Ping

Program notes

“Created by composer and researcher Chris Chafe and digital artist Greg Niemeyer, Ping is a site-specific sound installation that is an outgrowth of audio networking research at Stanford University’s Center for Computer Research in Music and Acoustics and interactive and graphic design experiments originating from the Stanford University Digital Art Center. Ping is a sonic adaptation of a network tool commonly used for timing data transmission over the Internet. As installed in the outdoor atrium of SFMOMA, Ping functions as a sonar-like detector whose echoes sound out the paths traversed by data flowing on the Internet. At any given moment, several sites are concurrently active, and the tones that are heard in Ping make audible the time lag that occurs while moving information from one site to another between networked computers.

Within the Ping environment, one can navigate through the network soundscape while overlooking San Francisco, a cityscape itself linked by the same networks that constitute the medium. Visitors to the installation can expand or change the list of available sites as well as influence the types of sound produced, choosing different projections of the instruments, musical scales, and speaker configurations in the surround-sound environment.

Current explorations pertaining to sound synthesis and Internet engineering are the foundation of the Ping installation. The research that led to this installation is, however, just one part of a larger effort to investigate the usefulness of audio for internetworking and, reciprocally, ways in which the Internet can abet audio. It is precisely this dialectic surrounding Ping that illustrates the increasingly common intersection of art and technical advancements, an interdisciplinary breeding ground where computer-based technology functions both as a stunning artistic medium and as a research tool.”

Goethe-Institut Inter Nationes

“Soundhenge” is an alternate title that the artists who created Ping have used to describe the physical form of their concurrent onsite installation in the San Francisco Museum of Art’s 010101: Art in Technological Times exhibition. The onsite version of Ping and this online version share the same musical engine; a piece of software created by composer, Chris Chafe.

Making music in real time from internet ping times can take many forms. “Pings” are short messages sent from the software to other computers whose identities are chosen by the viewer / listener (or from a database of default locations when no one is participating). Ping times measure “internet distance” by creating echoes. The short messages sent out by the software are returned as quickly as possible by the target machine. The elapsed time of this “travel” is recorded. Generally, this is only a number of milliseconds (about 3.0 – 650.0 msec at the SFMOMA installation). The lag time depends on a number of factors: traffic congestion, machine load, physical distance, number of relays, changing paths, etc. Machines anywhere in the world are fair game. Physically distant machines may have close or tighter echoes or vice versa. The interest derives from the behavior of ping sequences — sometimes they are steady and predictable, while at other times they can be quite dynamic.

The ping times are scaled to fit a more musical range of delays, which is about 0.25 – 50.0 msec. These are then rounded to the nearest point in a musical scale which is based on just intervals (harmonics like 1/3, 1/4, 2/5, etc.) played on an imaginary violin string. The stereo version of the piece has two strings (tuned in fifths, like a violin), and the “soundhenge” version has four pairs of strings. These are the root fundamentals of the harmonic scale and the transformed ping times determine the sounding length of a given string at that instant.

Fifty samples of banging sounds are used as sound sources in the music and were recorded from knocking against the aluminum speaker columns at SFMOMA. These percussive sounds become pitched when they excite a string (like plucking it). Sometimes, they play through with almost no string sound (not unlike like damping it with a hand), other times the string rings. The outcome depends on recent network behavior, represented in statistics like jitters (standard deviation), average and packet loss.

There is one string per audio channel and one “‘pinger’ thread” playing the string in the software. A target computer can be pinged simultaneously by multiple threads. In this version of the piece this happens by pairs. The online stereo ping has one target playing a pair of strings. At the onsite installation at SFMOMA, the eight channels correspond to a maximum of four targets at a time.

 – Chris Chafe