What this calculator does
Doppler effect (sound) works out observed frequency of a sound source moving relative to a listener. Enter your own figures above and the answer updates as you type: nothing is fixed in the code, so the result reflects exactly the numbers you supply.
The formula this calculator evaluates is printed under the tool and explained below, so you can check the working by hand or reuse it in a spreadsheet.
The formula
Formulaf = f₀(v+v_r)/(v+v_s); v_r positive toward source, v_s positive away from observer
The inputs explained
| Field | What to enter |
|---|---|
| Source frequency (Hz) | A number, measured in Hz. Starts at 440. |
| Speed of sound in the medium (m/s) | A number, measured in m/s. Starts at 343. |
| Observer velocity (+ toward source) (m/s) | A number, measured in m/s. Starts at 0. |
| Source velocity (+ away from observer) (m/s) | A number, measured in m/s. Starts at -20. |
Worked examples
Every figure in the tables below is produced by this page’s own calculator at build time, so the numbers and the tool always agree. Select any row to load that scenario.
How the answer changes with source frequency
Every other input is held at the calculator’s starting values while source frequency varies. Select any row to load that scenario into the calculator.