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On my music and beyond: Orchestration Balancer

by Uljas Pulkkis

"I am currently exploring ways of ensuring the audibility of a specific instrument in orchestral texture before rehearsals even begin." This column is part of the series "On my music and beyond", where composers and other music makers write about their music.

Orchestral music has fascinated me ever since I was a child, particularly the kind where there is a soloist with an orchestra. My earliest musical memory is of a concert at Finlandia Hall where I heard Emil Gilels playing Tchaikovsky’s Piano Concerto no. 1. I was about seven years old. Recalling that occasion, I find that I was struck not so much by the colours of the orchestra as such as by the sound of the piano amplified by the orchestra. My impression of the concerto was that the sound of the piano was supernaturally rich, penetrating, deep, full and embracing, which of course was due to the fact that the piano and the orchestra worked together in seamless cooperation.

Later, I had the same experience in Wagner operas, where a singer can fill an entire opera auditorium when appropriately supported by the orchestra. I came to discover in listening to orchestral repertoire that orchestral music does not always work like this: orchestration can have many functions, but it was the acoustic amplification function that stayed with me and has fascinated me for decades. 

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The reason I became a composer was the desire to write music where the sound of a soloist is astonishingly amplified through orchestration. To achieve this, I experimented with a variety of approaches in the early stages of my career: soloists of different kinds, various compositional techniques, various instrumentations. And did it work? Sometimes it did, sometimes not so much.

The best way to achieve a rich and full sound is to write for instruments in their ideal ranges and to write pitches that reinforce the overtones of a particular frequency, i.e. that amplify the natural resonance of a tone. This will at least guarantee that the sound carries. But what about specifically amplifying the sound of a soloist?

The problem with a deep and thick orchestral sound is that it mercilessly overwhelms every softer sound like an ocean wave. Even the scintillating and penetrating timbre of the piano can be overwhelmed by an orchestra. In cello concertos and violin concertos, even those in the core repertoire, one can find moments where it is difficult to make out the soloist. And in opera it often happens that a singer cannot be heard over the orchestra, even though the composer certainly intended it. So to generalise: how can we be sure that we will hear the instrument we want to hear in a particular orchestrated passage?

How to make a particular instrument audible is an issue not only for situations with a soloist and orchestra but for orchestration in general. When I write orchestral music, I do want the sounds to blend together, but equally I want the one really important thing to stand out. This can be done by thinning out the surrounding orchestration to ensure that the key line will be heard, but that means compromising on sonority. Audibility can of course also be ensured by scoring the line for an instrument with a lot of energy, such as a trombone or trumpet. But what if the music calls for a different kind of instrumentation?

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To create an orchestral work yet avoid the aforementioned concerns, I wrote a piece called Virtual Piano Concerto in 2014. The work is for piano and a loudspeaker orchestra. The loudspeakers are to be placed in the form of a symphony orchestra in performance so that the part of each musician is played through a separate speaker. The speakers for the premiere were kindly loaned by the Finnish audio company Genelec (see also FMQ article here), and assistance in the placement was provided by Professor of Acoustics Tapio Lokki and researcher Jukka Pätynen (see also Tapio Lokki's column here). There were small speakers for small instruments such as flutes, medium-sized speakers for cellos and a huge bass speaker for timpani.

I created the work as a sound file with dozens of separate tracks containing music played on actual acoustic instruments that is then played back through the speakers. The piano soloist is also the conductor (Emil Holmström at the premiere), as he controls the loudspeaker orchestra with foot pedals while playing his part. The acoustics of the orchestra are not predetermined: the instruments were recorded anechoically, and the acoustics are created by the space in which the work is performed, just as with a real orchestra.

Using a loudspeaker orchestra gave me full control over which instrument can be heard at any given time. The volume of any instrument can be turned up or down, even in real time during the performance. I discovered in the performance that adjusting volume is not the best way to ensure audibility. Instead, eliminating the frequency range of the piano part from the orchestra allowed me to keep the volume of both the piano and the orchestra up without any balance issues.

If I discover at rehearsals for an acoustic orchestral work of mine that I cannot hear an instrument I want to hear, I ask the conductor to tell everyone else to play more quietly. This would perhaps not be necessary if the frequency range of the instrument in question were not otherwise occupied. After the loudspeaker orchestra project, it occurred to me to consider whether this business of dedicated frequency ranges could be applied in acoustic orchestration as well.

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I am currently exploring ways of ensuring the audibility of a specific instrument in orchestral texture before rehearsals even begin. I am working on an artistically oriented doctorate on this topic at the Sibelius Academy while also studying acoustics at Aalto University. The best way to study the opacity and timbre parameters of a complex orchestration situation is to compile the data in easily searchable form, i.e. in a database. This database contains a huge amount of information on things such as the focus points of instrument spectra, the opacity of instruments to critical bandwidths in our hearing spectrum and tonal colour, all encoded using Mel Frequency Cepstral Coefficients. Compiling this database forms part of my doctorate.

As an adjunct to the database, I am coding a web-based application in Java where the user can load a page of a score and specify which instrument to examine in terms of audibility. The application compares the score to the database and pinpoints the instruments that compromise audibility. The range or dynamics of the obscuring instrument can be individually adjusted in the score using the application. This resolves the audibility issue without changing the intensity of the sound, achieving the ideal of acoustic amplification that I have admired since childhood. The working title of the application is Orchestration Balancer.

Uljas Pulkkis at Music Finland's Composers and Repertoire website.

Translation: Jaakko Mäntyjärvi
Featured photo: Saara Vuorjoki / Music Finland