Measurement of speech transmission index

The speech transmission index (STI) is a widely used objective evaluation parameter of speech intelligibility. Although the IEC standard commits to providing a definite STI technical specification, the application of STI in natural sound rooms and auditoria in recent years revealed that some factors that may cause relatively large errors have not been considered, which results in a lack of comparability between the measured data of different rooms according to current standards. Based on the research progress in recent years, these possible influencing factors are analyzed and solutions are proposed to promote the application of STI methods in the field of architectural acoustics.