The noise is made by the flow of the gas - it's partially obstructed by something, most likely dirt. You should clean it thoroughly and check the gas pressure, it might have gotten too high for that lamp because the pressure regulator is slightly off.
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The noise is made by the flow of the gas - it's partially obstructed by something, most likely dirt. You should clean it thoroughly and check the gas pressure, it might have gotten too high for that lamp because the pressure regulator is slightly off.