const byte speakerPin=9;
unsigned long lastPeriodStart;
const int onDuration=1000;
const int periodDuration=6000;
void setup()
{}
void loop()
{
if (millis()-lastPeriodStart>=periodDuration)
{
lastPeriodStart+=periodDuration;
tone(speakerPin,550, onDuration); // play 550 Hz tone in background for 'onDuration'
}
}