// Acoustic calculator

Horn
Sizing

Pick a target frequency and get the dimensions you need for a round mouth horn. Length = λ/2, mouth area = (λ/2)².

Frequency Hz
20 80 320 1.3k 5.1k 20k
// Results Round mouth
Wavelength 429 cm ≈ 4.29 m
Horn Length 214 cm ≈ 2.14 m
Mouth Diameter 242 cm ≈ 2.42 m
Mouth Area 45,957 cm² ≈ 4.60 m²

// Assumptions

Speed of sound: 343 m/s (dry air, ~20 °C). Assumes a round mouth. Horn length is the acoustic path from throat to mouth. Actual dimensions also depend on throat size and expansion ratio — treat these as practical targets, not exact values.

// Rectangular mouths

  • —Sizing: use W × H ≥ (λ/2)² instead of mouth area.
  • —Loading: the smaller dimension limits low-frequency loading, not the area.
  • —Directivity: horizontal and vertical dispersion differ — wider mouth narrows horizontal coverage.
  • —Diffraction: sharp corners add coloration; rounding them helps.