Audio Wavelength & Period Calculator
Calculate the wavelength, half-wave, quarter-wave dimensions, and period for any audio frequency at a given air temperature. Critical for speaker placement and room acoustics.
Results
What is it?
Every sound frequency has a corresponding physical wavelength determined by the speed of sound divided by frequency (? = c/f). Speed of sound in air increases with temperature: approximately 343 m/s at 20�C. Understanding wavelengths is essential for loudspeaker directivity, room mode prediction, absorption panel thickness, and port tube design.
How to use
Enter the frequency you want to analyze and the ambient temperature. Results include the full wavelength, half wavelength, quarter wavelength (useful for pipe/port resonator design), and the signal period. The quarter wavelength is the minimum depth needed for an effective absorption panel at that frequency.
Example scenario
A home studio designer wants to treat a 125 Hz room mode. Quarter wavelength at 125 Hz = 343.2/(4 � 125) = 68.6 cm (27"). This means acoustic panels need to be at least 27cm (roughly 10.5") thick to provide meaningful absorption at 125 Hz � why most broadband bass traps are 4�12" thick rockwool with an air gap.
Pro tip
Above 1 kHz, wavelengths become shorter than typical speaker driver dimensions, causing beaming (narrow directivity). A 1 kHz signal has a 34.3 cm wavelength � speakers with cones wider than ~11 cm (half wavelength) start to beam above 1 kHz. This is why tweeter/midrange crossovers are typically set in the 1.5�5 kHz range and why line arrays are used for long-throw applications.