Gallo Acoustics don’t make boxy speakers, there’s a better way in eliminating resonance and internal diffraction, the two main causes of loudspeaker distortion.
Speech Intelligibility STI
Speech intelligibility is measured by reproducing a known signal (the STIPA test signal) and measuring the quality of that signal as it reaches each of the measurement positions. The IEC 60268-16 standard for STI defines how any degradation in the signal is measured and the intelligibility result displayed as a single number from 0 (unintelligible) to 1 (excellent intelligibility). Measurement units are STI (Speech Transmission Index) or CIS (Common Intelligibility Scale).
Factors that influence the intelligibility of speech
sound pressure level (speech must be loud enough, but not too loud)
ambient noise level (e.g. crowds or passing traffic)
reverberation time RT60 (sound reflects off smooth surfaces; we need some reflections but not too many)
Also, if a Public Address (PA) system is being used for the announcements
frequency response of the PA system (e.g. too much bass)
signal-to-noise ratio (i.e. quality of the system)