The customs of what can and cannot be done during the "Three Weeks" varies somewhat from community to community. Even on the issue of music alone there is a variety of customs - not to listen to live music, not to listen to any music including recorded music, acapella being ok or not, etc.

The religious radio stations, at least here in Israel, all take the position of playing almost no music at all, with some exception made for acapella that is low-key.

Someone from the USA asked Rav Meir Mazuz if haredi radio stations in the USA could play music during the Three Weeks. He explained his question as being based on an assumption that if the Jewish stations are not playing music, there will be many listeners who would turn the dial to a non-Jewish radio station and end up listening to secular music. And, he added, the Haredi music gives chizzuk to many people.

Rav Mazuz responded with a psak that they can play regular music during the Three Weeks in order to prevent the listeners from switching to secular stations playing secular music.

Rav Mazuz did qualify it as saying they could play soft music, serious music, and not loud, energetic music. Rav Mazuz compared it to the allowance to sell meat even during the week of Tisha b'Av so that people won't chas vshalom eat treif meat instead.

Rav Mazuz also stated that he himself listens to music on Friday afternoons in order to bring Shabbos in in a state of happiness and joy.
source: Srugim

I don't know if they are doing this in the USA on the haredi radio stations, but here in Israel this would not fly.