Comb Filter Cancellation Calculator
Where would equal-level direct and delayed copies first cancel, and how far apart are the notches?
Method, formula and assumptions
For two equal-amplitude, same-polarity copies, cancellation frequencies are (k + 1/2) / delaySeconds. Notch spacing is 1 / delaySeconds. Count only positive notches at or below the entered ceiling.
Input definitions and supported units
- Relative delay (ms): Measured or assumed numerical value, from 0.001 to 1000; must be positive.
- Sample rate (Hz): Whole-number count, from 8000 to 384000; must be positive.
- Inspection ceiling (Hz): Measured or assumed numerical value, from 1 to 192000; must be positive.
Worked example with answer
A 2 ms delay produces a first notch at 250 Hz and 500 Hz spacing. Four notches fall at or below 2,000 Hz; the delay equals 96 samples at 48 kHz.
How to use the results
A periodic notch pattern can point toward a duplicated delayed signal. Reducing the delay moves the notches upward, rather than changing them by a constant frequency offset.
Results retain full precision internally and display up to four decimal places. Very small nonzero results use scientific notation rather than appearing as zero. Check the labels before comparing values across units.
Limitations and references
Different levels make shallower notches; polarity inversion swaps peaks and nulls. Real reflections are frequency-dependent, so this is a two-copy model rather than a room response prediction.
The method is a self-contained arithmetic, geometric or explicitly stated mathematical model. There are no imported tariffs, empirical presets or equipment specifications; measured values and allowances must come from your own process.
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Creator & reviewers
Creator persona
- Casey RowanUnits, conversions & measurement
Reviewer personas
- Devon ShawFormula & assumptions review
- Sage MitchellClarity & usability review