A revised speech spectrum for STI calculations

Morales, L; Leembruggen, G; Dance, S; Shield, BM

Abstract

The ability of the Speech Transmission Index (STI) to predict speech intelligibility under noisy conditions is
highly dependent on the assumed spectrum of the speech signal. Examination of the literature showed that the
long-term average speech spectrum of male talkers differs substantially from the speech spectrum recommended
for STI calculations (IEC 60268-16). To explore these issues, the long-term average speech spectrum of forty
male British English people was first measured, compared with the available literature and proposed for STI
calculations. Then, using several voice alarm systems, the influence of the measured spectrum on STI calculations
was assessed and comparisons made with the standard speech spectrum. The results showed significant STI
differences under noisy conditions and considerable reductions in the required electrical power with the use of
the new proposed male spectrum. This indicated that the current STI method could benefit from a revised speech
spectrum.

Citation

Morales, L., Leembruggen, G., Dance, S., & Shield, B. (2018). A revised speech spectrum for STI calculations. Applied Acoustics, 132, 33-42. https://doi.org/10.1016/j.apacoust.2017.11.008

• Journal Article Type: Article
• Acceptance Date: Nov 13, 2017
• Online Publication Date: Nov 21, 2017
• Publication Date: Mar 1, 2018
• Deposit Date: Apr 25, 2018
• Publicly Available Date: Nov 21, 2018
• Journal: Applied Acoustics
• Print ISSN: 0003-682X
• Publisher: Elsevier
• Volume: 132
• Pages: 33-42
• DOI: https://doi.org/10.1016/j.apacoust.2017.11.008
• Publisher URL: https://doi.org/10.1016/j.apacoust.2017.11.008
• Related Public URLs: https://www.journals.elsevier.com/applied-acoustics