# STIPA - Speech Intelligibility — IEC 60268-16 PA System Tester

> IEC 60268-16 PA System Tester (iPhone/iPad app by Yumm One.)

- Source: https://appshunter.io/ios/app/stipa-speech-intelligibility/id6756669181 (this page in markdown: same URL + `.md`)
- Developer: [Yumm One](https://appshunter.io/developer/1588876379)
- Category: Music, Utilities
- Price: $39.99 with in-app purchases
- Age rating: 4+
- Requires: iOS 17.0 · 3 MB
- Languages: American English
- Released: 2025-12-18
- Data updated: 2026-08-01
- User reviews in markdown: https://appshunter.io/ios/app/stipa-speech-intelligibility/id6756669181/reviews.md

## What is STIPA?

STIPA is the professional speech intelligibility measurement tool trusted by audio engineers, fire safety professionals, and acoustic consultants worldwide. Fully compliant with IEC 60268-16:2011 standards, STIPA delivers laboratory-grade accuracy in a portable iOS app.

PROFESSIONAL STI MEASUREMENT

Accurately measure the Speech Transmission Index of any public address system, voice evacuation system, or audio installation. STIPA uses the standardized modulation transfer function method across seven octave bands to deliver results you can trust for compliance documentation and system optimization.

COMPLIANCE READY

Meet the requirements of critical industry standards:

- IEC 60268-16:2011 Speech Transmission Index measurement
- NFPA 72 voice intelligibility requirements for fire alarm systems
- ANSI/ASA S12.60 classroom acoustics verification
- ADA accessibility compliance for educational facilities

PROFESSIONAL FEATURES

Real-Time Analysis
- Live STI value with IEC qualification display
- Seven octave band level monitoring (125Hz to 8kHz)
- Modulation index visualization for each frequency band
- Signal quality indicators for measurement confidence

Comprehensive Reporting
- Generate professional PDF reports for client documentation
- Export data in CSV format for further analysis
- JSON export for system integration
- Include location names, notes, and timestamps

Measurement Flexibility
- Support for external calibrated microphones
- Adjustable measurement duration for various environments
- Built-in STIPA test signal generator
- Works with any PA system or audio source

Data Management
- Save unlimited measurements with searchable history
- Compare results across locations and time
- Track system performance over multiple visits
- Statistics dashboard for trend analysis

WHO USES STIPA

Fire Safety Professionals
Test voice evacuation systems and emergency communication systems for NFPA 72 compliance. Document speech intelligibility across all acoustically distinguishable spaces.

AV Integrators
Commission PA systems with confidence. Verify speech clarity meets client specifications and industry benchmarks. Troubleshoot problem areas with octave band analysis.

Acoustic Consultants
Assess room acoustics and their impact on speech transmission. Identify reverberation and noise issues affecting intelligibility. Provide quantitative data for remediation recommendations.

Educational Facility Managers
Ensure classroom audio systems meet ANSI S12.60 requirements. Document ADA compliance for hearing accessibility. Optimize learning environments with data-driven decisions.

Houses of Worship
Verify sermon intelligibility throughout the sanctuary. Optimize sound system performance for clear communication. Ensure all congregants can hear spoken content clearly.

UNDERSTANDING STI RESULTS

- Excellent (0.75-1.00): Outstanding speech clarity
- Good (0.60-0.75): Clear and intelligible speech
- Fair (0.45-0.60): Acceptable with some difficulty
- Poor (0.30-0.45): Speech understanding is strained
- Bad (0.00-0.30): Speech is largely unintelligible

TECHNICAL SPECIFICATIONS

- Sample Rate: 48kHz
- Frequency Range: 125Hz - 8kHz (7 octave bands)
- Modulation Frequencies: 14 per IEC 60268-16
- Measurement Duration: 10-60 seconds configurable
- External Microphone Support: Lightning and USB-C audio interfaces

SUBSCRIPTION OPTIONS

STIPA offers flexible options for every professional need:

- Monthly subscription for project-based work
- Annual subscription for ongoing testing requirements
- Lifetime purchase for permanent access

Download STIPA today and bring professional speech intelligibility testing to every job site.

Privacy Policy: https://audiomillo.com/privacy
Terms of Service: https://audiomillo.com/eula

## Pricing and in-app purchases

Base price: $39.99.

**Subscriptions**

| Subscription | Price | Period |
| --- | --- | --- |
| Pro Yearly | $149.00 | per year |
| Pro Monthly | $29.99 | per month |


## Chart rankings

- #199 in Top Paid · Music (US App Store)


## Version history (last 4 releases)

### 1.0.3 — 2026-06-20

Input channel selection now works correctly
- Version 1.0.2 added the ability to choose a channel on a multichannel USB / Lightning audio interface, but the app still analyzed the operating system's default input - the mixed/main signal - instead of the channel you picked. This update makes the selection take effect, on both iPhone/iPad and Mac.
What was fixed:
- The chosen input channel is now routed directly from the audio interface into the analyzer, so only that channel is measured - not a downmix of the whole device.
- Your channel choice is remembered between sessions and restored automatically when you reconnect your interface.

### 1.0.2 — 2026-06-16

Reference-grade measurement accuracy + multichannel audio support
This update fixes an issue where a direct signal-path (loopback) test — feeding the built-in STIPA signal straight into the input with no loudspeaker, microphone, room, or noise — reported a stuck reading around 0.30 instead of the near-perfect score expected for an ideal path. Clean measurements now read close to 1.00.

What was fixed:
- Rebuilt the STIPA test signal to the IEC 60268-16 method using band-limited noise carriers with true intensity modulation (the old signal compressed its own modulation depth).
- Rewrote the modulation analysis to measure the intensity envelope at the exact modulation frequencies, with sharper octave-band filtering.

New:
- Input-channel selection for external multichannel USB / Lightning audio interfaces (Settings → Audio → Input Channel).

### 1.0.1 — 2026-04-11

- Corrected the modulation frequency table used for STIPA analysis. All seven octave bands (125 Hz – 8 kHz) now use the exact modulation frequencies specified in IEC 60268-16:2011. This was the primary cause of near-zero STI results when using external STIPA sources such as NTI STIPA noise.
- Fixed the octave band bandpass filters. A unit mismatch in the filter design formula caused all seven filters to pass the full-spectrum signal instead of isolating their respective octave bands, further degrading measurement accuracy.
- Improved the envelope follower response so that modulation frequencies up to 12.5 Hz (required for the 4 kHz and 8 kHz octave bands) are measured accurately.
- Fixed a conflict that could disable microphone input when using the built-in test signal generator alongside live measurement.

### 1.0.0 — 2025-12-19

No release notes.

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*Data collected daily from the US App Store and indexed by [AppsHunter](https://appshunter.io/). User reviews are verbatim App Store reviews. Ratings, prices and chart positions refresh continuously; this snapshot is from 2026-08-01.*