Ivie IE-45 STI-PA - Speech Intelligibility Analysis - Manual

Rev. 06Dec2006
SPECIAL NOTE: For accurate test results, the IEC 60286-16 standard needs to be observed
under all conditions and circumstances.
GETTING STARTED
STEP 1 - Make certain that the Ivie STI-PA program has been calibrated. If you are not certain
of the Calibration status you can view "Calibration" help file for more detail. Look for "HOW
CAN I TELL IF MY IE-35 IS CALIBRATED?"
STEP 2 - Open and Name a New File for this job. Press "File" and then "New Job.." Set up File,
Area, and location. You can view "Opening a NEW JOB" help file for more detail.
Note: In the following three steps, the level setting window enables a quick visual check to be
made of the ambient noise and signal levels as STI-PA measurements are being made. Provided
that the audio signal does not overload the IE35 microphone input, the window setting itself does
not affect the STI-PA measurement results but is there to ensure that the STI-PA signal levels are
meeting the required target SPL values.
Step 3 - Set the Sound Pressure Level Target to the level at which measurement is to be made.
Press "Option" the "Set Target SPL Reference..." and use the Up/Down arrows in the Target
SPL: window to set the SPL at which the test will be performed. This level is determined by the
actual sound level that will be used in the room for normal operation. For example, if the voice
announcement will be at 85 dB SPL then set the Target SPL level to 85 dB.
Step 4 - The "Target Range" is typically set for 10 dB. You should not need to change this
setting.
Step 5 Set the "Max Ambient" to approximately 20 dB below the "Target SPL". This enables a
check on the signal to noise ratio to be made but does not affect the measurement itself. Ideally,
a voice announcement (and hence the STI-PA signal replay level) should be at least 10 – 15 dBA
above the background noise level. The usual objective when using STI-PA, is to measure the
intelligibility performance of a PA system under its normal working conditions. However, by
increasing the signal to noise ratio to > 20 dBA, the effect of the intelligibility deterioration due
to the background noise is effectively removed, and the residual loss due to room reverberation
or other factors can be identified. This technique should therefore be used for Diagnostic
purposes only or to make a “noiseless” measurement that can later be used to mathematically
calculate the effect of different signal to noise ratio conditions.
Step 6 - Press the "OK" button to exit the Target SPL window.
Step 7 - Press the "Options" menu and the select "Preferences". Select either the Male or Female
Voice Signal Gender. Typically, the Male Voice Gender is used. This is the default setting for
the Voice Signal Gender.
Step 8 - Connect your CD or Wave file player to the sound system and adjust the playback level