Doppler Effect Calculator (Sound)
Calculate the observed frequency when a sound source or observer moves.
Step-by-step working
- f' = f (c + v_o) / (c − v_s) = 500 × (343 + 0) / (343 − 30)
- = 547.9233 Hz
Mathematical Formula
Overview & Explanation
Approaching sources sound higher; receding ones lower.
How It Works
- Enter speeds with sign.
- Apply the formula.
Practical Applications
- Siren pitch.
- Radar and ultrasound basics.
Example 1: siren 500 Hz approaching at 30 m/s
Higher pitch.
Inputs
Source frequency (Hz): 500 · Observer speed towards source (m/s): 0 · Source speed towards observer (m/s): 30
Step 1
f' = f (c + v_o) / (c − v_s) = 500 × (343 + 0) / (343 − 30)
Step 2
= 547.9233 Hz
Observed frequency
Result
Example 2: same siren receding
Lower pitch.
Inputs
Source frequency (Hz): 500 · Observer speed towards source (m/s): 0 · Source speed towards observer (m/s): -30
Step 1
f' = f (c + v_o) / (c − v_s) = 500 × (343 + 0) / (343 − -30)
Step 2
= 459.7855 Hz
Observed frequency
Result
How it's calculated & sources
f' = f (c + v_o) / (c − v_s); positive speeds mean approaching, negative receding.
Frequently Asked Questions
Light Doppler?
Supersonic source?
Wind?
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