BS EN 60268-16:2011

FOREWORD
INTRODUCTION
1 Scope
2 Normative references
3 Terms and definitions
4 Description of the STI method
5 Direct method of measuring STI
6 Indirect method of measuring STI using the impulse
  response
7 Measurement procedures, post-processing of data
  and applications
8 Use of STI as a design prediction tool
Annex A (normative) - Speech transmission index (STI)
        and revised STI methods
Annex B (normative) - STIPA method
Annex C (normative) - STITEL method
Annex D (informative) - RASTI method (obsolete)
Annex E (informative) - Qualification of the STI and
        relationships with other speech intelligibility
        measures
Annex F (informative) - Nominal qualification bands
        for STI
Annex G (informative) - Examples of STI qualification
        bands and typical applications
Annex H (informative) - Non-native listeners
Annex I (informative) - Effect of age-related hearing
        loss and hearing impairment on speech
        intelligibility
Annex J (normative) - Calibration of STI test signal
        level
Annex K (informative) - Example test report sheet
        for STI measurements
Annex L (normative) - Prediction of STI using
        statistical methods
Annex M (informative) - Adjustments to measured STI
        and STIPA results for simulation of occupancy
        noise and different speech levels
Annex N (informative) - Other methods of determining
        speech intelligibility
Bibliography
Annex ZA (normative) - Normative references to
         international publications with their
         corresponding European publications

Describes objective methods for rating the transmission quality of speech with respect to intelligibility.

This part of IEC 60268 specifies objective methods for rating the transmission quality of speech with respect to intelligibility.

The objective of this standard is to provide a comprehensive manual for all types of users of the STI method in the fields of audio, communications and acousti cs.

This standard does not provide STI criteria for certification of transmission channels (e.g . criteria for a voice-alarm system).

Three methods are presented, which are closely related and are referred to as STI, STIPA, and STITEL. The first two methods are intended for rating speech transmission performance with or without sound systems. The STITEL method has more restricted uses.

NOTE None of the methods are suitable for the measurement and assessment of speech privacy and speech masking systems , as STI has not been validated for conditions that represent speech privacy applications [1] 1.

The following information is included:

• measurement techniques ;

• prediction techniques.