Acoustic Impedance Calculator
Calculate specific acoustic impedance and sound reflection/transmission coefficients
Calculate Acoustic Properties
Material Properties
Calculation Results
Specific Acoustic Impedance
Formula Used
z = ρ × c
Where: z = specific acoustic impedance (MRayl), ρ = density (kg/m³), c = speed of sound (m/s)
Example Calculations
Air to Water Interface
Materials: Air (z₁ = 0.0004 MRayl) → Water (z₂ = 1.48 MRayl)
Reflection: R = (0.0004 - 1.48)² / (0.0004 + 1.48)² ≈ 99.9%
Transmission: T = 4 × 0.0004 × 1.48 / (0.0004 + 1.48)² ≈ 0.1%
Application: Why you can't hear sounds underwater clearly
Ultrasound Gel Application
Materials: Skin (z₁ = 1.58 MRayl) → Ultrasound Gel (z₂ = 1.48 MRayl)
Result: Minimal reflection (~0.3%), excellent transmission (~99.7%)
Purpose: Acoustic impedance matching for medical ultrasound
Key Formulas
Units
MRayl (10⁶ Rayleigh) = 10⁶ Pa⋅s/m
Density: kg/m³, g/cm³, lb/ft³
Speed: m/s, ft/s, km/h
Coefficients: dimensionless (0-1)
Common Impedances
Applications
Medical ultrasound imaging
Architectural soundproofing
Non-destructive testing
Underwater acoustics
Audio equipment design
Understanding Acoustic Impedance
What is Acoustic Impedance?
Acoustic impedance (z) is a material property that describes how much a material resists the propagation of sound waves. It depends on both the density of the material and the speed of sound within it.
Key Concepts
- •Higher impedance: More resistance to sound waves
- •Impedance matching: Minimizes reflection
- •Impedance mismatch: Causes reflection
Reflection & Transmission
Conservation Law
Energy Conservation: R + T = 1
Perfect Matching: z₁ = z₂ → R = 0, T = 1
Large Mismatch: z₁ ≫ z₂ → R ≈ 1, T ≈ 0
Medical Applications
Ultrasound Imaging
Gel matches skin impedance for optimal transmission
Lithotripsy
Focused ultrasound for kidney stone treatment
Therapy
Physiotherapy and cancer treatment
Engineering Applications
Non-Destructive Testing
Detecting flaws in materials and structures
Acoustic Design
Room acoustics and noise control
Transducers
Sonar, hydrophones, and acoustic sensors