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Speech Intelligibility

STI-PA results screens

2.Play the signal over the loudspeaker and then locate yourself in the appropriate zone/room.

3.Verify that the range setting is appropriate for the level being measured. It is desirable to select the longest range that does not overload. (To change the range, press Up/Down Arrows from the STI-PA screen.)

4.Press the Run key to begin your study.

5.The meter will run for 15 seconds and then pause.

To continue to take measurements, repeat step 3.

To terminate your study, please see step 6.

6.Press the Stop key to end your study. (Three viewable results screens are explained in the next section.)

STI-PA results screens

The test signal is made up of 7 octave band signals which encompasses a combination of vowels and syllables from common speech. There are 14 modulating frequencies that emulate a male/female’s speech patterns. The STI method is based on the determination of the modulation transfer function (MTF) which is the ratio of measured modulation to the overall signal strength at each modulation frequency.

Viewing STI-PA results

1.Once in pause or review mode, press repeatedly to toggle through the STI-PA results screen.

STI-PA measurement and scale results screen

In the STI-PA measurement screen, the MTF is combined according to IEC 60268- 16 and presented on a scale between 0 to 1 representing the quality or intelligibility of the mass notification system.

Range

STI-PA scale results

STI-PA results

graphical view

Figure 6-21: STI-PA measurement (scale results) screen

Models SE and DL

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3M DL, SE user manual STI-PA results screens, STI-PA measurement and scale results screen,  Viewing STI-PA results