MAIN Research interests
Research on room acoustics has provided new methods in measurement and objective analysis of acoustics of different spaces ranging from cars to concert halls.
Properties of different musical instruments influence significantly how the music expressivity is communicated in acoustic spaces to the listener.
High-fidelity reproduction of measured acoustic spaces is crucial for conducting listening experiments. Developed novel methods have been adopted to frequent use also in the industry.
How we experience sound and music is the motivation behind all acoustics. Studies combining acoustics and psychology have opened new substantial research topics.
I am a post-doctoral researcher in the Department of Computer Science, Aalto University School of Science. My main area of research is room and music acoustics acoustics and the principal topics in the Ph.D. thesis were the source emulation (loudspeaker orchestra) in concert hall research, and auralization.
Doctoral defense took place in November 2011.
In September 2015, I started a three-year post as Academy of Finland post-doctoral researcher. Sincere thanks to the Academy of Finland for funding.
Oct 2018: IOA Auditorium Acoustics 2018 paper on combined analysis of perceived music dynamics in concert halls and emotional impact presented by T. Lokki in Hamburg, Germany. Application sent for Academy of Finland research fellow.
Sep 2018: Three journal articles in preparation for JASA.
Aug 2018: Applied digital signal processing course was nominated among the top-10 courses
Jul 2018: Working with IOA Auditorium Acoustics paper and familiarizing with new statistical analysis methods.
Jun 2018: Back in Finland after a very interesting research visit at Aalborg University.
May 2018: Developing new ways to manipulate measured room acoustics in reproduction in spatio-temporal domain, and running experimental listening tests.
Apr 2018: Paper reporting initial findings on the studies on perceptual stretching of musical octaves was presented in Baltic-Nordic Acoustic Meeting (BNAM2018) in Reykjavik, Iceland.
Mar 2018: A three-month research visit to Aalborg University has gotten under way. The tentative working plan includes designing new listening test methods and conducting experiments related to the influence of various acoustic qualitites to the emotional impact of music listening. The research visit will likely extend to prospective research collaboration with B&O.
Feb 2018: A Two co-authored abstracts submitted to IOA Auditorium Acoustics.
Oct 2017: Listening experiments on orchestra instrument tuning and perception of octave intervals are in progress as a collaboration with Jussi Jaatinen from University of Helsinki.
Sep 2017: A course on Applied Digital Signal Processing ELEC-C5340 has started for the autumn semester.
Aug 2017: Akustiikkapäivät was held on 24.-25.8. in Espoo with one own paper presented and contribution to two other papers.
Jun 2017: Two research research topics are presented in the joint ASA Meeting & Forum Acousticum in Boston, MA, USA. One presentation is given in a session related to music dynamics in concert halls, and the topic discusses the potential differences of tonal consonance created by the acoustics of various concert halls. The second topic is presented as a poster, and it proposes a method for enhancing the impression of auditory proximity in binaurally reproduced by modifying the inter-aural level difference (ILD) in the head-related transfer functions used for synthesizing the room response.
May 2017: A journal article has been published in the Journal of the Acoustical Society of America! The topic of the new publication is the comparison of magnitude of effects between two variables in binaural room-acoustic measurements. The variation in the early interaural cross-correlation coefficient (IACC80) is investigated as the functions of varied head-related transfer function (HRTF), and locally varied receiver position. The study applies room-acoustical simulations for various room conditions combined with binaural room impulse response synthesis through HRTFs from the CIPIC database. The article is freely available as open access in the JASA-EL archive.
Mar 2017: A collaboration with a Helsinki University researcher explores the perceptual tuning curve of symphony orchestra instruments. The outlined listening tests investigate the types of the instruments over wide octave regions, and the inclusion of different playing dynamics links the research to other topics on the effect of music dynamics to the auditory perception.
Feb 2017: Time for some room-acoustic simulation for improving a manuscript which explores the uncertainties in the estimation of objective binaural room-acoustic parameters. Earlier simulations were conducted purely in Matlab, and the revised simulations apply more complex room models in Odeon.
Nov 2016: A new journal article has finally been published in the Journal of the Acoustical Society of America. The paper presents subjective listening experiments which aim to resolve whether the acoustics of concert halls render the dynamic contrasts (from piano to fortissimo) differently. Furthermore, we investigated in which respect the overall impression of the sound changes differently depending on the room acoustics. The motivation for the research is rather simple: given that dynamic variations are one of the key ingredients for communicating the meaning of music, it is possible that some concert halls convey the music dynamics better to the listeners. Also, the overall auditory impression might change in certain acoustics more than in others. Our recent research suggests that strong and lateral sound in general enhance the overall impression of music dynamics.
Oct 2016: The research team has moved to another building in Otaniemi area. The new premises will soon include a modified multi-channel listening room with increased reproduction loudspeaker channel number for upcoming listening experiments.
Sep 2016: With Dr. Sakari Tervo, we gave a tutorial presentation at the DAFx’16 conference in Brno, Czech Republic. The presentation included a collection of our recent work, ranging from spatial analysis of room impulse responses to room measurements and data visualization techniques. The slides of the tutorial “Detailed Analysis of Room Acoustics by Spatiotemporal Methods” can be downloaded here.
Sep 2016: A long-time research colleague, Mr. Antti Kuusinen had his dissertation on the subject of method on perceptual evaluation of concert hall acoustics. His career in acoustics continues as a consultant.
Aug 2016: A project for a spatial reverberation in a club environment comprised of adaptation and implementation of a time-variant reverberation algorithm. Earlier, a similar algorithm was applied to the research of virtual research spaces in the Master’s thesis.
Jul 2016: A recent research published in JASA remains still as the third most read article this month in the journal.
Mar 2016: A new article has been published in JASA! The study shows with listening experiments that the acoustics of a concert hall influences the degree of emotional impact elicited by music listening. In brief, we rendered anechoic orchestra music in the acoustics measured in selected European concert halls (Vienna Musikverein, Amsterdam Concertgebouw, Berlin Konzerhaus and Philharmonie, Cologne Philharmonie, and Helsinki Music Centre). The subjects listened to the same music in different acoustics, while we continuously measured their skin conductance. Earlier research has shown that skin conductance corresponds to strong emotional impact. Strong pleasurable stimulation, e.g. by music, activates the sweat glands in the skin due to the autonomic nervous system. The results show that the emotional impact by concert hall acoustics differ from each other. The sound such as that found in the classical shoebox rooms (Musikverein & Konzerthaus) elicit the strongest emotional responses. These findings offer a new approach to the reputation of “excellent acoustics” as they might well evoke stronger emotions in music. After all, emotional experiences are an important aspect in listening to music to many listeners.
Mar 2016: A collaboration paper with Winfried Lachenmayr (Müller-BBM) has been presented in DAGA2016, a German conference on acoustics. The paper shows results from a listening test where the listeners rated the subjective impact of orchestra music recorded live in Berlin Konzerthaus and Berlin Philharmonie. The findings, indicating high impact in Konzerthaus, appear to be in line with an upcoming article about the emotional impact of concert halls.
Feb 2016: A study considering the influence of individual HRTFs to the early interaural cross-correlation coefficient metric (IACCe) is in preparation. The article shows with room-acoustic simulations how much the variation between different directional hearing functions (HRTF) affects the values of IACC in concert hall situations. The effect by HRTF variation is compared to the effect by small variations in the receiver position.
Jan 2016: Revised versions of two large articles have been resubmitted for evaluation. Hopefully the outcomes of the review round will be positive regarding the publication of the studies.
Sep 2015: There are three papers sent to IOA Auditorium Acoustics in Paris with me as the first or other author. The papers present topics of subjective impact by concert hall acoustics, acoustics of the Vienna Musikverein, and analysis of rock and nightclubs.
Aug 2015: Our research group participated in Akustiikkapäivät, which is a bi-annual Finnish conference on acoustics.
Apr 2015: A new journal article in Acoustics Australia discusses the room-acoustic quality in vineyard-type concert halls and their relation to the dynamic responsiveness. The article presents examples of spatiotemporal analyses in Helsinki Music Centre, Berlin Philharmonie in contrast to a Berlin Konzerthaus, a shoebox hall [Acoustics Australia]
Feb 2015: Our new article in Europhysics News discusses the non-linear perception of dynamics in concert halls, and popularizes the findings in PNAS article. Open access article is available in pdf format here: [Europhysics News]
Jan 2015: Three journal articles in preparation. Two papers discuss the emotional impact of concert hall acoustics.
Dec 2014: Interesting measurements with spatial car audio.
Sep 2014: Participated in the 55th AES conference in Helsinki Music Centre. A paper presented in the conference discussed the effect of amplitude panning in concert hall auralizations. The results from a listening test using loudspeakers and headphones suggest that the spectral brightness is reduced when spatial impulse responses are reproduced with amplitude panning followed by convolution, in comparison to nearest-loudspeaker reproduction.
Aug 2014: Summer vacations are mostly over, back at the desk planning and writing new studies…
Jun 2014: The PNAS article on orchestra dynamics and concert hall acoustics has been initially rather well received, and has gathered some international attention and discussion:
Huffington Post (by Prof. Trevor Cox)
Slipped Disc (by Normal Lebrecht)
Fast co Design (by Shaunacy Ferro)
YLE (by Katariina Hirvonen)
Mar 2014: An article describing the effects from musical dynamics in different shapes of concert halls was just published in PNAS (Proceedings of the National Academy of Science, USA). The study combines spectral effects in orchestra dynamics, directional hearing, and spatial analysis of concert hall acoustics. First of all, orchestra plays softly excites high frequencies only little. In contrast, with strong playing the high frequencies are emphasized more than low and middle frequencies. Second, the shape of the human head and ears modify the sound so that high frequencies are emphasized most when sound arrives from the sides. Last, shoebox-design halls are a general example of concert hall geometry that provides the listener with early reflections from the side walls. A combination of these three parts leads to results where the halls with strong lateral early reflections have the highest responsiveness to variations of orchestral dynamics.
Earlier studies have shown that early lateral reflections increase the overall perceived width and closeness of sound. Also, lateral reflections with high frequencies have been found to increase the subjective preference. Classical shoebox halls, such as Vienna Musikverein, Amsterdam Concertgebouw, and Berlin Konzerthaus, are often cited to be among the best concert halls. The current results suggest that lateral reflections, such as those found in these three halls, make the hall to respond more to nuances performed by the orchestra. As dynamic variation is one of the key elements in musical expressivity, halls with strong lateral reflection emphasize the dynamics, and therefore provide the audience with enhanced musical experience.
The article is available in the PNAS Early Edition before the final issue: http://www.pnas.org/content/early/2014/02/26/1319976111
Jan 2014: Two journal articles with me as a co-author were published in the first issue of JASA for 2014. One is an educational letter presenting the outcome of a recent data visualization course using spatial impulse responses as the source material. The students put up a fascinating set of visualizations form highly multi-dimensional data. Second is a statistical study by A. Kuusinen on the previous major listening test on Finnish concert halls. Originally the experiment was published in JASA by T. Lokki et al., and the follow-up article digs deeper into the connection between subjective preference and sensory profiles, and objective parameters. An interesting finding was noted between preference rating and high-frequency parameters.
Dec 2013: T. Lokki published an article about the results of the last major IVP listening tests on concert hall acoustics in Physics Today. The article was featured in the cover with a photograph from concert hall measurement by yours truly. Only later on, we have learnt that a featured cover article in Physics Today is in fact a rather coveted accomplishment…
Jun 2013: The ISRA2013 (International Symposium on Room Acoustics) in Toronto, Canada, was a success with a presentation introducting the Binaural Dynamic Responsiveness concept. In the end of the conference, we held a two-hour session with concert hall auralizations using a 16-channel sound system. Hear more here.
May 2013: Prof. Tapio Lokki, Dr. Sakari Tervo and yours truly held a two-hour tutorial about our research on concert hall acoustics in 134th AES convention in Rome.
Apr 2013: Last month’s list of the most downloaded articles in JASA featured again the time-frequency/spatiotemporal analysis article, this time at 7th place! Read the full article here. Dr. Philip Robinson’s article about diffuse reflections was also just published in JASA-EL.
Feb 2013: Google Scholar link added above.
Jan 2013: Journal article Analysis of concert hall acoustics via visualizations
of time-frequency and spatiotemporal responses has been published in Journal of Acoustical Society of America vol. 133(2). [Read the full article here]
Dec 2012: Journal article Analysis of concert hall acoustics via visualizations
of time-frequency and spatiotemporal responses has been accepted for publication in Journal of Acoustical Society of America. The article is due to appear in January 2013 issue. Short examples of the proposed techniques will be added here.
Oct 2012: Presentation in the Meeting of Acoustical Society of America, Kansas City, MI, USA.
Sept 2012: Journal article Temporal Difference in String Bowing of Symphony Orchestra Players has been published in Journal of New Music Research. The article presents the passive analysis of the mutual synchronization (or the lack of it) of string players in a symphony orchestra using video tracking. The article includes the validation of the tracking method, results of the temporal difference analysis between musicians, and an example study of music performance analysis. http://www.tandfonline.com/doi/abs/10.1080/09298215.2012.708048
May 2012: Matti Karjalainen award, Acoustical Society of Finland. For development of perceptual room acoustic evaluation methods, concert hall measurements, academic publications, and positive visibility in media (with Dr. Sakari Tervo, Dr. Philip Robinson, MSc. Antti Kuusinen, MSc. Aki Haapaniemi).
October 2011: Best student paper award, IEEE WASPAA 2011, New Paltz, NY, USA.
January 2011: Arup Acoustics Bursary Award, Arup Acoustics, Melbourne, Australia.