Scope
IEC 60268-16:2011
Speech Transmission Index Measurement
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
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DIN EN ISO 3382-2
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BS EN ISO 3382-2
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NF EN ISO 3382-2
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UNI EN ISO 3382-2
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UNE EN ISO 3382-2
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NEN EN ISO 3382-2
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DIN EN ISO 1996-2
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BS EN ISO 1996-2
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NF EN ISO 1996-2
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UNI EN ISO 1996-2
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UNE EN ISO 1996-2
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NEN EN ISO 1996-2
1,868
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DIN EN ISO 11127-6
DIN EN 13727
1) BS EN ISO 11930:2019+
2) QMIC WI 22, based on BS EN
Air Surveys
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(HSG 248) – 2021
APP 7 based on HSG 248
(PCM) based on HSG 248
(PCM) based on HSG 248)
APP 15 based on HSG 248
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BS EN ISO 16283-1:2014+A1:2017BS EN ISO
BS EN ISO 140-4:1998
ISO 1407
ISO 7171
BS EN ISO 9972:2015
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(HSG 248) – 2021
AEC 1 based on HSG 248
(PCM) based on HSG 248
AEC 6 based on HSG 248
Airtech Analysis
Active
(HSG 248) – 2021
(PCM) based on HSG 248
staining based on HSG 248
(HSG 264, 2012)
Appendix 5 of HSG 227 (2004))
BS ISO 18283:2022
ASTM D2234 (location E)
ASTM D2013 (location B)
BS ISO 5074:2015; and
ASTM D409:2016
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Alkali Environmental
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BS EN ISO 16911-1:2013 using
DIN EN 14181
DIN EN 13126-19
DIN EN 15058
DIN EN 14789
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Allied Aerosystems
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DC Resistance
2.92 mm systems (continued)
DC VOLTAGE
AC CURRENT
DC Power
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Amentum Clean Energy
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OM H-3 based on ISO 9698:2019
ISO 9696:2017 and ISO
(HSG 248) – 2021
(PCM) based on HSG 248
staining based on HSG 248.
Amentums Materials Testing and Research Laboratory part of Energy Safety and Risk Consultants (UK)
Active
a) BS 7270:2006
b) BS 3518-3:1963 (Withdrawn)
ASTM E1820-18ae1 (Withdrawn)
ISO 6892-2
BS EN ISO 204
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Anchem Laboratories
Active
(HSG 248) – 2021
ANC/AS/2 based on HSG 248
DIN EN 14791
IEC 60519-11
DIN EN 13284-1
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Andersen Caledonia
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requirements of HTM 01-06 Part E
35 °C/3 days based on HTM 2030
Part E, WHTM 01-06 Part E & BS EN
ISO 15883-4 using R2A and
Part E, HTM 0106 Part E, WHTM 01-
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Apex Acoustics
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BS EN ISO 16283-1:2014+A1:2017BS EN ISO
BS EN ISO 16283-2:2020
HTM 08-01 - 2013
BS EN ISO 140-4:1998
BS EN ISO 717-2:2020
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