The Aperion is a new musical instrument based on the principles of infinite sustain and acoustic resonance. The goal of the instrument is to encourage interaction and experimentation in a domain different from many conventional instruments.
The body of the instrument, built with Honduran Mahogany, takes inspiration from the Mexican Guitarrón. It consists of two large resonating chambers and a single electric bass string held in place between the bridge and the headstock. The body was designed to resonate at about 53Hz (or A1), emphasizing low frequencies.
The Aperion generates tones through the interaction of the vibrating string and body. The length and tension of the string can be varied by turning the machine heads, similar to conventional string instruments, or using a glass or metal slide. The string itself can be set into motion by plucking or striking, however the attack does not play as important a role in the timbre of the instrument as the sustain. The vibrating energy is transmitted to the top plate via the bridge and through the soundhole, which sets the body into vibration. The string’s vibration is sensed by an electric bass pickup, and is then amplified and fed to a moving coil loudspeaker that rests above a soundhole on the body itself. The loudspeaker remains in contact with the body, adding acoustic and mechanical energy to the system. The vibrating body transmits energy back to the string, and allows it to continue oscillation without decay, completing the feedback loop.
The Aperion has several modes of playability, each with distinct timbral characteristics and interesting envelope signatures. The most obvious and traditional style would be that of plucking and sliding, using a glass or metal slide. The slide changes the effective length of the string and allows for separate pitches to be plucked, strummed, or picked. Another and more sonically experimental playing style is that of moving the pickup along the track to extract varying harmonics from the string itself. The nodes and antinodes become exaggerated and clearly visible on the string. This is unique to the Aperion, considering most electric stringed instruments have fixed pickup locations, only allowing feedback to occur in a smaller harmonic range. Finally, an interesting discovery we found during construction was the way our lowpass and highpass filters in the power amplifier affected the resulting harmonics emanated from the Aperion. One can adjust these filters to extract high and low harmonics of the pitch to which the string is tuned.Tags: 2013, Acoustics, Georgia Tech, Music