Combustion Pulsation and Noise
All commercial burner systems make some amount of noise, starting with the white noise generated by a gas fired home heater. Systems firing millions of BTUs produce correspondingly louder noise. Improper design can generate lower frequency noise, sometimes at very high decibel levels. Such noise is usually accompanied by visible pressure fluctuations in the furnace or boiler. If a furnace is involved, and is designed (accidentally, of course) to resonate at a critical frequency, then much higher frequency noise is possible.
For more detail, see the fact sheet.