanged (verified with `ffprobe`). All true peaks stay
below -1 dBFS — no clipping.
## How
Applied with ffmpeg's EBU R128 `loudnorm` filter:
```
ffmpeg -i in.mp3 -af "loudnorm=I=-22:TP=-2:LRA=7" -codec:a libmp3lame -q:a 2 out.mp3
```
Files shorter than the 1-second EBU R128 window (`click.mp3` 153ms,
`ka-ching.mp3` 586ms) used \`-af volume=-6dB\` instead.
## Test plan
- [x] Singleplayer: launch atom / hydrogen / MIRV nukes, verify
detonations are satisfying but not startling
- [x] Build city / port / warship / SAM, verify construction sounds sit
naturally in the mix
- [x] Trigger alliance suggest/break, verify they match loudness of
build sounds
- [x] Trigger many simultaneous events, verify the mix is comfortable
- [x] Verify no audio truncation / glitching / clipping
Addresses #3728
## Description:
Building off of [this
PR](https://github.com/openfrontio/OpenFrontIO/pull/2090) which
implemented music, I extend this functionality to add sound effects.
Diff will be reduced if and when that PR gets merged!
I think the game would benefit from more sound effects, and adding a
"ka-ching" sound effect on kill seems like an easy place to start.
The ka-ching sound effect was found
[here](https://freesound.org/people/AKkingStudio/sounds/684165/) and is
licensed under Creative Commons.
## Please complete the following:
- [x] I have added screenshots for all UI updates
- [x] I process any text displayed to the user through translateText()
and I've added it to the en.json file
- [x] I have added relevant tests to the test directory
- [x] I confirm I have thoroughly tested these changes and take full
responsibility for any bugs introduced
Demo video with sound:
https://github.com/user-attachments/assets/18c857a4-a741-492a-bbc1-68d4f3ba38da
## Please put your Discord username so you can be contacted if a bug or
regression is found:
basedgob
---------
Co-authored-by: icslucas <carolinacarazolli@gmail.com>
Cameron Clark