Acceptance Measurements of Emergency Warning Systems
The demands for emergency warning systems can be found in the following standards:
- DIN EN 60849 (IEC 60849 and VDE 0828): Sound Systems for Emergency Purposes
- IEC 60268-16: Sound System Equipment, Objective Rating of Speech Intelligibility by Speech Transmission Index
- DIN VDE 0833-4 Appendix G: Measuring Methods for the Determination of the Speech Transmission Index STI
The intention is to capture the speech intelligibility in a single parameter (STI) by means of objective measurement.
Speech intelligibility can be affected by outside influences (noise), room acoustics (reverb, echoes), as well as sound system deficiencies (shortened frequency response, too high or low level, distortion)..
Speech intelligibility is measured either by feeding a dedicated test signal into the system while evaluating the premises with a mobile NTI Acoustiyzer, or by analyzing the impulse response, recorded with Monkey Forest, according to the Schroeder method.