Music On Yom Ha'atzma'ut

With Yom Ha'atzma'ut around the corner, I have received numerous email notices about related events, many from yeshivas and shuls.

Yom Ha'atzma'ut falls at a point in Sefirah where instrumental music is not permitted under any custom, whether you observe the prohibition from the begining until Lag B'Omer or from Rosh Chodesh until shortly before Shavuous.

Nevertheless, many of the Yom Ha'atzma'ut events of which I've been notified include live music. Even more interestingly, many of the events are being held on Saturday night or Sunday (before shkiyah), not Monday (the actual day of YH), yet still include music.

I don't really understand this. I'm not being sacrcastic or cynical. I simply don't know the halachic principles or rulings on which these musical events are relying. Especially with regard to those events being held on Erev Yom Ha'atzma'ut. If anyone does know I would be grateful for a heads up.

I do know that even raising this question in polite company is very politically incorrect and might subject me to accusations of being some kind of whacko anti-Zionist chareidi (which I'm not. At least the anti-Zionsit Chareidi part). I think this is one of those ideological issues that people don't give much thought to because of their love of and connection to Medinat Yisrael. The halachic issue just never enters the radar screen.