Tools
Acoustic Simulation
Interactive 2D wave physics sandbox
Fletcher-Munson Curves
Equal-loudness contours visualization
QRD Designer
Design Schroeder diffusers (QRD, PRD, PRN) with 2D and 3D views
Room Mode Simulator
Visualize axial, tangential, and oblique modes; check Bolt/Bonello ratios; place speakers
Wave Types
Compare transverse and longitudinal wave motion
Study Session
Combine multiple topics into one practice session
Live Classroom
Host a shared topic session with room codes, live rounds, and class stats
Introduction to Sound
The Decibel
Intro to the Decibel
Logarithms, dB formulas for power and pressure ratios, and dB relationships.
The dB & Units
dBSPL, dBu, dBV, dBFS, and reference levels.
Adding dB
Combining sound levels, coherent vs incoherent addition, and power summing.
Sound at a Distance
Inverse square law, free field, near/far field, air absorption, and SPL drop-off.
The Ear & Psychoacoustics
The Ear
Outer, middle, and inner ear anatomy, and how hearing works.
Equal Loudness Curves
Fletcher-Munson curves, phons, loudness perception across frequency.
Weighted dB & Ear Safety
A-weighting, C-weighting, exposure limits, and hearing protection.
Interaural Cues
ITD, ILD, head shadow, and how the brain localizes sound.
The Precedence Effect
Haas effect, fusion zone, echo threshold, and localization dominance.
Wave Concepts
Sound Movement
Reflection, transmission, and how sound behaves at boundaries.
Diffraction
How sound bends around obstacles and through openings.
Refraction
How sound bends due to speed changes in the medium.
Diffusion
Scattering sound energy, diffuser types, and room treatment.
Absorption
Absorption coefficients, materials, porous vs resonant absorbers.
Standing Waves & Room Modes
Nodes, antinodes, axial/tangential/oblique modes, and room resonance.