๐ต Beat Frequency Calculator
The difference between the two frequencies is the beat frequency.
Enter the frequencies of two tones to calculate the frequency of the "beats" produced by their difference. When two tones with slightly different frequencies sound together, the volume periodically swells and fades โ a phenomenon called beating. It's a handy way to gauge how close an instrument is to a reference pitch.
How to use
- Enter the frequency of the first tone (Hz).
- Enter the frequency of the second tone (Hz).
- The beat frequency is calculated automatically.
How the calculation works
When two sounds with slightly different frequencies play together, the volume swells and fades in a regular pulse, called beating. This tool calculates how fast the beats are from the two frequencies. Beat frequency (beats per second) = |frequency 1 โ frequency 2| The two waves reinforce each other when they line up and cancel when they are opposite, producing as many swells per second as the difference in hertz.
Worked example
440 Hz and 444 Hz โ 4 beats per second 440 Hz and 441 Hz โ 1 beat per second (a slow wobble) 440 Hz and 440 Hz โ no beats (perfectly in tune) When tuning a guitar, play the 5th string at the 5th fret together with the open 4th string and turn the peg in the direction that slows the beats until they stop.
Things to be aware of
- Above about 10 beats per second, beating stops sounding like a wobble and becomes a rough, muddy sound.
- Piano tuners count the beat rates of equal-tempered intervals to set the tuning.
- Beats are easiest to hear when the difference is only a few hertz.
FAQ
What is a beat frequency?
When two tones with slightly different frequencies sound together, the volume rises and falls at a rate equal to the difference between their frequencies. Physically, it results from the superposition of two sine waves.
What's the formula?
The beat frequency equals the absolute difference between the two frequencies: |f1 - f2|.
How is this useful for tuning instruments?
Play a reference tone alongside your instrument's tone at the same time โ the slower the beating, the closer the two frequencies are. When the beating disappears entirely, the frequencies match and the instrument is in tune.