Public defence in Computer Science, M.Sc.(Tech.) Janne Riionheimo

Title of the thesis: Hearing as Intended: How Differences in Listening Conditions Affect Sound Translation

Thesis defender: Janne Riionheimo 
Opponent: Associate professor Matthias Frank, Institute of Electronic Music and Acoustics (IEM) University of Music and Performing Arts (KUG), Austria
Custos: Professor Tapio Lokki, Aalto University School of Science

In his doctoral research, Janne Riionheimo examines a central problem in sound reproduction: why film soundtracks or carefully mixed music often fail to translate consistently across different listening environments. Sound designers and mixing engineers aim to convey their artistic decisions to audiences as intended. Yet in practice, the reproduced sound changes when listened to in different rooms, on various equipment, or with varying loudspeaker configurations.

Many listeners have noticed that film dialogue can be difficult to understand or that the same piece of music sounds different on headphones, a television, or a car audio system. Riionheimo examines how room acoustics, loudspeaker systems, mixing practices, and audio formats contribute to these differences. The topic is relevant now as spatial audio and multichannel formats have moved into streaming services and headphone playback. The content is increasingly heard in environments for which it was not originally designed.

The work provides new empirical evidence on phenomena that have been widely discussed in the field but not systematically studied. Riionheimo conducted two extensive investigations using controlled listening tests, in which sound fields from real rooms were captured and reproduced in a laboratory for professional assessors. Evaluations were complemented with interviews and statistical analysis.

The results show that listening conditions have a substantial impact on sound translation. In cinemas, excessive reverberation reduces dialogue intelligibility, while in music reproduction, the most notable differences between rooms concern brightness and timbre. Moderate reverberation can enhance spaciousness, whereas an overly dry room may make a lead vocal sound distant and unclear. Multichannel mixes translate more consistently across rooms than stereo, and some established mixing practices may introduce unexpected colorations.

The dissertation offers insight into how listening conditions and mixing decisions together shape the perceived sound. The findings can support the design of listening spaces and the development of audio reproduction systems. They also help mixing engineers and sound designers make decisions that remain reliable across listening conditions and improve the audience experience, whether content is heard in a cinema, at home, or on headphones.

Keywords: room acoustics, sound reproduction, sound character, film sound, spatial sound

Contact information: janne.riionheimo@aalto.fi and https://www.aalto.fi/en/aalto-acoustics-lab 

Thesis available for public display 7 days prior to the defence at Aaltodoc.