SonicHoop

Aerial hoops

An aerial hoop, also known as a lyra, an aerial ring or a cerceau, is a circular steel hoop that is suspended from a height, using specialized rigging straps and a combination of carabiners and swivels. The word lyra comes from the Latin word for "lyre", which is a harp-like musical instrument that has a circular shape. The first recorded use of an aerial hoop was by a performer called "Caedo" in 1893. Cirque du Soleil introduced the now-familiar circular form, and popularized it as an aerial art form in its shows in the mid-20th century. Now aerial hoop has transcended its stereotypical role as part of a circus act into special fitness programs offered in dance studios and gyms worldwide.

Overall Architecture

SonicHoop system overview: Four Arduino MPR121 capacitive touch sensors detect touch events from 42 electrodes covering the whole hoop. The data is gathered by a Bitalino R-IoT and sent to Max/MSP via wifi. SonicHoop works as a standalone device, requiring no extra equipment for the aerialists to wear.

SonicHoop Hardware

(a) 42 electrodes on SonicHoop using (b) four MPR121 capacitive touch sensors and a Bitalino R-IoT. (c) Electrodes are 1.5cm wide and 4.5cm apart, and are connected to Arduino sensors using (d) ultra thin copper wires (0.1mm).

SonicHoop Software

Max/MSP receives the raw touch data, a list of 42 floats every 15 milliseconds, smooths it using a moving average filter and detects touch events (touch or release) using a step detection process, and generates sound accordingly. The two filters are implemented using Pipo and sound is generated using CataRT and Ableton Live.

Touch-to-Sound Latency

Touch-to-sound latency of SonicHoop: (1) touch on the hoop; (2) Max/MSP receives the raw sensor data; (3) a touch event is triggered after applying 2 filters; (4) a sound is generated accordingly in Max/MSP and (5) the sound is output from the laptop’s speakers. (1)–(2): 10 ms, (2)–(3): 82 ms, (3)–(4): 8 ms, (4)–(5): 10 ms. Total latency (1)–(5): 110ms.

Sensitivity to Texitles

Sensitivity to 5 different textiles: SonicHoop can detect touch events when applying up to 1.5mm of 100% cotton, up to 0.8mm of 100% polyester, up to 1.4mm of 90% cotton with 10% elastane, and up to 0.6mm of 75% cotton with 25% elastane and 85% polyester with 15% elastane. Sensitivity is calculated using the difference between sensor standby raw value (34) and the decreased value when touch is applied, e.g. direct skin contact = 26.5, therefore sensitivity = 7.5.

Sound Design

We developed three sonification strategies that vary the character of the sound, choice of sequence and layering of loops. Each sound design is distinct from the others in terms of musical style and composition strategy.