I don't have a specific diagnosis or a solution, but the Altec Lansing speakers (which contain an audio amplifier) and serve my desktop machine are annoyingly vulnerable to interference from nearby radio frequency sources. My own HF and VHF amateur radio transmissions are the most obvious - these have been minimized by a dedicated grounding system for the radio equipment. However even parking the cordless telephone in its charging cradle in the wrong place (admittedly close to the 'control' speaker) will produce noises in the speakers obviously coming from that equipment.
Your problems suggests a similar set of circumstances. I'm reluctant to suggest a possible specific solution because the easiest one involves the fitting of a suppression capacitor to the switch of the offending lamp and this can be tricky and downright dangerous if not done correctly - mains voltages are probably involved.
The other possibility is to suppress interfering signal sources at the input to the amplifier within the speaker system - assuming it's that kind of arrangement. This again requires specific components and identification of where they are needed - difficult to direct without knowing the specifics of the equipment. In my observation it can also be difficult to get to the internals of some of the speaker systems around, my own being a good example.
As for the succession of booms noted in the original report; that is a real puzzle but seems to be linked somehow to the circuitry of that particular lamp, however I'm at a loss to explain it beyond that observation.
It's annoying that in this day and age, when problems like this can be predicted and usually prevented by the installation of quite low cost components in the production line of both 'transmitting' and especially 'receiving' equipment, that this isn't done.
