To study the acoustics of concert halls, an orchestra is needed that plays identically in each hall. Less than 15 years ago, I figured out how to do that. The idea was to build an orchestra of loudspeakers and play individually recorded instruments from different speakers. This is how our “loudspeaker orchestra,” 33 loudspeakers in carefully considered locations, was born. For the loudspeaker orchestra, we need to record the musicians one by one in an anechoic room and when I asked a few professional musicians and sound engineers for help, my idea was considered really weird; “You can’t just record a symphony orchestra like that”.

However, we pushed forward and we shoot a video in which one conductor was conducting one pianist. In the recordings of individual musicians they saw the conductor on a small screen and heard the piano track through open headphones. The recordings were a great success and are still in active use by the international scientific community, available for free for academic use. As part of the project, we were only able to record one musician / instrument and especially with the strings, we still had to come up with a solution to create a section from one single recording. This problem was solved too , the recording was done with many mics from different directions, each microphone signal is shifted a few Hertz out of tune, and finally both tempo and level are adjusted dynamically. The combination of these tricks makes one string instrument sound like a full section.

The acoustics of the concert halls themselves were recorded separately from each loudspeaker by measuring the so-called spatial impulse response. In this way, the placement of the instruments to locations on the stage can be done freely selected later and the orchestral recordings can be replaced with new ones if someone makes even better recordings. Today, even anechoic opera music recordings are available.

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In the spring of 2020, the world changed and the government forced people to stay at home as well as work remotely. For orchestral musicians, this is naturally quite a challenge and computer network delays are destroying remote ensemble playing. However, many orchestras came up with the same trick as we did in the past and suddenly our idea of a recording method became the mainstream of many professional orchestras. The first demo in Finland of the whole orchestra playing at home was made by Sinfonia Lahti, who recorded ”Finlandia” one by one:
[embedyt] https://www.youtube.com/watch?v=Sh1L-8T5hu0[/embedyt]

YouTube showed its strength and in less than three weeks the video has more than 115,000 views. (Some other projects have already over 2.5 million views at best!, links after the text) That’s a really big number in the field of classical music in such a short time! The video is great and it is interesting to peek into the homes of mucisians. On the video collection, one can sometimes even hear the acoustic conditions in which each player has played their own track, even though artificial reverberation has been added to the final result by sound engineer. But how would Sinfonia Lahti’s home musicians would sound if they would be playing at their own Sibelius Hall?

With the technology we have developed for concert hall acoustics studies, I can transfer this “home concert” to the musicians’ workplace at Sibelius Hall. We have Sibelius Hall’s spatial impulse responses measured and with the kind help of Sinfonia Lahti’s home concert production team, I got the individual tracks. I tuned the orchestra’s internal balance by ear, placed the players in the loudspeaker orchestra channels as shown below, and chose a good set for our measurements database from the main floor, line 9. Then the computer convolved (=multiplication of tho signals) the soundtracks and spatial impulse responses. The result was calculated into a 45-speaker surround sound system found in the premises of Aalto’s acoustics laboratory. This 45-channel file I then virtualized to be suitable for headphone listening (the process unfortunately deteriorates a bit the quality of spatial sound). The whole process allows the remotely working musicians to be moved to their own seats on the stage of the concert hall and you can listen to this “home concert” in real acoustics and enjoy the concert experience. You can listen to the result ( listen with headphones! ) here: ( Note, for some reason, Safari only plays for the first 2 minutes, but at least Chrome works until the end. )

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A few more ”home orchestra collections”, which I think are the bests so far in terms of both artistic and technical quality.

[embedyt]https://www.youtube.com/watch?v=jn27pQZnUnc[/embedyt]

[embedyt]https://www.youtube.com/watch?v=8FSyeyXpV_Q[/embedyt]

[embedyt]https://www.youtube.com/watch?v=Sj4pE_bgRQI[/embedyt]

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Finally, I had to link one more video to this end, even though the music genre is a quite different …