Black-boxing the user: internet protocol over xylophone players (IPoXP)

We introduce IP over Xylophone Players (IPoXP), a novel Internet protocol between two computers using xylophone-based Arduino interfaces. In our implementation, human operators are situated within the lowest layer of the network, transmitting data between computers by striking designated keys. We discuss how IPoXP inverts the traditional mode of human-computer interaction, with a computer using the human as an interface to communicate with another computer.

💡 Research Summary

The paper “Black‑boxing the user: internet protocol over xylophone players (IPoXP)” introduces a whimsical yet technically grounded network protocol that places human performers at the lowest layer of the OSI model. Using two Arduino‑controlled xylophones, the system transmits IP packets between two Unix‑based laptops by having humans strike designated keys in response to LED cues. The implementation proceeds as follows: a computer generates an IP packet, encodes it as ASCII characters (SLIP style), and sends it over a USB serial link to a local Arduino. The Arduino translates each byte into a musical note, lights the corresponding LED on the xylophone, and the human operator—confined in a black box with limited visibility—observes the lit note and strikes the matching key. The key’s vibration is sensed by a piezo sensor on the remote xylophone, which the remote Arduino converts back into the original ASCII byte and forwards it to its laptop. Thus, the human operator functions as the physical transmission medium, embodying the OSI Layer 1 “bits” carrier.

The authors frame this inversion of the usual human‑computer interaction (HCI) as “black‑boxing the user”: the operator’s Umwelt is deliberately reduced so that they cannot comprehend the higher‑level meaning of their actions, mirroring how network devices are oblivious to the semantics of the data they ferry. By making the protocol’s encapsulation principle tangible—bits become visible LED flashes and audible xylophone tones—the work offers a concrete illustration of an abstract networking concept.

Related work includes RFC 1149 (IP over avian carriers) and the Bongo Project, both of which repurpose unconventional media for IP transmission. Unlike those, which rely on automated mechanisms (pigeons, solenoids), IPoXP requires a fully human‑driven physical layer, thereby pushing the boundary of socio‑technical assemblages.

Evaluation consisted of two public demonstrations at UC Berkeley’s Tangible User Interface showcase. Expert visitors quickly grasped the bandwidth (≈0.5 baud) and the protocol’s structure, while lay participants often fatigued before completing a single packet, highlighting the impracticality of a human‑based physical layer for real‑world networking. Audience feedback prompted design refinements: adding IP address labels, “sender/receiver” signage, and a Processing‑based animation that visualizes bits traveling between the laptops. These augmentations improved comprehension but did not resolve the fundamental speed and reliability constraints.

Future work proposes several enhancements: richer feedback (visual, auditory, haptic) when operators strike correct or incorrect keys; dynamic use of the xylophone’s unused black keys to encode additional IP‑header fields, thereby shifting human effort from header construction to payload transmission; and tighter integration of the projected animation with actual keystrokes. The authors also envision the installation as an educational artifact in museums (e.g., Computer History Museum) where its artistic and didactic value can be appreciated without the expectation of functional networking performance.

In conclusion, IPoXP demonstrates that the Internet’s core principle—encapsulation of bits over any medium—can be dramatized by turning humans into the transmission medium itself. The project serves both as a critique of the “black‑boxed” nature of network infrastructure and as a novel tangible interface that makes invisible protocol layers perceptible. While not a practical networking solution, it opens avenues for research on embodied networking, socio‑technical design, and pedagogical tools that expose low‑level network operations to non‑technical audiences.