Session with 4 singers, Trondheim, August 2017

Location: NTNU, Studio Olavshallen.

Date: August 28 2017

Participants:
Sissel Vera Pettersen, vocals
Ingrid Lode, vocals
Heidi Skjerve, vocals
Tone Åse, vocals

Øyvind Brandtsegg, processing
Andreas Bergsland, observer and video documentation
Thomas Henriksen, sound engineer
Rune Hoemsnes, sound engineer

We also had the NTNU documentation team (Martin Kristoffersen and Ola Røed) making a separate video recording of the session.

Session objective and focus:
We wanted to try out crossadaptive processing with similar instruments. Until this session, we had usually used it on a combination of two different instruments, leading to very different analysis conditions. The analysis methods reponds a bit differently to each instrument type, and they also each “trigger” the processing in particular manner. It was thought interesting to try some experiments under more “even” conditions. Using four singers and combining them in different duo configurations, we also saw the potential for gleaming personal expressive differences and approaches to the crossadaptive performance situation. This also allowed them to switch roles, i.e. performing under the processing condition where they previously had the modulating role. No attempt was made to exhaustively try every possible combination of roles and effects, we just wanted to try a variety of scenarios possible with the current resources. The situation proved interesting in so many ways, and further exploration of this situation would be neccessary to probe further the research potential herein.
In addition to the analyzer-modulator variant of crossadaptive processing, we also did several takes of live convolution and streaming convolution . This session was the very first performative exploration of streaming convolution.

We used a reverb (Valhalla) on one of the signals, and a custom granular reverb (partikkelverb) on the other. The crossadaptive mappings was first designed so that each of the signals could have a “prolongation” effect (larger size for the reverb, more time smearing for the granular effect). However, after the first take, it seemed that the time smearing for the granular effect was not so clearly perceived as a musical gesture. We then replaced the time smearing parameter of the granular effect with a “graininess” parameter (controlling grain duration). This setting was used for the remaining takes. We used transient density combined with amplitude to control the reverb size, where louder and faster singing would make the reverb shorter (smaller). We used dynamic range to control the time smearing parameter of the granular effect, and used transient density to control the grain size (faster singing makes the grains shorter).

Video digest of the session

Crossadaptive analyzer-modulator takes

Crossadaptive take 1: Heidi/Ingrid
Heidi has a reverb controlled by Ingrids amplitude and transient density
– louder and faster singing makes the reverb shorter
Ingrid has a time smearing effect.
– time is more slowed down when Heidi use a larger dynamic range

Crossadaptive take 2: Heidi/Sissel
Heidi has a reverb controlled by Sissels amplitude and transient density
– louder and faster singing makes the reverb shorter
Sissel has a granular effect.
– the effect is more grainy (shorter grain duration) when Heidi play with a higher transient density (faster)

Crossadaptive take 3: Sissel/Tone
Sissel has a reverb controlled by Tones amplitude and transient density
– louder and faster singing makes the reverb shorter
Tone has a granular effect.
– the effect is more grainy (shorter grain duration) when Sissel play with a higher transient density (faster)

Crossadaptive take 4: Tone/Ingrid
Ingrid has a reverb controlled by Tones amplitude and transient density
– louder and faster singing makes the reverb shorter
Tone has a granular effect.
– the effect is more grainy (shorter grain duration) when Ingrid play with a higher transient density (faster)

Crossadaptive take 5: Tone/Ingrid
Same settings as for take 4

Convolution

Doing live convolution with two singers was thought interesting for the same reasons as listed in the introduction, creating a controlled scenario with two similarly-featured signals. As vocal is in itself one of the richest instruments in terms of signal variation, it was also intersting to explore convolution wwith these instruments. We used the now familiar live convolution techniques, where one of the performers record an impulse response and the other plays through it. In addition, we explored streaming convolution , developed by Victor Lazzarini as part of this project. In streaming convolution, the two signals are treated even more equally that what is the case in live convolution. Streaming convolution simply convolves two circular buffers of a predetermined length, allowing both signals to have the exact same role in relation to the other. It also has a “freeze mode”, where updating of the buffer is suspended, allowing one or the other (or both) of the signals to be kept stationary as a filter for the other. This freezing was controlled by a physical pedal, in the same manner as we use a pedal to control IR sampling with live convolution. In some of the videos one can see the singers raising their hand, as a signal to the other that they are now freezing their filter. When the signal is not frozen (i.e. streaming), there is a practically indeterminate latency in the process as seen from the performer’s perspective. This stems from the fact that the input stream is segmented with respect to the filter length. Any feature recorded into the filter will have a position in the filter dependent on when it was recorded, and the perceived latency between an input impulse and the convolver output of course relies on where in the “impulse response” the most significant energy or transient can be found. The techical latency of the filter is still very low, but the perceived latency depends on the material.