This page is a link to https://tap-a-stick.wood.properties/ – a web app for quickly doing vibration resonance stiffness measurement on wood and similar orthotropic materials. It is designed for doing longitudinal resonance as the primary method for assessment of dynamic modulus of elasticity (Edyn), with flexural modes as confirmation. It can also be used with torsional modes to assess shear modulus. Frequencies being measured need to be well within the normal hearing range as the web app makes use of hardware and software for computer audio. It should work on any computer, smartphone or tablet with a reasonably modern web browser. Please report any bugs to d.ridleyellis@napier.ac.uk.
Tap-a-stick is provided as learning tool with no warranty. Double check its calculations. When measuring, confirm peak frequencies using some other software or equipment (a bug in sample rate could over or underestimate). You can download a wav file to test it here (zip file with info).
The FFT calculations are not done in a way that is suitable for damping measurement (Q-factor is provided to help detection of bad hits).
A help guide will come in time. For now, good luck figuring it out.
Cite as:
Ridley-Ellis, D (2026) Tap-a-stick calculator for impulse excitation technique on wood. Version 1.6. (https://wood.properties/tap-a-stick/) [Web app]
14 June 2026 V1.0 Original version
14 June 2026 V1.1 Added acoustic simulator. Bug fixes and cosmetic improvements.
15 June 2026 V1.2 Added linear y-scale option to FFT. Bug fixes and cosmetic improvements. First reliable version. https://tap-a-stick-v1-2-406567576236.europe-west1.run.app
16 June 2026 V1.3 Added hit detection and reference spectrum features. Sample rate is handled more carefully. Added ZIP upload. Bug fixes and cosmetic improvements. https://tap-a-stick-v1-3-406567576236.europe-west1.run.app
24 June 2026 V1.4 Various improvements to the user interface – including a quick menu and a simplified view. A batch measurement mode has also been added. The underlying calculations are the same and V1.4 should give the same results as V1.3, except that now the hits can also be examined with an FFT of the whole hit duration, which is spline interpolated to 0.1 Hz divisions. This gives more resolution to the calculation of modulus of elasticity. It also allows calculation of Q-factor, but this is to aid detection of bad hits rather than to measure damping per se. Damping measurement requires a very careful set-up and if you really want that you should probably invest in the proper equipment and software. https://tap-a-stick-v1-4-406567576236.europe-west1.run.app
25 June 2026 V1.5 It seemed like it would be useful to have an in-app tool that combined the specimen data across multiple specimen ZIP packages. https://tap-a-stick-v1-5-406567576236.europe-west1.run.app
07 July 2026 V1.6 Has waveform slots and a multizoom tool for more advanced tasks. The theoretical calculation values of E and G can now be changed by dragging the “Longit 1” and “Torsion 1” lines on the fft spectrum. Simple view has a mini-FFT spectrum for a quick confirmation of good peaks. https://tap-a-stick-v1-6-406567576236.europe-west1.run.app
25 July 2026 V.17 Improved the UI for the FFT spectrum and some general styling updates. Now the main FFT graph can be popped out and enlarged and you can navigate by dragging on the canvas with the mouse. https://tap-a-stick-v1-7.ai.studio/