# 回声与混响 - Echo & Reverberation

使用Web Audio API实时播放音频的交互式回声与混响模拟

> 标准页面: https://elysiatools.com/zh/visualizations/echo-reverberation

- **分类:** Physics

## 概述

Interactive echo and reverberation simulation demonstrating acoustic reflection phenomena with real audio output using Web Audio API. Features comprehensive room acoustic visualization: (1) Room Layout Mode - Top-down room view showing sound source position (S), listener position (L), walls with reflection indicators, adjustable room dimensions (width 5-30m, depth 3-15m, height 3m default), grid overlay with scale markers, and visual representation of sound propagation paths. (2) Sound Ray Tracing - Simplified ray tracing with preset reflection surfaces showing direct sound path (green line) and 8 reflection paths (red dashed lines) from walls, first and second-order reflections, reflection point markers on walls, path length calculation for each reflection, and amplitude decay visualization based on absorption coefficient. (3) Waveform Display - Time-domain visualization showing direct sound pulse followed by delayed reflections, amplitude scaling based on absorption (Aₙ = A₀·(1-α)ⁿ), temporal separation of early reflections (<80ms) and late reflections (>80ms), and RT60 decay window display. (4) Reflection Timeline - Sequential listing of all reflections with arrival time (ms), distance traveled (m), amplitude (%), and reflection order (1st, 2nd, corner), color-coded by reflection type. Adjustable room parameters: room width (5-30m), room depth (3-15m), absorption coefficient α (0-0.95, where 0=fully reflective, 1=fully absorptive), master volume control (0-100%), and sound source/listener positions. Room presets: Small Room (6m×4m, α=0.40 - short reverb, tight sound), Medium Hall (15m×10m, α=0.30 - balanced acoustics), Large Cathedral (25m×15m, α=0.15 - long decay, grand reverb), Outdoor Echo (50m×30m, α=0.05 - distinct slap echo, minimal absorption). Real-time acoustic calculations: Echo delay time t = 2d/v where d=distance to reflecting surface, v=343m/s (sound speed at 20°C), RT60 reverberation time using Sabine formula RT60 = 0.161·V/(A·α) where V=room volume (m³), A=surface area (m²), reflection decay amplitude Aₙ = A₀·(1-α)ⁿ after n reflections, and total reflection count based on room size and absorption. Audio playback implementation using Web Audio API with: Impulse sound generation (hand clap-like percussive sound with noise burst and exponential decay envelope), Direct sound channel with master volume control, Multiple delay nodes for reflections with precise delay times (1-500ms range), Individual gain nodes for each reflection with amplitude scaling, Automatic playback termination after RT60+1s, and simultaneous multi-channel output for realistic spatial effect. Mathematical foundation section covering: Echo Delay Formula t = 2d/v (time for sound to travel distance d and return, doubling accounts for round-trip), RT60 Formula RT60 = 0.161·V/(A·α) (Sabine's equation for reverberation time, V=volume in m³, A=total surface area, α=average absorption coefficient, measures 60dB decay time), Reflection Decay Aₙ = A₀·(1-α)ⁿ (amplitude after n reflections, exponential decay based on absorption), Room Volume V = width×depth×height (total room volume in m³), and speed of sound v = 343m/s at 20°C (temperature dependent: v ≈ 331.3 + 0.606·T where T in °C). Comprehensive educational content: What is Echo & Reverberation? (definitions: echo = distinct repetition of original sound, reverberation = dense cascade of reflections creating 'tail', psychoacoustics: early reflections <80ms integrate with direct sound, late reflections >80ms perceived as echo, Haas effect precedence), How It Works (sound wave propagation in all directions, direct path vs reflected paths, reflection types: specular (smooth surfaces) vs diffuse (rough surfaces), absorption mechanisms: porous absorbers, resonant absorbers, membrane absorbers), Real-World Applications (Concert Hall Design: optimizing RT60 for different music genres - chamber music 1.4-1.7s, orchestral 1.8-2.2s, organ music 2.0-2.5s, Recording Studios: 'dead rooms' with RT60<0.3s for dry recordings, live rooms with RT60>0.6s for ambience, Sonar/Radar: echo ranging for distance measurement d = v·t/2, underwater acoustics, atmospheric sounding, Architectural Acoustics: speech intelligibility requirements RT60<0.8s for classrooms, music enhancement with longer reverb, Audio Production: artificial reverb algorithms (plate, spring, digital), delay effects for creating space, slap echo for rockabilly guitar, hall reverb for orchestral placement), and Listening Guide (listen for distinct 'slap' echo in large reflective spaces, notice decay time - longer = more reverb/wet sound, identify early vs late reflections - early add clarity/width, late create wash/tail, absorption coefficient effect - higher α = shorter decay, room size effect - larger rooms = longer initial delay). Interactive features: Play Echo button triggers impulse sound with all reflections, Stop button terminates audio immediately, Room parameter sliders update calculations in real-time, Preset buttons instantly change room characteristics, Visual waveform shows pulse timing and amplitude relationships, Timeline displays reflection sequence with precise timing, and Room canvas visualizes sound paths and reflection points. Responsive layout with dual-panel design (room visualization left, controls right), waveform section (200px height), reflection timeline (scrollable), formula cards in grid, and applications showcase. Canvas-based rendering with smooth 60fps animations, color-coded paths (green=direct, red=reflected), opacity-based amplitude visualization, and professional acoustic diagram appearance. Multi-language support (zh, en, es, fr, de, ru, pt, ja) with complete translations of interface elements, acoustic terminology, formulas, and educational content.

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