Creating Sound Effects (SFX) for Mobile Games
Sound effect lives 0.1–2 seconds. In that time it must confirm player action, convey object physical properties, and not annoy at hundredth repeat. This is harder than seems.
Why One File Per Event is Wrong
If wooden floor footstep — one WAV file, brain notices repeating after 8–10 steps. This "machine gun effect" — game audio term. Solution — variation pool: 4–6 sound variants with slight differences in pitch (±2 semitones), volume (±2 dB), timing. In Unity AudioSource.pitch = Random.Range(0.95f, 1.05f). In Wwise — Random Container with shuffle mode.
Second variation level — context variants: metal footstep sounds different than stone. Requires surface detection system: raycast under character feet returns PhysicsMaterial, by which right pool selected.
How SFX Created
Synthesis. For UI sounds, sci-fi effects, magic — synthesizers (Serum, Vital) and FM synthesis (FM8, DX7 emulation). Arcade game explosion — this layering: low-end boom (sub via sine or pitchdown), transient (white noise through band-pass), tail (reverb with decay 0.8–1.2 s). All three synthesized or processed independently, then mixed.
Foley. Organic sounds — steps, hits, creaks — often recorded in studio. RPG fist hit: real punch into leather bag + thin wooden crack + synthetic transient in high-mid (2–4 kHz for "bite"). Layering in DAW (Reaper, Pro Tools, Nuendo), processing: EQ for body shape, compression with fast attack for transient emphasis, saturation for density.
Libraries. Sonniss GDC Bundle (free, thousands sounds), Boom Library, A Sound Effect — source material, refined for project. Taking "out of the box" without processing — bad practice: sound recognizable (heard in 20 other games) and won't fit overall palette.
Technical Requirements for Mobile Platforms
Final files: WAV, 44.1 kHz, 16 bit for most effects. Music stings and ambient — 48 kHz / 24 bit. Stereo only for effects used in 3D positioning or music loops. Short UI sounds — mono, half memory.
Unity transcodes WAV to Vorbis (Android) and AAC (iOS) on build. For very short sounds (< 200 ms) — use Decompress On Load + PCM, else decompression adds latency. For long ambient tracks — Compressed In Memory.
Normalization to -16 LUFS (integrated) before delivery — mandatory. Peak limit — -1 dBTP. Without this mix on device uncontrollable.
What We Deliver
All SFX — named WAV files with description in specification. If project on Wwise or FMOD — additionally configured events with variations inside middleware. If Unity — prefab AudioClip with import settings or AudioMixer group.
1–2 weeks for standard set of 30–80 effects. Cost depends on volume and complexity — calculated after sound map.