This test method provides an objective measure of speech intelligibility in acoustic environments using the Speech Transmission Index (STI) method. STI quantifies how well speech is transmitted through an acoustic space, accounting for noise, reverberation, and frequency distortion. The measurement is critical for evaluating communication effectiveness in public address systems, conference rooms, classrooms, and other speech-critical environments. Venues with high standards for speech clarity use this method to verify system performance and acoustic suitability. ISO 17025 accreditation ensures reliable assessment of speech intelligibility compliance with design standards.
What it measures
Speech Transmission Index (STI) value (0-1 scale)
Modulation transfer function across frequency bands
Speech intelligibility rating and quality assessment
Impact of noise and reverberation on speech clarity
Communication effectiveness and auditory conditions
requirements of HTM 01-06 Part E35 °C/3 days based on HTM 2030Part E, WHTM 01-06 Part E & BS ENISO 15883-4 using R2A andPart E, HTM 0106 Part E, WHTM 01-+ 3 more
Audio and sound system designPublic address and emergency systemsTelecommunications and broadcastingEducational and institutional facilitiesAviation and maritime communication
Related Standards
ISO 3382-2Acoustics - Measurement of room acoustic parameters - Part 2: Reverberation time in ordinary rooms
ISO 1996-2Acoustics - Description, measurement and assessment of environmental noise - Part 2: Determination of sound pressure levels
EN 60268-1Sound system equipment - Part 1: General
Scope