// our UGen patch
SinOsc ugh => dac;

while( true )
{
    // set frequency
    440 => ugh.freq;
    // let time pass
    .25::second => now;

    // set frequency
    880 => ugh.freq;
    // set gain
    .75 => ugh.gain;
    // let time pass
    .25::second => now;

    // set frequency
    1760 => ugh.freq;
    // set gain
    .5 => ugh.gain;
    // let time pass
    .5::second => now;
}