How to use repeatable test tones without overclaiming accuracy
Use SignalProof as a controlled signal source while keeping acoustic sound pressure claims tied to what the measurement setup can actually prove.
Before you start
Keep system volume fixed.
Write down position and conditions.
Start quietly; confirm the output route.
Treat results as practical comparisons.
SignalProof is useful when the signal side of an audio test needs to stay consistent.
It can generate a sine tone, noise profile, or sweep with known digital parameters. That makes it easier to compare what a meter reads across devices, distances, rooms, or before-and-after conditions.
The useful question is not “does this phone create a certified sound pressure level?” It is “did I repeat the same signal and document enough of the setup to understand the comparison?”
What SignalProof controls
- signal type, such as sine, pink noise, white noise, brown noise, or sweep
- digital output level in dBFS
- frequency or sweep range
- channel selection
- playback state and local test notes
dBFS is not dBSPL
SignalProof's level control is expressed in dBFS, a digital level relative to the maximum representable digital signal. A sound meter reports an acoustic result such as dBSPL after the signal passes through the iPhone volume setting, output route, speaker, air, room, distance, and meter.
Keeping dBFS fixed is useful because it removes one changing variable. It does not convert that digital setting into a guaranteed acoustic level.
What it cannot guarantee
SignalProof cannot promise a fixed acoustic dBSPL value in the room. The measured sound pressure depends on the iPhone model, system volume, speaker behavior, distance, reflections, background noise, and the meter being used.
That is why SignalProof should be treated as a repeatable signal source, not as a certified sound level calibrator.
A safer basic workflow
- Set a conservative output level.
- Keep the iPhone volume, distance, and room conditions consistent.
- Measure with an external meter or a meter app such as SilentProof on a second device. SignalProof supplies the test signal.
- Save the test context, not just the number.
Use the saved setup to repeat the check and interpret the difference.
A repeatability worksheet
Record this information for every run:
| Field | What to write down |
|---|---|
| Signal | Sine frequency, noise type, or sweep range |
| SignalProof level | The displayed dBFS setting |
| Channel | Left, right, or stereo |
| Playback timing | Continuous, timed, burst, or intermittent when available |
| iPhone | Model, iOS version, and system volume |
| Output | Built-in speaker, wired route, Bluetooth route, or external system |
| Geometry | Source position, meter position, orientation, and distance |
| Room state | Doors, windows, HVAC, curtains, furniture, and people |
| Meter | Device or app, weighting, time setting, and displayed result |
Saving only the final number removes the information needed to reproduce it. The setup record is part of the result.
Check repeatability before comparing changes
Run the same setup twice before introducing the change you want to evaluate. If those two baseline readings do not agree closely enough for your purpose, troubleshoot the setup first:
- Confirm that system volume and the output route did not change.
- Restore the source and meter to the marked positions.
- Check for background-noise or room-state changes.
- Confirm the same SignalProof preset or parameters.
- Repeat the baseline before evaluating the new device, room position, door, or window condition.
This baseline step prevents normal setup variation from being mistaken for an improvement or defect.