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Process

Ideation & sketches

Design & Fabrication

  • Panels are 15x15cm each
  • Mounted on a metal grid for stability
  • Modular and combinable
  • Different textile techniques
  • Variation in density and thickness
  • Ecru color (white)


Testing

Nearfield testing is a simple method using a calibrated microphone angled at the sample that will help us obtain frequency-resolved α across all octave bands, NRC, T20 decay reduction, AND scattering data. - Absorption α: SPL difference bare vs panel per band (NRC number) - Scattering σ: SPL at multiple angles (standard deviation) - Decay T20: Room decay before vs after placing panel - Reflection shape: Impulse response (clean peak vs diffuse tail)

Table Setup

  • Make sure the table is in the center of the room to avoid sound reflections from walls
  • Mark the center of the table with tape, all samples must be placed at this exact position
  • Use the mic mount so that the UMIK-1 facces down at 10cm above sample. If some samples are thicker, you will need to readjust so that it's always 10cm from the center of the sample (not the table)
  • Lean the speaker at 30–45° facing the sample from the side. I used a stack of books to give it height at 20cm obove the table surface. The distance should be 35cm from the speaker to the center of the sample (diagonal)

Software setup

  • Download REW
  • Download the calibration file (.cal) for the microphone (needs serial number in mic box)
  • Load the calibration file into REW (preferences>microphone>browse)

Soundcard Setup

  • Go to Preferences → Soundcard
  • Set Input device: miniDSP UMIK-1
  • Set Output device: your computer audio output
  • Set Sample rate: 48000 Hz
  • Click Check Levels — snap fingers near the mic to confirm it responds

Measurement Settings

  • Click Measure to open the measurement dialog
  • Set the following parameters:

Type: SPL Start frequency: 200 Hz / End frequency: 10,000 Hz Level: −12 dBFS (increase to −6 or 0 dBFS if the level check reads below −20 dBFS) Method: Sweep Sweep length: 256k Mode: Repeated measurement — set repetitions to 3 Start delay: 0ms / Between measurements: 1000ms Timing: Use acoustic timing reference Output: L+R Input: UMIK-1 — check gain is not clipping (signal should peak between −20 and −6 dBFS during sweep) Check: Play dither before sweep Check: Capture noise floor

Measuring the Bare Table (Reference)

  • Make sure the table is completely bare at the marked centre point — no sample yet
  • Click Start Measuring — REW plays a sine sweep automatically, wait for it to finish
  • Repeat 3 times, naming each: BARE_TABLE_01, BARE_TABLE_02, BARE_TABLE_03
  • To average: go to Overlays → select all 3 → click Average the Responses (bottom left) > rename result: BARE_TABLE_avg
  • Save: File>Save All Measurements

Measuring Each Sample

  • Place sample flat on the tape mark, measurement face up
  • Adjust mic height so it is exactly 10cm above the sample surface
  • Click Start Measuring: run 3 sweeps, average them, name the result using the sample ID (e.g. ABS-01_avg)
  • Remove sample, place next one. Do not move the speaker or mic between samples
  • If you accidentally knock the mic or speaker, re-run the bare table baseline before continuing
  • Save after each sample: File>Save All Measurements
  • Note: REW free version has a 30 measurement limit. Average each sample's 3 sweeps and delete the individual sweeps as you go to save space

For the Air Gap Test

  • Repeat the exact same process above
  • Place small spacers (coins, bottle caps, or cut cardboard) under the four corners of each sample to create a 4cm gap between the sample bottom and the table
  • The bare table reference remains the same. Do not re-measure it
  • Include a fresh bare table measurement at the start of the gap session for the most accurate reference
  • Name samples with the gap suffix: e.g. ABS-01_gap_avg

Exporting Data

  • When all samples are measured: go to Overlays window
  • File>Export>Export all measurements as text
  • Settings: use one file for all measurements, delimiter: Tab, units: SPL
  • This exports a .txt file with SPL values at every frequency for every sample
  • Use this file to calculate α, NRC, and compare results

Testing results file

Tools

- [EQ Wizard](https://www.roomeqwizard.com/)
- [UMIK-1 Calibrated Microphone](https://www.minidsp.com/products/acoustic-measurement/umik-1?srsltid=AfmBOor7Ar_iqsGDmsUNt4tmfisn6eMPfQOfZM6CvBTYK2nSBkkWKoVh)
- computer + speaker
- 15×15cm panels to test
- flat table (hard surface)
- speaker 
- mic stand
- tape to mark exact positions

Fabrication files

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