Last Fy / Last Fx
The modal-frequency estimates produced by the most recently accepted impact. They may move from hit to hit.
01 / HOW TO USE
SoundBoard Pro field guide
Your first measurement,
from sample to record.
Follow the same sequence each time: measure the free wooden plate, capture a consistent set of impacts, add the physical data, then interpret and save the result.
No download is required. This guide stays on screen and can be reopened whenever you need it.
THE MEASUREMENT PATH01 — 04
- 01Analyzer↓
- 029 valid impacts↓
- 03Measurement↓
- 04Library
02 / QUICK START
Complete one measurement in eight steps.
The application automates signal analysis, but repeatability still depends on consistent sample dimensions, support, microphone placement, and impacts.
- 01
Identify the two directions
Define the two perpendicular directions of the rectangular free plate before measuring. Keep the same orientation throughout the session: Lx is paired with Fx, and Ly with Fy.
Do not swap x and y between captures. - 02
Measure the sample
Measure Lx, Ly, and thickness h in millimetres with an appropriate measuring tool. Measure mass m in grams with a reliable scale.
Thickness accuracy has a strong effect on the calculated elasticity estimates. - 03
Prepare a quiet, repeatable setup
Allow the plate to vibrate as freely as practical. Avoid pressing a broad area, and keep the support or holding method and the phone position unchanged when comparing samples.
The thesis does not prescribe one fixed phone distance; consistency is more important than inventing a universal distance. - 04
Start the Analyzer
Open Analyzer and tap Start analysis. Grant microphone access when iOS asks. The microphone is active only while analysis is running.
The raw microphone signal is processed on the device and is not saved as an audio recording. - 05
Capture nine valid impacts
Apply controlled, distinct taps to the wooden sample. Watch Valid hits and allow a short pause between taps until the counter reaches 9 / 9.
A harder tap is not automatically a better tap; aim for clear and repeatable impacts. - 06
Move to Measurement
Open Measurement, enter Lx, Ly, h, and m, then use the current analysis values. The dominant Fx and Fy values become the frequency inputs for the calculation.
Dimensions are entered in mm and mass in g. - 07
Review the calculated values
Check density, directional dynamic elasticity estimates Ex and Ey, their ratio, and the specific values. Read them as comparative material information, not as a prediction of a finished instrument.
Capture completeness is not the same as laboratory-certified accuracy. - 08
Name, save, and revisit
Enter a clear record name and save the measurement. Open Library to review the record, export its TXT summary, or delete it.
Records stay on the device until you export or delete them.
03 / READ THE SCREEN
What each value means.
The labels separate the most recent impact, the stable result from the full capture set, and the physical values calculated from the sample.
Dominant Fy / Dominant Fx
Stable modal-frequency values obtained by clustering nearby results across the accepted impacts. Fy is associated with Ly; Fx with Lx.
Live peak
The strongest peak in the current spectrum. It is useful for observing the response but may change quickly.
Dominant live peak
A summary of repeated live peaks. It may lie near Fx or Fy, or show another strong component; it is not the primary elasticity input.
Density ρ
Calculated from mass divided by the volume defined by Lx, Ly, and h. The result is shown in kg/m³.
Ex / Ey
Direction-dependent dynamic modulus of elasticity estimates derived from the free plate’s modal behaviour. They are not direct static mechanical-test values.
Ey / Ex and specific values
Ratios that help compare directional behaviour and stiffness relative to density between samples measured under consistent conditions.
Measurement confidence
Shows progress toward the required nine accepted impacts. It describes capture completeness, not a universal accuracy guarantee.
04 / RELIABLE RESULTS
Make comparisons repeatable.
SoundBoard Pro is most useful when the measuring conditions are controlled and documented.
Keep these consistent
- x/y orientation and sample naming
- support or holding method
- phone position and microphone orientation
- impact point, tool, and approximate strength
- room noise and measurement sequence
- dimension and mass measurement method
Avoid these mistakes
- holding the plate differently between hits
- changing phone distance during the set
- mixing Lx with Fy or Ly with Fx
- entering centimetres instead of millimetres
- treating 9 / 9 as proof of absolute accuracy
- comparing a free plate directly with the finished instrument
!Wood is heterogeneous and anisotropic. Moisture, grain direction, thickness, support conditions, impact point, and the microphone response can all influence the result.
05 / TROUBLESHOOTING
If the measurement does not behave as expected.
01No impact is counted
Confirm that analysis is running and microphone access is enabled. Reduce background noise, produce one distinct controlled tap, and wait briefly before the next tap.
02Fx or Fy changes too much
Keep the support, phone position, and impact method fixed. Reset the hits and repeat the set in a quieter environment.
03Calculated results stay blank
Complete Lx, Ly, h, and m with positive values and confirm that valid dominant Fx and Fy values are available, then use the analysis values again.
04Microphone permission was denied
Open iOS Settings, find SoundBoard Pro, enable Microphone access, and restart the application.
05A saved measurement is missing
Open Library and refresh. Records are local to this device and may be removed when the app is deleted, depending on system backup behaviour.
06 / SCIENTIFIC BASIS
A workshop-oriented preliminary assessment.
The application combines RMS-based impact detection, a Blackman–Harris-windowed FFT, peak selection, and clustering across nine accepted impacts. Density and direction-dependent dynamic elasticity estimates use the modal behaviour of a free rectangular orthotropic plate.
In Çancı’s 2026 master’s study, SoundBoard results for 10 wooden specimens were compared with Chladni patterns and FFT verification screens. The mean absolute difference was approximately 0.58 Hz for Fx and 1.37 Hz for Fy. These findings describe that sample and method; they are not a guarantee for every wood, phone, or environment.
The system is intended to support workshop comparison, documentation, and preliminary material assessment. It does not replace a laboratory measurement system, directly measure damping or acoustic conversion efficiency, or predict the final instrument’s tonal character.
Ready to measure?
Keep this guide open beside SoundBoard Pro for your first few sessions.
