Acoustic wavelength ↔ frequency visual calculator
Enter either frequency or wavelength. Changing either value recalculates the other using the current speed of sound. Lengths can be displayed as feet + inches, decimal feet, inches, metres, centimetres, or millimetres. Feet + inches uses whole feet plus inches rounded to the nearest 1/16 inch.
Wavelength uses the temperature-adjusted speed of sound. Humidity and pressure affect the optional atmospheric absorption model.
Set the distance the wave travels before it reaches the reflecting boundary. The default is five full wavelengths; you can replace it with any real dimension.
Acoustic pressure is drawn as a sinusoidal reference waveform. Hover anywhere in the graph for exact distance, phase, normalized pressure, and relative intensity information.
½ wavelength = 180° of propagation phase. Two coherent, equal-amplitude signals that arrive at the same point 180° apart can cancel completely. Real reflections often differ in level, phase, angle, and spectrum, so real cancellation is usually frequency- and position-dependent.
¼ wavelength is a useful absorber-design reference. A quarter wavelength corresponds to a particle-velocity maximum near a rigid boundary and is commonly used as a first-pass thickness or spacing target for porous absorbers. Actual absorption depends on flow resistivity, material, mounting, incidence angle, air gap, and construction.
Reflection: The reflected line is a simple one-dimensional coherent pressure wave. The default rigid-boundary pressure reflection is non-inverting; the optional 180° mode lets you inspect an inverted boundary condition.
Losses: Atmospheric absorption follows an ISO 9613-1 style pure-tone calculation. Geometric spreading is continuous: pressure approaches 1/r and intensity approaches 1/r² with distance. A smooth 1 m reference radius regularizes the near-source singularity instead of switching spreading on abruptly at 1 m.
Interference: The aggregate curve is the instantaneous algebraic sum of incident and reflected pressure. It is a visualization of phase interaction, not a room-acoustics solver and not a prediction of diffuse-field SPL.