When two projects share the same sensor

Across the projects in the ITP 30 Show, a small handful of sensors appear again and again, each time carrying the fingerprints of a different maker. The HC-SR04 ultrasonic distance sensor is one of those unassuming components — cheap, ubiquitous, and reliably inaccurate in interesting ways. Two pieces from this year's showcase reach for the same module and use it to ask very different questions about presence, space, and the bodies moving through them.

What makes these comparisons useful is not a verdict about which project is right. Both are responses to the same physical reality: an object that emits a chirp above the range of human hearing and times its echo. The sensor does not change. What changes is the artistic instinct around it, the choreography of inputs and outputs, and the cultural context each maker brings to the work.

For Australian viewers especially, the comparison feels grounded in familiar settings. Gallery-goers who queue outside the Powerhouse Museum in Ultimo on a humid Sydney afternoon, or wander through the laneway installations of Melbourne's ACMI-adjacent creative precinct, will recognise the spaces these projects were built to inhabit. The same hardware can read as gentle or jarring, intimate or institutional, depending on the room around it.

The component they start from

The HC-SR04 sends a 40-kilohertz burst from one transducer and listens for the return on another. At roughly thirty cents per unit, it has become a rite-of-passage part in physical computing classes, including those taught at ITP. Its range tops out near four metres, its minimum distance is about two centimetres, and its measurements drift noticeably with temperature and humidity — quirks that makers either tolerate, compensate for, or lean into as expressive features.

In both projects on display, the makers accept the drift as part of the aesthetic. Neither project hides the wobble. One uses it as a kind of breath; the other treats it as the soft static of a city at dusk. That decision shapes everything that follows, from enclosure design to printed documentation. Readers curious about how ITP work gets preserved and revisited over the years can explore the alumni digital archive, which traces how early prototypes evolve long after graduation.

Hush, a listening object

The first project, titled Hush, is a small ceramic vessel that sits on a low plinth and responds to the distance of anyone who approaches it. Inside, an HC-SR04 samples at roughly fifteen hertz, with each reading mapped to a slowly evolving chord played through a bone-conduction transducer hidden in the base. Stand a metre away and you hear a low hum; lean closer and a higher partial emerges; cup the vessel with both hands and the chord resolves into a single sustained note.

The maker describes the work as a study in polite attention — a comment, perhaps, on the social rules of shared indoor space. The vessel is deliberately not labelled beyond a small etched serial number, and the lack of instruction becomes part of the experience. Visitors from Melbourne's experimental music scene have already noted the similarity to works shown at the city's Now or Never festival, where ambient installations sit alongside pedestrian footpaths.

Pulse wall, a room-sized echo

The second piece, Pulse Wall, takes the same sensor and scales it up. Twelve HC-SR04s are arrayed in a row along a 3.6-metre wall, each mapped to a vertical strip of addressable LEDs. As visitors walk past the wall — for instance, while queuing during a Vivid Sydney after-dark session — their distance from each sensor shifts the brightness and hue of its corresponding strip. A group of friends striding together produces a coordinated wave; a solitary walker pulls a single column out of the dark.

Unlike Hush, this one is loud and social. The maker was explicit about wanting to turn a personal, intimate sensing into something observable by others. The reading itself is not the artwork; the artwork is the pattern that emerges when a dozen people interpret the same installation at once. Anyone wondering about the practical reality of installing such a piece can read a frank description of the gallery wall mounting process, which covers cabling, alignment, and the inevitable re-rigging the night before opening.

How setting shapes the reading

Both projects travel differently depending on where they are installed. Hush needs a quiet room and a low ceiling; Pulse Wall needs width and foot traffic. In a Sydney beachside pavilion during Sculpture by the Sea, Hush would lose its whisper to wind noise. In a Melbourne CBD basement, Pulse Wall would feel oppressive without enough bodies passing through. The makers acknowledge this in their project documentation, and neither piece is intended to be venue-agnostic.

This sensitivity to place echoes a recurring thread in the ITP 30 Show: that interactive work lives or dies on the specifics of the room. The same is true for the show itself, which exists online but traces its lineage to the physical hallways of NYU's department — a story visitors can read more about on the show background page.

What the comparison reveals

Side by side, the two projects make a quiet argument. The sensor is not the artwork; the framing is. Hush treats proximity as private, almost sacred, and asks the viewer to slow down. Pulse Wall treats proximity as choreography, asking viewers to move together. Both are right, both are possible, and both rely on a thirty-cent module from a Shenzhen warehouse.

For Australian makers considering their own builds, the takeaway is less about copying either approach and more about interrogating the defaults. What does it mean to use the cheapest, most common sensor available? Where can its limitations be turned into texture rather than noise? The ITP 30 Show is full of such questions waiting to be argued with — and the next project on the page is probably already doing it.

If these projects spark an idea, the ITP 30 Show invites you to look deeper, attend the upcoming online showcase, and consider submitting your own work — applications and RSVP details are available through the programme pages.