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1) If you are talking of light directly producing sound then it not possible without a transducing circuitry involved.
2) The sound that a tube light produces on low power is due to the choke thats made out of a induction coil. On low wattage you even observe the tube-light flicker this is due to the continuous rapid charging-discharging of the choke in order to keep the tube-light ON that makes it vibrate and produce sound. If the power falls futher low then the tube-light goes OFF.