APx STI Plugin v2

Size283.7 MB
Create DateMarch 11, 2022
Last UpdateJanuary 17, 2023

For designers of public address, flight recorder and police/fire/emergency communications systems, the APx Speech Transmission Index (STI) plugin is a software add-on for the APx500 that provides a STIPA measurement and Speech Level measurement conforming to international standard IEC 60268-16 (2011).

Technote 128: Speech Transmission Index Measurement with APx Audio Analyzer


  • The STI plugin is a software option and requires the purchase of an iButton (APX-SW-STI) for measurement functionality. Download and installation of the plugin, without an iButton, enables the measurement in demo mode only.
  • APx STI plugin v2.0 requires v4.5 or later of APx500 audio test software. (For earlier versions of APx500 audio software, please use APx STI v1.1.)
  • The STI plugin utilizes a noise-based stimulus. For speech intelligibility measurement using real speech, please see the APx ABC-MRT plugin.
APx STI Plugin Setup
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