Halachic Source for no music during sefira

[dm123]

I'm losing interest in the conversation

PlatinumGuy, is this your way of changing the acapella conversation you're losing interest in to a conversation about slow music during 3 weeks/sfira? 

(Although TBH I think rikudin umecholos free music was mentioned somewhere upthread...)
Warning: clip contains [non dance inducing] music, duh.

[hocker]

Not following the whole conversation but IF recorded music is כלי שיר than it can't be defined as קול אשה... #JustSaying

[BCL]

https://olamot.net/shiur/%D7%9E%D7%95%D7%96%D7%99%D7%A7%D7%94-%D7%91%D7%A1%D7%A4%D7%99%D7%A8%D7%AA-%D7%94%D7%A2%D7%95%D7%9E%D7%A8-%D7%95%D7%99%D7%9E%D7%99-%D7%91%D7%99%D7%9F-%D7%94%D7%9E%D7%99%D7%A6%D7%A8%D7%99%D7%9D
Comprehensive shiur on the topic