Enhanced Speech Transmission Index measurements through combination of indirect and direct MTF estimation

摘要

The Speech Transmission Index (STI) is an objective measure that predicts speech intelligibility. Test signals are played back through a channel under test. An STI analyzer at the channel output calculates an index between 0 and 1, indicating intelligibility. Over the years, various test signals have been used for measuring the STI, all based on the same principles but differing in the modulation frequencies tested and octave bands covered by the signal. The invention disclosed is a new method for constructing test signals: not just the transfer of modulations on a carrier signal is analyzed, but also the carrier signal itself This apprach leads to more accurate STI measurements that correspond more closely to the ideal (theoretical) STI and to subjective speech intelligibility. Shorter measuring times are achieved without compromising the accuracy of the measurement, while extending the range of systems to which the STI can be reliable applied.