For large Ensemble

Duration ~23mins

'Kemp Echoes' (2013) was commissioned by AchtBrücken and the Ernst-von-Siemens-Stiftung to compose a piece which was to be performed along with Karlheinz Stockhausen’s compositions 'Mixtur', 'Mikrophonie II' and 'Gesang der Jünglinge'. 'Mixtur' is considered one of the first ever ensemble pieces with live-electronics. The sounds from the orchestra are picked up by microphones and ring modulated with sine tones, producing transformations of the natural timbres, microtonal pitch inflections, and—when the sine tone frequencies fall below about 16 Hz—rhythmic transformations. 'Kemp Echoes' is based on indexing acoustic sounds with a proximity to ring modulation without use of electronics : Ring modulations in woodwind instruments (particular multiphonics) and frequency modulations in complex spectra (bells, trills, brass idiophones and radio waves). Furthermore, ring modulation as a perceptive effect; perception of psychoacoustic phenomena, in particular difference tones. 

Some of Stockhausen’s electronic Music, which in its beginnings around 1950 dealt with the composition of sound spectra, marks the beginning of an epoch in which not only music but also the sounds themselves were composed. Stockhausen not only asked himself what music is and how it can be found, but also what sounds are from which his music originates. Frequently, he relied on the combination of electronic and instrumental or vocal music and transferred their respective characteristics to the other domain. An example of this is 'Mixtur' (1964): Four ring modulators (originally a radio devices to save energy in the transmission process) are used to create 'new timbral relationships' and 'new pitch relationships'.  What is ring modulation? If one technically multiplies two frequencies, one hears as a result their difference and their sum, i.e. f1 = 500 Hz and f2 = 800 Hz results in f3 = 300 Hz and f4 = 1300 Hz. In the text accompanying 'Mixtur' Stockhausen wrote: 'My systematic experiments with microphonation, filtering and ring-modulation of instrumental sounds first led to the work Mixtur in 1964. This gave a new direction to the artistic orientation of the studio work' Stockhausen had been the director of the studio for electronic music at WDR since 1963. For Stockhausen, there were two essential aspects of 'Mixtur': Firstly, the transformation of the familiar orchestral sound into a 'magical world of sound' led the listener to a completely new experience: an illusion between sound and sound by integrating new technologies. Secondly, the sidebands created by ring modulation create new overtone-series that do not occur in nature.
While working on 'Kemp Echoes' Schmickler wondered, if and how these technical process of a ring modulation, so crucial to early electronic music, could be done in the acoustic domain. He figured out that certain multiphonics, which can be played by woodwinds could produce these unnatural ring modulating spectra, by controlling the air flow through the instrument and the shape of the column.

The collaboration with the Ensemble Musikfabrik and particularly their oboist Peter Veale enabled him to examine these sounds more closely. In preparation for Kemp Echoes, Schmickler was ultimately able to prove that the phenomenon of ring modulation and thus the generation of new spectra (which supposedly do not occur in nature) can be generated on instruments alone, even without electronics. These ring modulating multiphonics appear several times in 'Kemp Echoes'. This is one of the correspondences to 'Mixtur'.

When Stockhausen spoke of nature, he meant the natural overtone series, frequencies which, as natural multiples of a fundamental tone, determine the timbral properties of the instruments and which are of decisive importance for our sense of consonance and dissonance. The theory of perception of musical intervals ranges from the Pythagoreans, organ builders of the Renaissance and Bach’s 'Well-Tempered Piano' to so-called 'spectral music' since the 1970s. A closer look at this history of tuning systems reveals some paradoxes and contradictions. Last but not least, Klarenz Barlow and William Sethares have been able to prove that our perception of consonance interacts strongly with the spectral characteristics of the sounds used: A chord will be perceived as more consonant when played by a particular instrument group, while it is perceived as less consonant by another instrument group.

However, it is not only the physical parameters that determine our perception of tones and music. We experience important practical applications of the findings of psychoacoustics daily in telecommunications, e.g. telephones and computers. For example, by developers taking advantage of the fact that the ear or our brain interprets a bass tone, for example by listening to a bass frequency for reasons of data compression or the missing size of a loudspeaker (i.e. residual tones or missing fundamental). So we actually perceive the missing tone, although it is not measurable. The brain generates the sound for our perception on the basis of a real measurable overtone spectrum. This is another conceptual consideration that is fundamental to 'Kemp Echoes': Discovering music and sound can also include rediscovery of the hearing. The second approach to researching and composing sounds for 'Kemp Echoes' thus relates to hearing itself. So-called 'difference tones', tones that only emerge in the ear as differences between two sounding tones, appear as an artefact just like the sidebands caused by ring modulation in Stockhausen’s 'Mixtur'. The title 'Kemp Echoes' refers to otoacoustic emissions, discovered by David Kemp in 1977, are sounds produced by the cochlea, the fluid-filled part of the inner ear that contains the sense organ of hearing. Emissions can be spontaneous, i.e. they can occur without prior stimulation, or they can be caused by a different sound stimulus. Evoked otoacoustic emissions last much longer than conventional echoes, their duration is also much longer than the duration of the original signal suggests, and finally the 'echo' itself is acoustically distinct from the stimulus.
Just as Stockhausen disregards the importance of technology as a meaningful experience for the listener, so does the use of electronics in 'Kemp Echoes': since technology is ubiquitous, it is about experiencing events. Stockhausen explores those areas of sounds in which the orchestra appears like electronic music. But also like a lawn mower, a vacuum cleaner, a transformer, everyday experiences of artificial or technical sounds are composed. We not only hear the music but also perceive at the same time how we hear music. A higher listening volume helps to perceive the processes of hearing in the ear, the difference tones more clearly. By moving her head a few centimetres, the listener hears these differences louder or less loudly.

'Kemp Echoes' was recorded live at Cologne Philharmonic on 05.12.2013 and conducted by Enno Poppe.