01
Measure live
Monitor LAF, LAS, LAI, LAeq, LCpeak, time history and live frequency behaviour while the app tracks overload, clipping, paused intervals and signal-validity conditions.
SPL Reference
Professional sound measurement for iPhone
Measure sound. Verify the measurement.
DSR SPL Reference is a professional iPhone sound-level and noise-measurement workspace built around traceable calibration, explainable Measurement Integrity, frequency analysis, occupational exposure assessment and reviewable evidence—not just a decibel number.
Free evaluation available. Professional is a one-time lifetime unlock with no subscription.
Measurement IntegrityEvidence, warnings and invalidating conditions are recorded with every serious measurement.
Live SPL + history + frequencyLAF, LAS, LAeq, LCpeak, time trace and octave / FFT analysis in one workflow.
A specialist measurement instrument for studios, consultants, audio professionals, venue operators and anyone who needs results with context—not naked dB numbers.
CalibratedTraceable input profiles
InspectableTime, frequency and statistics
DefensiblePDF, CSV, JSON and manifest exports
A more serious measurement workflow
From live reading to documented evidence.
SPL Reference is designed as a measurement workflow, not merely a live sound-level display. Capture, review, classify, organise and export each measurement with the hardware and calibration context that gives the result meaning.
02
Calibrate the chain
Create input-path profiles for the microphone, interface, channel, gain and sample rate, then validate the path acoustically so the app knows when the result is reference-calibrated or merely indicative.
03
Review and organise
Study the saved Overview, Time, Frequency and Statistics views; add notes, photographs and project context; inspect occupational-exposure evidence and integrity findings.
04
Export evidence
Generate a professional report package including PDF, JSON, CSV, charts, event markers and integrity manifest for transparent sharing and later review.
Typical professional chain
Built-in or external mic→iPhone / interface input→Calibrated profile→Measurement + integrity review→Report package
Live measurement
Start with the measurement view built for real work.
The opening screen is not a toy meter. It combines the primary level display, equivalent level, peak data, live time history, event marking, saved-session access and a dedicated calibration path.
- Large primary level readout with selectable detector focus.
- Live LAF / LAeq history chart with markers and ongoing duration.
- Immediate access to Sessions, Calibrate and Settings from the bottom bar.
- Plain-language contextual labels such as Quiet and Low exposure.
Why this screen mattersThe measurement screen communicates that SPL Reference is a workspace. You are not just observing a number—you are recording a result that can later be reviewed, interpreted and exported.
Saved measurement overview
Every session keeps its identity and context.
The Overview view summarises the measurement identity, active duration, project assignment, noise-exposure status and the essential acoustical results. It is the bridge between live capture and professional reporting.
- Clear summary of LAeq, LCeq, LAFmax, LCpeak and c–A difference.
- Notes, photographs and project context remain attached to the session.
- Measurement status and duration stay visible for traceability.
Occupational exposure
Inspect NIOSH / OSHA exposure, not just sound level.
Noise-exposure evaluation has its own visual language because it answers a different question: not only “how loud is it?”, but also “what dose is accumulating?” and “what is projected across the selected assessment horizon?”
- Retrospective assessment display with measured and projected dose logic.
- Duration, current LAS, TWA, projected dose, LEX,8h and LCpeak shown together.
- Suited to occupational measurements and hearing-risk workflows.
Time and frequency analysis
Study what happened over time and across the spectrum.
The saved analysis views are where the app stops being just a meter and becomes a reference tool. Time history, event markers and spectrum snapshots can all be revisited after the live measurement has ended.
- Time view aligns LAF, LAeq and event markers across the stored measurement.
- Frequency view supports 1/3 octave, 1/1 octave and spectral history context.
- Useful for room surveys, noise investigations and repeatable comparison work.
Statistics
Exceedance values and background context stay inspectable.
The Statistics view makes exceedance levels visible rather than hiding them in a report footnote. That matters for environmental context, background characterisation and any workflow that relies on percentile descriptors.
- Ln exceedance values such as L1, L5, L10, L50, L90, L95 and L99.
- Useful background and prevailing-noise context alongside the main SPL metrics.
- Complements the Time and Frequency tabs for deeper review.
Core differentiators
The features that make SPL Reference a professional choice.
Instead of pretending to be a certified instrument by slogan, SPL Reference shows the calibration path, records the evidence, and makes limitations inspectable.
Measurement Integrity
Explainable classifications such as Reference, High, Moderate, Limited and Invalid reveal why a result should—or should not—be trusted.
Traceable calibration
Create reusable input-path profiles binding microphone identity, interface, channel, gain, sample rate and supporting calibration metadata.
Frequency analysis
Study 1/3 octave, 1/1 octave and FFT-oriented behaviour rather than relying on a single broadband number.
Occupational exposure
Evaluate NIOSH, OSHA PEL, OSHA Action Level or custom models using measured and projected dose workflows.
Professional evidence exports
Create human-readable reporting and machine-readable evidence packages including PDF, JSON, CSV, charts and manifest files.
Local-first privacy
No account, no tracking SDKs and no forced cloud workflow. Measurements remain local by default and sharing is user initiated.
Professional reporting
Human-readable reporting. Machine-readable evidence.
A completed measurement can be exported as a structured package rather than being reduced to a screenshot.
A4 PDFSix-page client-ready report
JSONVersioned session data
CSVMetadata, time history, spectrum and markers
ManifestIntegrity file with SHA-256 digests
01
Document the session
Configuration, hardware path, calibration, charts, statistics and integrity findings remain attached to the measurement.
02
Generate the package
Export the client-ready PDF together with structured evidence files that can be archived, inspected or recalculated later.
03
Share transparently
Move beyond screenshots and ambiguous claims by sharing a report package that explains what was measured and under which conditions.
Free versus Pro
Begin with a useful tool. Upgrade for the full evidence.
| Feature | Free | Pro |
|---|---|---|
| Live SPL measurement | ✓ | ✓ |
| Saved measurements | Limited | Unlimited |
| Projects | 1 | Unlimited |
| External microphone and interface profiles | — | ✓ |
| Acoustic calibration and calibration history | — | ✓ |
| Time, Frequency and Statistics saved analysis | — | ✓ |
| Occupational-noise evaluation | — | ✓ |
| Notes, photographs and location evidence | — | ✓ |
| Professional PDF reports | — | ✓ |
| CSV, JSON, charts and manifest exports | — | ✓ |
FAQ
Questions a serious user will actually ask.
What is DSR SPL Reference?
DSR SPL Reference is a professional iPhone sound-measurement workspace that combines live SPL monitoring, calibration-aware measurement, saved analysis, occupational-noise evaluation, Measurement Integrity review and professional reporting.
Can it work with an external measurement microphone?
Yes. Professional access is designed around reusable hardware profiles that can document the microphone, interface, input channel, gain, sample rate and related calibration evidence for the active measurement chain.
What does Measurement Integrity mean?
Measurement Integrity is the app’s explainable evidence layer. It classifies completed measurements according to the calibration state and the actual conditions observed during capture, including overload, clipping, route changes, backgrounding, under-range periods, missing metadata and related limitations.
Does the app include occupational noise assessment?
Yes. The app can evaluate measurements using NIOSH, OSHA PEL, OSHA Action Level and custom models, retaining inspectable interval evidence rather than collapsing the result into a single opaque number.
What can be exported?
A professional evidence package can include a six-page A4 PDF report, versioned session JSON, measurement metadata CSV, time-history CSV, spectrum CSV, event-marker CSV, presentation charts and an integrity manifest with file digests.
Is DSR SPL Reference claiming IEC Class 1 or Class 2 certification?
No. The app applies professional measurement principles and documents calibration and integrity, but it does not by itself claim instrument certification, legal compliance or standards conformity.
DSR SPL Reference for iPhone
Measure sound with context, not just confidence theatre.
Start with the free evaluation, then unlock Professional for calibration, advanced analysis, occupational-noise workflows, projects, evidence capture and professional reporting—all as a lifetime one-time purchase.
Measurement results depend on the microphone, interface, calibration, placement, device configuration and measurement conditions. DSR SPL Reference applies professional measurement principles and documents measurement integrity, but does not by itself claim instrument certification, standards conformity or legal compliance.