AES Press Release: AES Amsterdam 2008

Keynote Speaker: Tammo Houtgast

For Release: April 20, 2008

 Keynote by Tammo Houtgast, the Godfather of STI


Amsterdam, April 2008: What do optimum sound reinforcement for a poetry slam, an announcement in the central station and a phone call all have in common? They rely on good speech intelligibility. Yet speech intelligibility is a complex value which for a long time could only be quantified by extensive and costly tests with human listeners. So it was a real revolution when, in the early seventies, Tammo Houtgast together with his collegue Herman Steeneken developed a method of measuring speech intelligibility. Now there was a fast, cost-effective and above all objective way of measuring the quality of a speech transmission!


Today, this seems to be self-evident - which is an indication of just how important this invention was. Nowadays known as Speech Transmission Index, STI, Tammo Houtgast’s researches have affected many fields of audio technology subsequently. STI is used as the basis for the approval of evacuation systems and for improving the sound quality of PA systems. Special STI versions have been defined, which can help to judge the quality of any kind of speech transmission channel. STI has become simply a common tool in professional audio technology.


The Audio Engineering Society is proud to present Tammo Houtgast as the keynote speaker for the opening ceremony of the 124th AES Pro Audio Expo and Convention in Amsterdam (May 17 to 20 2008). Please join us on Saturday, May 17, at 12:00 hours in Room B.




More press information about the
AES Pro Audio Expo & Convention in Amsterdam
is available on the AES press web site :






Press Contact: 

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Stefani Renner

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AES - Audio Engineering Society