The Expanded Piano Context

Piano has always been the instrument of extreme musical flexibility, capable of delivering simple songs or complex polyphonic music performances over eight octaves and a wide range of dynamics. Throughout the past centuries, the piano has been also continuously reinvented as an instrument allowing extreme stylistic explorations: of frequencies and pitch, of dynamics and harmonies, of rhythms and articulations; also as an instrument for controlled musical expressiveness through a wide variety of playing techniques: from fast percussive staccato arpeggios to slow sustained lush chords.

One of the most radical reinventions of piano during the twentieth century has occurred through the “prepared” piano pieces of John Cage during the late 30s, works that created a novel canvas for polyrhythms and percussive timbres. Here this traditional instrument emerged as a new source for the experimental music of the 60s and subsequently during the next decades as the instrument bridging stylistically such experiments to past and emerging pianistic traditions, as the hybrid sonic vehicle for many of today’s significant music works.

In a parallel development, the twentieth century’s evolution of recording technology has modified our listening perspective of piano sounds. It is by now customary to hear piano reproduced through audio systems, away from its natural acoustic habitat of a concert hall. Within the recording medium, it is likely to appreciate soft, pianistic tingling notes hidden somewhere within a dense rock or jazz production, usually at the far left of the stereo field. In other cases, we come across the immense aural size of a good solo piano recording, likely extending the stereo perspective and utilizing the full frequency and dynamic range of our audio equipment. Such technological background has progressively shifted our collective hearing percept of piano sound away from the dimension of natural acoustic listening and into the domain of virtual electronic acoustic space. Through the recording medium, piano has been transformed within our subconsciousness as an instrument of immense aural and aesthetic possibilities.

The performance “Expanded Piano” by the composer Stavros Gasparatos pays homage to this ever-evolving aesthetic character of the instrument. Here the spectral and spatial piano properties are not merely extended via stylistic or recording and postproduction means. Instead, these aspects are expanded into the real physical space so that the listeners are immersed within a virtual new instrument whose aural size is only bounded by the extremities of the concert hall. This is now the piano heard through a sonic magnifying glass so that the listener embarks into an Alice in Wonderland-like acoustic journey.

The Expanded Piano Project

In essence, piano is a percussive instrument that transforms hammer activations into string vibrations, sympathetic coupling and inharmonicity and rich resonances of interconnected mechanical vibrating components, each having individual properties, which finally generate an elaborate acoustical radiation through the soundboard. The individual responses, especially those of the soundboard can be thus seen as filters shaping the timbre of the sound generated by the vibrating strings. The properties (responses) of these filters can be also measured via suitable excitation and recording. Such “piano filter” responses can be modeled with computer programs and constitute one element of the present piece by Gasparatos. Along with this, the technical concept of the expanding piano piece relies on the following elements:

  • The acoustic capturing of the piano sound via multiple microphones from different positions along its soundboard and strings
  • The direct capturing of soundboard vibrations through contact microphones
  • The triggering of electronic sounds from the normal playing action on the piano keyboard
  • The filtering and shaping of the direct piano sounds picked up by the diverse microphones through the programmed piano response filters
  • The acoustic projection into the space of the concert hall (“spatialization”) of these individual sound elements through their dynamic distribution to 24 loudspeakers arranged at 2 different height levels. The allocation of sound to loudspeakers above the heads of the audience offers an increased listener immersion being an emerging feature of current cinematic audio technology offered in selected movie theaters.

The performer-composer navigates through preselected “scenes” which consist of a set of parameters for all these options and combinations ultimately triggered from his playing action.

These technical extensions of the piano sound on one hand magnify, reinforce and expand the instrument’s natural timbral features; on the other hand these sounds are filtered through the “piano filters” and radiated through the multiple loudspeakers encircling the audience, spatially immersing the listener into otherwise unheard sonic details and combinations, a true re-invention of the piano.

—John Mourjopoulos, professor of Audio & Acoustic Technology Group, University of Patras, Greece