Accurate Speech Intelligibility Assessment for Acoustic Performance
PackSound provides professional Speech Transmission Index (STI) Testing services to evaluate and measure speech intelligibility within indoor and outdoor environments. STI testing is a critical acoustic assessment method used to determine how clearly spoken communication can be understood by listeners in a given space.
Using advanced STI-certified instruments and internationally recognized testing procedures, our experts assess the effectiveness of public address systems, emergency communication systems, classrooms, auditoriums, transportation hubs, and commercial facilities. The results help identify acoustic deficiencies and provide actionable recommendations to improve speech clarity and overall communication performance.
Whether you’re designing a new facility, validating an installed sound system, or ensuring compliance with acoustic standards, PackSound delivers reliable STI measurements and detailed reports to support informed decision-making.
What is Speech Transmission Index (STI) Testing?
Speech Transmission Index (STI) is an internationally accepted metric used to evaluate speech intelligibility in a space. The STI score ranges from 0.00 to 1.00, where higher values indicate better speech understanding.
STI testing measures how room acoustics, background noise, reverberation, and sound system performance affect speech transmission. It is widely used to assess the effectiveness of public address systems, emergency evacuation systems, conference facilities, educational institutions, healthcare facilities, and other environments where clear communication is essential.
By identifying acoustic challenges that reduce speech clarity, STI testing helps improve user experience, safety, productivity, and compliance with acoustic standards.
Our STI Testing Services Include
Speech Intelligibility Assessment
Comprehensive evaluation of speech clarity throughout the tested area using STI and STIPA methodologies.
Public Address System Testing
Verification of speech intelligibility performance for PA systems in commercial, industrial, and public buildings.
Emergency Communication System Validation
Assessment of voice alarm and emergency broadcast systems to ensure messages remain understandable during critical situations.
Acoustic Performance Analysis
Identification of acoustic factors affecting speech transmission, including excessive reverberation, background noise, and poor sound distribution.
Detailed Technical Reporting
Comprehensive reports including STI score maps, frequency analysis, observations, and practical recommendations for improvement.
Applications of STI Testing
Educational Facilities
Schools
Universities
Lecture Halls
Training Centers
Public Buildings
Airports
Railway Stations
Metro Stations
Government Buildings
Commercial Spaces
Conference Rooms
Boardrooms
Corporate Offices
Shopping Malls
Entertainment & Cultural Venues
Auditoriums
Theatres
Museums
Exhibition Centers
Healthcare Facilities
Hospitals
Clinics
Medical Training Centers
Religious & Community Spaces
Churches
Mosques
Temples
Community Halls
Sports & Event Venues
Stadiums
Arenas
Convention Centers
STI Testing Methodology
At PackSound, STI testing is conducted according to internationally recognized standards, ensuring consistent and repeatable results.
Our process includes:
Site inspection and acoustic evaluation.
Selection of measurement locations throughout the space.
Setup of STI-certified analyzers and calibrated sound sources.
Generation of standardized test signals.
Measurement of speech intelligibility performance.
Analysis of reverberation, noise levels, and sound system effectiveness.
Preparation of detailed reports and improvement recommendations.
Standards Followed
PackSound performs STI testing in accordance with:
IEC 60268-16
STIPA (Speech Transmission Index for Public Address Systems)
RASTI Methodology
Relevant ISO Acoustic Guidelines
Project-Specific Acoustic Requirements
Our testing procedures ensure reliable and industry-compliant results suitable for certification, design validation, and acoustic optimization projects.
Key Benefits of STI Testing
Improved Communication
Ensure speech messages are clearly understood throughout the space.
Enhanced Safety
Improve the effectiveness of emergency announcements and evacuation instructions.
Better User Experience
Create comfortable environments where communication is effortless and effective.
Acoustic Optimization
Identify and resolve acoustic issues affecting speech clarity.
Standards Compliance
Support compliance with industry regulations and project specifications.
Data-Driven Decision Making
Obtain measurable performance data for design improvements and system upgrades.
Why Choose PackSound for STI Testing?
PackSound combines acoustic expertise, advanced measurement technology, and practical engineering knowledge to deliver dependable STI testing services across various industries.
Experienced Acoustic Specialists
Our team has extensive experience in architectural acoustics, sound system assessment, and acoustic performance optimization.
Advanced Measurement Equipment
We utilize STI-certified analyzers and calibrated acoustic instrumentation from leading manufacturers.
Standards-Compliant Testing
All assessments follow internationally recognized acoustic testing standards and procedures.
Detailed Reporting
Receive professional reports with STI score mapping, analysis, and actionable recommendations.
Customized Solutions
Every project receives tailored recommendations based on the unique acoustic characteristics of the space.
End-to-End Support
From testing and analysis to acoustic improvement recommendations, we support clients throughout the entire process.
Frequently Asked Questions
What is a good STI score?
An STI score above 0.60 is generally considered good, while values above 0.75 indicate excellent speech intelligibility.
How long does STI testing take?
Most assessments require between 30 and 60 minutes per room, depending on room size and complexity.
What affects speech intelligibility?
Reverberation, background noise, room geometry, occupancy levels, and sound system design all influence speech intelligibility.
Can STI testing improve emergency communication systems?
Yes. STI testing helps identify areas where emergency announcements may be difficult to understand and provides recommendations for improvement.
Is STI testing required for public buildings?
Many projects, especially those involving public address and emergency voice alarm systems, require STI testing to verify communication effectiveness and compliance.
Do you provide recommendations after testing?
Yes. Every report includes practical recommendations to improve speech intelligibility and overall acoustic performance.