The 1990s: Nokia’s rise gave acoustics research a boost
The Otaniemi Acoustics Lab did groundbreaking work in speech synthesis and speech acoustics in the 1980s. The dormant field blossomed with the growth of the mobile phone industry.
The pioneers of acoustics research in Finland, Matti Karjalainen and Unto K. Laine, started working together as tech students while experimenting with electronic music. During a wild weekend in a lab at the Tampere University of Technology, the two friends created fun sounds [some of them] resembling a human voice.
Professor Boris Segerståhl suggested that Laine and Karjalainen begin developing a machine that speaks Finnish. ‘We were eager to go along despite being total rookies in speech acoustics,’ Laine recalls.
At the time, text-to-speech synthesizers were cabinet size computers. An integrated circuit on a silicon chip had just come on the market, enabling Laine and Karjalainen to build a portable device, Synte 2, which aroused global interest.
In the early 1980s, acoustics research in Finland was still at its infancy. There were few tools and very little research. Despite this, the Otaniemi campus boasted three high-quality anechoic rooms.
Acoustics research gained momentum when Karjalainen (1946–2010) was appointed associate professor in acoustics in 1980 and full professor in 1986.
He was followed by his colleague and musician friend Unto K. Laine, who was the first to get a PhD in acoustics at the Helsinki University of Technology (HUT), in 1989. Laine served as Professor of Speech Technology at Aalto University until 2015.
In his dissertation at HUT, Laine improved the acoustics theory used in speech synthesis. The previous model had ignored the way in which sounds radiating from the mouth opening influence the resonance of the vocal tract – the area between lips and the vocal cords.
‘A device without a complex control mechanism and built according to the dominant theory over-amplified the open /a/ and /æ/ sounds, whereas the closed /y/ and /u/ sounds were too closed. They didn't sound like the same person’s vowels,’ says Laine. ‘The acoustic theory of speech production and its practical approximations needed improving.’
Computer simulations made by Laine provided a new perspective on the interaction between sound radiation and the vocal tract. This resulted in the patented vocal tract model PARCAS.
In the 1990s, acoustics research rapidly grew from a small field to the significant global position it now occupies.
‘Nokia had a pressing need for graduate engineers with an understanding of speech acoustics, speech coding and digital signal processing,’ says Laine. ‘We trained hundreds of engineers for the mobile phone industry.’
Laine says that Karjalainen, who headed the lab, possessed the courage to embark on new paths and to focus on topics that had remained relatively unresearched in Finland. Karjalainen took it upon himself to develop research tools that were not available in the early days of digitalisation and created software for sound and speech research.
‘We had a good, creative atmosphere. We were allowed to do, to experiment and innovate.’
In the 1990s, the university launched new research in psychoacoustics, room acoustics and music acoustics, among other fields, all of which now have their own chairs at Aalto University.
Text by Terhi Hautamäki