# Contact Zero sound effects

Game effects selected from [効果音ラボ](https://soundeffect-lab.info/), acquired **2026-10-04 UTC**. Ten short mono MP3 extracts from eight recordings total **49,964 bytes**. Only game assets are shipped; original long recordings, candidate collections and QA recordings are excluded.

| Official sound / source page                                                           | Game event                                 | Local files / bytes                                                 | Extract                 |
| -------------------------------------------------------------------------------------- | ------------------------------------------ | ------------------------------------------------------------------- | ----------------------- |
| [サブマシンガン発射1](https://soundeffect-lab.info/sound/battle/battle2.html)          | Rifle / carbine muzzle, one cue per bullet | `selab-auto-shot.mp3` / 2,238                                       | 0.00–0.12s              |
| [狙撃銃発射](https://soundeffect-lab.info/sound/battle/battle2.html)                   | Precision rifle muzzle                     | `selab-precision-shot.mp3` / 7,567                                  | 0.00–0.55s              |
| [サブマシンガンの弾倉をセット](https://soundeffect-lab.info/sound/battle/battle2.html) | Manual / squad reload start                | `selab-reload.mp3` / 3,805                                          | 0.18–0.44s              |
| [アスファルトの上を歩く1](https://soundeffect-lab.info/sound/various/)                 | Hard surface contact, alternating steps    | `selab-step-asphalt-1.mp3`, `selab-step-asphalt-2.mp3` / 2,865 each | 0.00–0.18s / 0.66–0.84s |
| [芝生の上を歩く](https://soundeffect-lab.info/sound/various/)                          | Grass / hedge contact, alternating steps   | `selab-step-grass-1.mp3`, `selab-step-grass-2.mp3` / 3,178 each     | 0.00–0.20s / 0.60–0.80s |
| [爆発2](https://soundeffect-lab.info/sound/battle/battle2.html)                        | Grenade / proximity explosion at impact    | `selab-explosion.mp3` / 10,388                                      | 0.00–0.80s              |
| [自動ドアが開く](https://soundeffect-lab.info/sound/various/)                          | Base sliding door opening / closing        | `selab-door.mp3` / 4,432                                            | 0.13–0.43s              |
| [宇宙基地サイレン](https://soundeffect-lab.info/sound/battle/battle2.html)             | One short cue when a WAVE begins           | `selab-wave-alarm.mp3` / 9,448                                      | 0.09–0.81s              |

Selection is provisional: official descriptions and decoded waveform onsets informed the choices; **subjective listening is unverified**. Automatic fire uses a single onset trimmed to 120ms for the game's 140ms bullet spacing. Carbine plays it at 1.1×; precision rifle uses its own recording at 0.94×. Each extract uses 44.1kHz mono, 96kbps MP3, 3ms attack and 15ms release fades. `catalog.json` records download origins, original/processed hashes, sizes, source slices, events and acquisition date.

## Use conditions

The [official agreement](https://soundeffect-lab.info/agreement/) and [FAQ](https://soundeffect-lab.info/faq/) were checked on 2026-10-04. Downloading constitutes agreement to the terms. Personal and commercial use is free; credit is optional, and copyright remains with 効果音ラボ. These recordings are **not CC0 or CC BY**. Use here is limited to effects embedded in Contact Zero gameplay, supported by the published app/game examples. Runtime loads local game assets rather than hotlinking to their server.

Do not redistribute these files (including modified extracts) as materials, create a sample player or effect-only showcase, hotlink to audio, or use them for AI training. The agreement also prohibits adult/illegal/public-order-violating uses and actions restricting others' use, such as Content ID or audio trademark registration. Do not treat this repository as an audio asset library. Repository visibility and public deployment are unchanged by this work.

## Retained sources and playback

`laserSmall_000.ogg` remains the alien energy shot: [Kenney — Sci-Fi Sounds](https://kenney.nl/assets/sci-fi-sounds), [CC0 1.0](https://creativecommons.org/publicdomain/zero/1.0/). `humanDeath1.wav` and `zombieDeath1.wav` remain actual death cues: [ArcadeParty — Zombie / Skeleton / Monster Voice Effects](https://opengameart.org/content/zombie-skeleton-monster-voice-effects), CC0 1.0. Original bytes and credits are preserved. Replaced AVW gun / Kenney footstep / explosion assets are removed. Historical source/license text remains in `licenses/`; it does not change 効果音ラボ's terms.

Master volume defaults to 25%; mute and volume persist independently of campaign saves. Browser gestures unlock audio, unique files preload once, and failures never block gameplay. Peak normalization and a maximum of four voices bound simultaneous output below 0.8 full scale at master 100%. Footsteps are quieter, coalesce within 60ms and use at most two voices; reload uses at most two; a live door or WAVE cue does not stack. Explosions and deaths preempt low-priority footsteps. Crawling stays silent. Hidden/stale/consumed cues are discarded; loading/resetting clears transient queues. Door/WAVE synthesis remains an unavailable-file fallback.

Browser checks verify native MP3 decoding, source scheduling and objective output, including burst/full fire, reload, foot contacts, grenade impact, base doors/WAVE, mute/volume persistence and F5 without historical replay. These checks do not establish perceived quality or speaker loudness. QA evidence stays outside Git.