# Audio credits — Night Signal stage 4

All integrated third-party sounds below are CC0 1.0 and permit modification and redistribution, including commercial demos. Attribution is not required; these credits acknowledge the creators. License: https://creativecommons.org/publicdomain/zero/1.0/ (legal code: https://creativecommons.org/publicdomain/zero/1.0/legalcode).

| Runtime files | Creator / original | Source and license evidence |
| --- | --- | --- |
| rifle.wav, rifle_tail.wav | Ben Jaszczak, Brian Nelson, Kevin Heras, Matthew Nanney — Free Firearm Sound Library, AR-15 D_32P.wav, near recording | https://opengameart.org/content/the-free-firearm-sound-library (CC0; creator statement and attribution) |
| enemy.wav, enemy_tail.wav | Same team, AR-15 D_24P.wav, mid-distance recording | Same source; original archive https://opengameart.org/sites/default/files/Prepared%20SFX%20Library.7z |
| mag_out.wav, mag_in.wav, bolt.wav | SpringySpringo — assaultriflereload1.wav, recorded airsoft handling | https://opengameart.org/content/gun-reload-sounds (CC0); download https://opengameart.org/sites/default/files/assaultriflereload1_0.wav |
| metal.wav, body.wav, step.wav, switch.wav | Kenney — Impact Sounds: impactMetal_medium_000, impactSoft_heavy_000, footstep_concrete_000, impactMetal_light_001 | https://kenney.nl/assets/impact-sounds (CC0); included original License.txt in source/impacts |
| rain.wav | Ylmir — Rain (loopable), Rain OGG.zip / 1.ogg; window rain recording | https://opengameart.org/content/rain-loopable (CC0); https://opengameart.org/sites/default/files/Rain%20OGG.zip |
| engine.wav | monotraum — ship engine.wav; ship engine field recording | https://freesound.org/people/monotraum/sounds/253606/ (CC0); downloaded HQ preview https://cdn.freesound.org/previews/253/253606_1756543-hq.mp3 |
| alarm.wav | TinyWorlds — Storm & Siren; June 2013 German flood siren recording | https://opengameart.org/content/storm-siren (CC0); https://opengameart.org/sites/default/files/storm_3_siren.ogg |
| hull_stress.wav, cargo_shift.wav | blacklodgegames — 27 Metal Audio Samples (SFX); recorded bent/hit metal, wobble_08 and metal_grit_02 | https://opengameart.org/content/27-metal-audio-samples-sfx (CC0); https://opengameart.org/sites/default/files/27-Metal-Audio-Samples-blacklodgegames.com_.zip; original cc0_license.txt retained |
| steam.wav | BEDEEN — Ironer Steam; recorded iron steam | https://freesound.org/people/BEDEEN/sounds/425046/ (CC0); downloaded HQ preview https://cdn.freesound.org/previews/425/425046_8535956-hq.mp3 |

Acquired 2026-09-06. Original downloads and license page snapshots retained under source/ (excluded from Godot import). source/prepare.py and edits.json specify combat trims and mapping: mono 44.1 kHz PCM16, DC removal, short fades and peak normalization. Rifle onset and brief body preserved; optional quiet recorded tail indoors; bounded voices and conservative gains, master limiter. Original stage 3 combat recordings are unchanged. Radio is text with a library click cue, not voiced dialogue.

Stage 4 edit recipe and sample checks: source/stage4/prepare.py and edits.json. Rain (26.5s) and ship engine (21.5s) use 0.5s overlap loops; alarm is a band-limited 9s rising siren excerpt; hull stress is half-speed bent metal with a quiet reflection; cargo shift is slowed metal grit; steam is a 3s excerpt. All six PCM16 mono 44.1 kHz files have zero clipped samples and peaks from -6.94 to -3.74 dBFS before conservative runtime attenuation. File hashes and RMS levels are retained in edits.json. HQ MP3 previews for engine and steam are explicitly retained as the downloaded sources, not represented as original lossless files.

Mission playback uses recorded rain/engine beds, fades room changes, reduces engine presence during scuttling, and ducks ambience 5 dB around fire and warning cues (6 dB for guard windup). Spatial guard alerts reuse the recorded bolt handling at -16 dB with wider spatial reach; radio retains the click. Duplicate first-sight/windup cues on the same guard frame are suppressed. Rifle and enemy tails were lowered 3/2 dB to reduce interior masking and are disabled outdoors, including the stern. Alarm instances cannot stack or be restarted while their recorded rise is playing. The old slice scene's synthesized bed remains only in the legacy test slice.

The tool session can exercise playback, capture the engine mix, inspect spectrum/envelopes and measure peaks, but has no reliable listening input. These checks do not establish sound quality, enemy cue audibility in every room, or comfortable headphone loudness. Human audition of the complete stage 4 mission remains required.