Most recently invented instrument

Jeff Beck was one of the early chapman stick innovators…

I don’t have much time for attributions of invenvtions such as the ‘pv instrument’ or the ‘airpole’ to the Blue Man Group. I was using homemade instruments, identical in principle, in primary school.

*pvc instrument

I’m not sure a synthesizer is a musical instrument, it’s a tone generating device. If the manner of controlling it counts than there may be questions because there are so many ways to trigger one but none are unique. Piano keyboard, guitar, wind instrument…

The Branching Corrugaphone
More on it here.

I think you’d have a hard time convincing a professional musician that his keyboard synthesizer is not a musical instrument.

By your definition, a sax isn’t an instrument either. It’s a tone generating device, controlled by the fingers.

New, but not really new, more “discovered recently,” how about the instruments popularized by Peter Schickele such as the tromboon, the horn & hardart, the double-reed music stand, and the pandemonium?

Well, the OP did ask for instruments “that [are] used regularly”.

Oh, and it’s called just plain “Hardart”, as in Concerto for Horn and…

Yep
Plus, playing the sax is more likely to get you laid than playing the accordion.

“I think you’d have a hard time convincing a professional musician that his keyboard synthesizer is not a musical instrument.”

What would this person be called professionally? A synthesizer player or a keyboard player/pianist?

Yes. Either. Generally if you say your instrument is “keyboards,” that includes the many sounds that are most easily controlled by a keyboard. Also called a programmer whether or not actual pressing down of black & white keys is needed. A piano player that does not dabble in electronic versions of anything is usually just a pianist or piano player.

At least that’s been my experience.

I play the synthesizer. I do not play the piano (unless you want to call it “playing the piano” when I use my MIDI keyboard to control a piano module). Why would I be called a “keyboard player/pianist”? The term for a synthesizer player is “synthesist.”

BTW, I cast a vote for the laptop computer, which is increasingly being used as an instrument in live performance.

The airpole is a bit of a stretch, I’ll grant you (although they have elevated the skill in playing significantly - I can’t find a good clip online, but I’ve seen them playing it as more than just a percussion device - they can actually vary the note it produces).

Anyway, I think you do the PVC instrument an injustice - it’s a fully playable musical instrument with a unique sound and works in a novel way - I think it makes an excellent candidate instrument to the OP’s question - I can’t see why it should be disqualified.

Did you really have something like this at primary school?

Nope. But we didn’t have a six-octave xylophone, nor a grand piano. The PVC instrument is an elaboration on much older traditional percussion instruments - take a look at the third one down here.

Using plastic tubes has expanded the possibilities of such instruments, sure. But it’s not a new invention.

Oh, that is almost exactly the same - I therefore withdraw the suggestion it’s a new instrument.

Interestingly, the bottom ends of the bamboo tubes are closed in that instrument - I would imagine this makes it less resonant and more percussive than the BMG’s PVC instrument, which has pipes open at both ends. Still, they’re clearly related.