Music from the inner ear

Jacob Kirkegaard’s spectacular sound work ‘Labyrinthitis’ — originally commissioned by Medical Museion, first performed in the anatomical theatre at Medical Museion on Sunday, 2 September 2007, and again at the Museum of Jurassic Technology in Culver City, September 2008 — is now for sale on CD. You can order it from TouchShop. Read more below:

LABYRINTHITIS
Jacob Kirkegaard has turned his ears inwards: His new work LABYRINTHITIS is an interactive sound piece that consists entirely of sounds generated in the artist’s auditory organs – and will cause audible responses in those of the audience.
LABYRINTHITIS relies on a principle employed both in medical science and musical practice: When two frequencies at a certain ratio are played into the ear, additional vibrations in the inner ear will produce a third frequency. This frequency is generated by the ear itself: a so-called “distortion product otoacoustic emission” (DPOAE), also referred to in musicology as “Tartini tone”.
By arranging the tones from his ears in a composition and playing them to an audience, the artist evokes further distortion effects in the ears of his listeners. At first, each new tone can only be perceived “intersubjectively”: inside the head of each one in the audience. Kirkegaard artificially reproduces this tone and introduces it, “objectively”, into his composition. When combined with another distorting frequency, it will create another tone… until, step by step, a pattern of descending tonal structure emerges whose spiral form mirrors the composition of resonant spectra in the human cochlea.
Paradoxical as it may sound: we can listen to our own ears. The human hearing organ – still often perceived as a passive unidirectional medium – does not only receive sounds from the outside, it also generates its own sound from within itself. As a matter of fact, it can even be “played on”, just like an acoustic instrument.
Cellular vibrations: stimulating sound inside the body
Deep inside the labyrinth of the inner ear, in a spiral tube called ‘cochlea’, there are thousands of microscopic hair cells that function as sensory receptors. When sound enters the ear, they start vibrating in the watery liquid that surrounds them, like underwater piano strings. Depending on the amplitude and frequency of the sound waves entering ear, the movement of the hair cells will be strong enough to make their basilar membrane vibrate, too. Thus a new sound is produced: a faint tone that, if perceived consciously, might resemble a tinnitus. However, this tone is neither an echo nor just a psychoacoustic phenomenon – it can be measured, and even recorded with a microphone.
The scientific term for these sonic products of the inner ear is “otoacoustic emissions” (OAEs). There are different types of OAEs: Some are caused by random oscillations of the hair cells and arise spontaneously, others can be purposefully evoked by a specific acoustic stimulus that is sent into the ear from the outside. When the ear is stimulated simultaneously with two pure tones at a frequency of f1 and f2, and if f1 and f2 are at a ratio of 1:1.2, this stimulation will create a distortion effect in the cochlea: The ear itself will generate a third tone at a frequency f3, a so-called “distortion product otoacoustic emission” or DPOAE. (As DPOAEs will occur only when f1 and f2 are at a ratio of 1:1.2, the resulting f3 can be always be calculated from the frequencies of the two tones that evoked it: f3 = 2 f1 – f2. Consequently, DPOAEs will also always be at a deeper frequency than their stimuli.)
Under normal circumstances, it is impossible for an individual to listen directly to the distortion products of one’s own ears. But OAEs can be made audible with the help of sensitive microphones that are inserted into the outer auditory canal. (In medical science, this method is a standard procedure to evaluate the hearing capacities of newborn babies.) In June 2007, Jacob Kirkegaard had a range of DPOAEs recorded in an anechoic chamber at the Centre for Applied Hearing Research in Copenhagen, Denmark. Different tones on various frequency levels were sent into his ears through subminiature speakers. As the basilar membrane in the cochlea was stimulated, his ears started to generate tones. These tones, and the very process that generated them, serve as the basis of Labyrinthitis: an interactive composition and spatial-acoustic installation that involves both auditorium and audience.
Analogous structures: the creation and composition of triads
In musicology, (perceptible) DPOAEs are generally known as “cubical difference tones” or “Tartini tones” – after the Italian composer Guiseppe Tartini (1692-1770) who discovered that if you play two tones with a certain frequency ratio on the violin simultaneously, a third tone (“terzo suono”) appears. He even determined the frequency of this third tone: f3 = 2 f1 – f2. To this day, Tartini’s application of this acoustical phenomenon is useful for players of string instruments, since the tuning as well as the intonation of double-stops can best be judged by careful listening to the so-called difference tone.
Kirkegaard’s project combines Tartini’s musical insight with contemporary scientific knowledge about DPOAEs. In his composition, he starts off with two specific tones (both recorded from his ears) at a ratio of 1:1.2 and plays them at the same time. Stimulated by the distortion that these two tones will create in their own ears, the audience will be able to perceive a third tone. In a next step, Kirkegaard lets the two primary tones disappear and adds the third tone to the composition: It can now be heard “for real”, not just individually, in the room. Once this tone is established, a new tone is added in order to create, in combination with the earlier (third) tone, a further distortion in the same manner as before. By feeding more and more of these pairs of frequencies into the spiral structure of the ears of the audience, Kirkegaard goes on to create a descending tonal structure based on the resonant spectrums of the human cochlea itself. In short: While the audience is listening to the composition, their own ears will emit sounds in response to the sounds from the artists’ ears. At the same time, the room itself will turn into one big resonant labyrinth of sound.
Labyrinthitis: an inflammation causing systematic balance distortion
Medically speaking, severe interferences with the labyrinth of the inner ear can result in a syndrome of ailments called labyrinthitis. Labyrinthitis is a balance disorder; in addition to dizziness and other disturbances of equilibrium, patients may encounter a kind of temporary tinnitus: In response to the interference, ears and skull may start humming, singing, or even screaming. Kirkegaard’s composition is designed in such a way as to avoid any possible physiological damage to the aural system of his listeners. But his deliberate distortions can best be understood in analogy to the sickness – metaphorically speaking but also in rather literal sense: The symptoms might appear to be the same. As the title of the selected track – VERTIGO – suggests: to “suffer” from labyrinthitis is a spiralling, disorientating experience… pathologically speaking as well as aesthetically.
The metaphor of the spiralling labyrinth applies, in a more specific sense, to the location of the premiere performance of the piece. At the Medical Museion in Copenhagen, Kirkegaard chose to “play” the composition on a self-made instrument that he calls the Spiral Organ. It is a spatial installation consisting of 16 speakers placed in a downward spiral across the cupola ceiling of the museum’s old scientific auditorium. The Spiral Organ is more than just an obvious reference to the twisted tube form of the cochlea: It offers an artistic reconstruction of the processes in the inner ear. As a simplified macro model of a complex miniature structure, it invites the audience to experience the ear as an active organ – an instrument – both in a physical and in a musical sense.
LABYRINTHITIS was created as a non-exclusive commissioned work for The Medical Museion in Copenhagen and was first presented at the international conference “Art and Biomedicine: Beyond the Body” on September 2nd, 2007. Curator Stine Hebert initiated the collaboration between Jacob Kirkegaard and The Medical Museion. The Spiral Organ was designed by Bjørn Staal Dinesen after an idea of Jacob Kirkegaard.