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
Accredited labs
20
Countries
Showing 276–300 of 393 labs
Paragon Scientific
Active
Refractive Index
Capillary Viscometer Calibration
2.92 mm systems (continued)
Liquids
Density in Air at 20
+ 3 more
Particle Technology
Active
MIL-STD 810D, Method 510.2
MIL-STD 810E, Method 510.3
MIL-STD 810G:2008 Method 501.5
MIL-STD 810F, Method 510.4
MIL-STD-810H, Method 510.7
+ 3 more
Pennington Choices
Active
(HSG 264, 2012)
and Appx. 3 of HSG 227 (2004))
Executive guides HSG 264 (2012)
Perry Analytical
Active
(HSG 248) – 2021
(PCM) based on HSG 248
Manual based on HSG 248
Poulten Selfe and Lee
Active
TEMPERATURE
Viscosity constant ‘C’
Reference viscometers:
ASTM D4052 (Digital density
External (Tip) Diameter
Helix (lead) total deviation (F
GEARS SPUR/HELICAL EXTERNAL (cont’d)
As for Involute Spline Gauges
ISO 6579-1
ISO 15213-2
ISO 11290-1
ISO 7932
F100 based on BS EN ISO
+ 3 more
Pullman Instruments (UK)
Active
DC CURRENT
Measurement
DC VOLTAGE
AC Current Generation
DC RESISTANCE (cont’d)
+ 3 more
Quality Consultants (NI)
Active
(HSG 248) – 2021
(PCM) based on HSG 248
QSOP 03 based on HSG 248
R-TECH Services
Active
ÖNORM EN ISO 17637
BS EN ISO 15614-1:2017
ASTM A 370
DIN EN 10080
BS EN ISO 9015-1:2011
+ 3 more
Ramcare
Active
DC CURRENT
DC VOLTAGE
thermometer Pt100
ROTATIONAL SPEED
Generate
+ 3 more
Rhopoint Metrology
Active
(Steel and tungsten carbide)
LENGTH (cont’d)
pneumatic tyres (See Note 1)
LENGTH (cont.)
Plain plug gauges (taper)
+ 3 more
Richard L Thomas Associates
Active
(HSG 264, 2012)
HSG 264 (2012) and Appx. 3 of
HSG 227 (2004))
Appendix 5 of HSG 227 (2004))
(HSG 248) – 2021
OP11 based on HSG 248
(PCM) based on HSG 248
OP04 based on HSG 248
SARIA
Active
AM-01 based on BS 4401:Part 1:
AM-32 based on BS 4401:Part 4:
AM-03 based on BS ISO 937:2023
AM-04 based on BS ISO
AM-31 based on BS EN ISO
+ 3 more
SATRA Technology Centre
Active
ISO 4931:1986 (withdrawn)
ISO 3759:1984 (withdrawn)
DIN EN 13759
DIN EN 12150-1
DIN EN ISO 15797
+ 3 more
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