Guitar Resonance Frequency Finder
Discover your guitar's body resonance frequency with a simple body resonance test. Tap the guitar body near the bridge, and this tool identifies the dominant resonance peak, finds problematic wolf notes, compares the reading against known body types, and tracks changes after setup adjustments — all processed locally in your browser.
Guitar Resonance Finder Tool
How to Use the Guitar Resonance Frequency Finder
1. Set Up Your Microphone
Select your preferred microphone from the dropdown. A condenser mic or your laptop's built-in mic works well. Position it 5–15 cm from the guitar's soundhole for best results.
2. Click "Start Listening"
Grant microphone permission when prompted. The spectrum display will begin showing real-time frequency content. You can also press Space to start.
3. Tap the Guitar Body
With the strings muted (use your fretting hand), tap the guitar body near the bridge with your knuckle or fingernail. The tap excites the body's natural resonance — also called the tap tone or soundboard resonance — which the tool detects as the strongest peak in the 50–500 Hz range. The tap tone response reflects the combined effect of top stiffness, bracing stiffness, wood mass, and internal air volume.
4. Read Your Results
The large frequency display shows your guitar's detected resonance frequency and its closest musical note. The Wolf Notes panel shows which fretted notes might be problematic due to proximity to the body resonance. The Body Type Comparison cards indicate how your guitar compares to typical body shapes — for example, a typical dreadnought resonance sits around 160–200 Hz, while classical guitar resonance tends to peak nearer 180–220 Hz. You can verify pitch accuracy independently using the guitar note identifier, which identifies played notes by pitch rather than by tap excitation.
5. Before/After Comparison
Click Capture Baseline to save the current spectrum. Make an adjustment (string change, bridge modification, bracing tweak, or nut/saddle swap), then click Capture After. The tool overlays both spectra and highlights the difference. This is particularly useful for luthiers voicing a top — repeated tapping with thin bracing versus heavy bracing shows the shift in the resonance peak directly. Changing from light-gauge to medium-gauge strings typically raises body tension and shifts the resonance peak upward by a few hertz.
6. Export Your Data
Use Copy to copy the resonance reading to your clipboard, or Export CSV to download the full spectrum data for further analysis in a spreadsheet. To explore the full frequency content of a played note — including its harmonic partials — you can follow up with the fundamental frequency finder, which performs advanced F0 detection and harmonic analysis on sustained tones.
Frequently Asked Questions
What is guitar body resonance?
Guitar body resonance (also called the "main air resonance" or Helmholtz resonance) is the frequency at which the guitar body vibrates most efficiently. It is primarily determined by the size and shape of the body, the stiffness of the top and back, and the size of the soundhole. When you tap the body, this resonance frequency is excited more strongly than other frequencies, producing a clear peak in the spectrum.
What are wolf notes and why do they matter?
Wolf notes occur when a played note's fundamental frequency is very close to the guitar's body resonance. The body and string "compete" for energy, causing uneven sustain, beating, or a pulsating volume effect. Notes within roughly ±2 semitones of the body resonance are most susceptible. Knowing where your wolf notes are helps you adjust your playing technique or make setup modifications to minimize the effect.
How should I tap the guitar for the best reading?
Mute all strings with your fretting hand so they don't vibrate. Then tap the guitar top (soundboard) near the bridge with your knuckle or fingertip — a firm but controlled tap. The area near the bridge excites the body's resonance most effectively. Repeat the tap 3–5 times and observe the average reading for consistency.
Why does my guitar's resonance not match any body type exactly?
The body type reference values are typical averages. Every guitar is unique — the wood species, bracing pattern, top thickness, finish, humidity, and even string tension all influence the resonance frequency. A difference of 10–20 Hz from the listed value is perfectly normal. The comparison is a guideline, not an absolute classification.
Can I use this tool with electric guitars?
Solid-body electric guitars have minimal acoustic body resonance (typically very low amplitude and broadly spread). This tool is designed primarily for acoustic and semi-hollow body guitars where the body acts as a significant resonator. On a semi-hollow (e.g., ES-335 style), you may detect a resonance peak, though it will usually be weaker than on a full acoustic.
Is my audio data safe? Is anything uploaded?
Your audio is 100% private. All frequency detection, analysis, and visualization happens entirely in your browser using the Web Audio API. No audio data is ever recorded, stored, or transmitted to any server. The tool works completely offline once loaded.
Does humidity or temperature affect guitar body resonance frequency?
Yes — both factors matter. Wood stiffness increases slightly at lower humidity as the top dries out and loses mass, which tends to raise the resonance frequency by a small amount (often 5–15 Hz between seasonal extremes). High humidity causes the top to swell and soften, lowering the peak. Temperature has a secondary effect through its influence on wood elasticity. For consistent before/after comparisons, try to measure under the same environmental conditions.
What does the "Consistency" stat mean, and how high should it be?
Consistency measures how tightly your repeated tap-test peaks cluster together. A value above 90% means successive taps produce nearly the same resonance peak, which indicates a clean, unambiguous Helmholtz resonance. Values below 70% often mean the strings were not fully muted, background noise is interfering, or the tap force varied greatly. Aim for at least 3–5 taps with consistent results before relying on the reading for a setup decision.
Can I use this tool to check changes after a string gauge change?
Yes, the Before/After Comparison is well-suited to this. Capture a baseline with your current strings installed (muted), swap string gauges, retune, then mute and tap again for the "After" capture. Heavier-gauge strings increase neck tension and alter top deflection, which typically shifts the body air resonance by a few hertz and may also broaden or sharpen the resonance peak. The spectral overlay makes these subtle acoustic changes visible rather than relying on subjective listening alone.
How does this differ from a professional luthier's tap-tone analysis?
Professional tap-tone analysis uses calibrated accelerometers or laser vibrometers to map the full mode shapes of the top (Chladni patterns), measuring Helmholtz, main top, and main back resonances separately. This browser tool detects only the dominant resonance peak captured by a microphone, which is usually the Helmholtz (air) resonance. It is a practical, accessible reference — useful for tracking relative changes and identifying wolf-note regions — but it does not replace a full acoustic guitar modal analysis in a controlled environment.
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