Latency is one of the main issues in telematic performances. The term refers to the amount of time the audio signals need to travel between different locations. As an indication of how crucial this is, a one-way latency above a threshold of 20-30 milliseconds makes it near-impossible to play together in a pulse based music environment.
However, if the system is fine tuned, if there is a stable internet connection and if the distance is not too big (not more than 500 kilometres), on might achieve such low latencies. With this, a Realistic Interaction Approach is possible.
With that said, latency is an integral part of the telematic performance medium, so why not play around with it!?
One option is the so-called Master-Slave-Approach. Here, one of the performers, the ‘master’, plays strictly in measure. The partner at the remote location, the ‘slave’, aligns according to the score, which sound almost perfect. However, the ‘master’ receives the signal with a delay, and as such, it will sound different at the master’s location.
Let us look at an example. The work Raindrops – a composition for flute and viola by the Hong Kong composer Lam Lai – was written specifically for a telematic environment.
Listening to the audio at the slave’s location – everything aligns well, as written in the score:
But listening to the audio at the master’s location, we can hear a high degree of latency, and a noticeable shift between the two parts:
With a one way latency of 120 milliseconds – typical for intercontinental performances – the resulting music sounds like this:
With a latency of 180 milliseconds, it sounds like this:
And here with a delay of 240 milliseconds:
It is of course also possible to swap the positions: in this case, the viola is the ‘master’:
Although the music does not correspond to what is written in the score, it nevertheless does not destroy musical significance, but rather, leaves it intact or even enhances it in an aesthetically appealing way.
There must be a meaningful relation between the tempo and the latency, to which musicians latch on to most often intuitively.