MatterMRI — Test panel
Scan: 9DE44C40-E773-4731-943E-6289D54FF88B
Created: 2026-10-03T14:00:47Z
Device: iPhone, iOS 27.0.1
Readings: 10/10 · Surface evidence ready
Grid: 3 × 3, manually marked spacing 20.0 cm; origin A1, columns right, rows down. No measured camera/depth geometry.
Notes: Not provided

Reference · manually chosen reference contact
  Background: -62.68 dBFS; chirp: -51.47 dBFS; tap window: -61.05 dBFS
  Quiet magnetic magnitude: 134.48 µT; motion RMS: 0.00 g
  Reference for comparisons
  
  Structure: unknown. Input: MicrophoneBuiltIn:Built-In Microphone; output: Speaker:Speaker; 48000.0 Hz; system volume: 0.6500000357627869

A1 · x=0.0 cm, y=0.0 cm
  Background: -60.12 dBFS; chirp: -47.19 dBFS; tap window: -58.47 dBFS
  Quiet magnetic magnitude: 133.89 µT; motion RMS: 0.00 g
  Change from reference · chirp: +4.28 dB; tap window: +2.58 dB; magnetic: -0.60 µT
  
  Structure: unknown. Input: MicrophoneBuiltIn:Built-In Microphone; output: Speaker:Speaker; 48000.0 Hz; system volume: 0.6500000357627869

A2 · x=20.0 cm, y=0.0 cm
  Background: -62.31 dBFS; chirp: -47.16 dBFS; tap window: -61.68 dBFS
  Quiet magnetic magnitude: 150.64 µT; motion RMS: 0.00 g
  Change from reference · chirp: +4.30 dB; tap window: -0.63 dB; magnetic: +16.16 µT
  
  Structure: unknown. Input: MicrophoneBuiltIn:Built-In Microphone; output: Speaker:Speaker; 48000.0 Hz; system volume: 0.6500000357627869

A3 · x=40.0 cm, y=0.0 cm
  Background: -57.75 dBFS; chirp: -42.09 dBFS; tap window: -62.87 dBFS
  Quiet magnetic magnitude: 137.87 µT; motion RMS: 0.01 g
  Change from reference · chirp: +9.38 dB; tap window: -1.82 dB; magnetic: +3.39 µT
  
  Structure: unknown. Input: MicrophoneBuiltIn:Built-In Microphone; output: Speaker:Speaker; 48000.0 Hz; system volume: 0.6500000357627869

B1 · x=0.0 cm, y=20.0 cm
  Background: -63.90 dBFS; chirp: -49.85 dBFS; tap window: -63.41 dBFS
  Quiet magnetic magnitude: 132.60 µT; motion RMS: 0.00 g
  Change from reference · chirp: +1.61 dB; tap window: -2.36 dB; magnetic: -1.89 µT
  
  Structure: unknown. Input: MicrophoneBuiltIn:Built-In Microphone; output: Speaker:Speaker; 48000.0 Hz; system volume: 0.6500000357627869

B2 · x=20.0 cm, y=20.0 cm
  Background: -64.54 dBFS; chirp: -49.97 dBFS; tap window: -60.58 dBFS
  Quiet magnetic magnitude: 139.76 µT; motion RMS: 0.00 g
  Change from reference · chirp: +1.49 dB; tap window: +0.47 dB; magnetic: +5.28 µT
  
  Structure: unknown. Input: MicrophoneBuiltIn:Built-In Microphone; output: Speaker:Speaker; 48000.0 Hz; system volume: 0.6500000357627869

B3 · x=40.0 cm, y=20.0 cm
  Background: -50.00 dBFS; chirp: -52.28 dBFS; tap window: -65.47 dBFS
  Quiet magnetic magnitude: 129.80 µT; motion RMS: 0.00 g
  Change from reference · chirp: -0.81 dB; tap window: -4.42 dB; magnetic: -4.69 µT
  
  Structure: unknown. Input: MicrophoneBuiltIn:Built-In Microphone; output: Speaker:Speaker; 48000.0 Hz; system volume: 0.6500000357627869

C1 · x=0.0 cm, y=40.0 cm
  Background: -56.99 dBFS; chirp: -47.99 dBFS; tap window: -64.16 dBFS
  Quiet magnetic magnitude: 131.41 µT; motion RMS: 0.00 g
  Change from reference · chirp: +3.47 dB; tap window: -3.11 dB; magnetic: -3.08 µT
  
  Structure: unknown. Input: MicrophoneBuiltIn:Built-In Microphone; output: Speaker:Speaker; 48000.0 Hz; system volume: 0.6500000357627869

C2 · x=20.0 cm, y=40.0 cm
  Background: -64.13 dBFS; chirp: -47.81 dBFS; tap window: -63.42 dBFS
  Quiet magnetic magnitude: 131.45 µT; motion RMS: 0.00 g
  Change from reference · chirp: +3.66 dB; tap window: -2.38 dB; magnetic: -3.04 µT
  
  Structure: unknown. Input: MicrophoneBuiltIn:Built-In Microphone; output: Speaker:Speaker; 48000.0 Hz; system volume: 0.6500000357627869

C3 · x=40.0 cm, y=40.0 cm
  Background: -64.47 dBFS; chirp: -47.64 dBFS; tap window: -60.00 dBFS
  Quiet magnetic magnitude: 130.95 µT; motion RMS: 0.00 g
  Change from reference · chirp: +3.83 dB; tap window: +1.05 dB; magnetic: -3.53 µT
  
  Structure: unknown. Input: MicrophoneBuiltIn:Built-In Microphone; output: Speaker:Speaker; 48000.0 Hz; system volume: 0.6500000357627869

Method v1: eight-second mono PCM recordings with approximately 10 Hz audio power metering; quiet background, a two-second linear speaker sweep (300–4000 Hz, amplitude 0.15), then three manually performed taps cued at 4, 5.5 and 7 seconds. The actual chirp start offset is saved per reading. Acoustic summaries average linear power before conversion to dBFS, not calibrated sound pressure. The tap-window mean includes ambient sound and is not a tap count or resonance estimate. Accelerometer and gyroscope request 25 Hz, magnetometer requests 20 Hz. Motion RMS removes the mean acceleration vector; handling remains. Magnetic comparison uses the median raw field magnitude only before speaker playback; these readings are uncalibrated. Missing sensors remain unavailable. Clipping and changed input, output, sample rate or volume exclude a comparison.

This proof of concept collects surface evidence. It does not identify studs, voids, metal or pipes, estimate depth, or provide confidence probabilities. All hidden structure remains unknown. Speaker-to-microphone coupling, ambient noise, phone magnets, cases, contact pressure, orientation and inconsistent taps affect results. Use a known test panel to assess repeatability. No inverse solver, AI diagnosis, camera/LiDAR reconstruction or opposite-side phone is implemented.
Original recordings and timestamped audio/motion/gyro/magnetic samples accompany this report. Nothing is uploaded automatically.