Horn loaded piezos are common in cheap PA systems (examples: https://www.parts-express.com/search?order=relevance:desc&keywords=piezo https://www.parts-express.

Horn loaded piezos are common in cheap PA systems (examples: https://www.parts-express.com/search?order=relevance:desc&keywords=piezo https://www.parts-express.com/search?order=relevance:desc&ke...). They typically work from about 3khz on up, which does involve the upper end of voice. Fidelity isn't great but the things are loud and hard to break for how cheap they are. No one in acoustics calls Q "quality" really. It's just "q" or people talk about underdamped vs overdamped, etc. If quality comes up, it's usually in the context of lower q designs being higher fidelity (eg, a subwoofer that's ~0.707 vs one that's say 1.2). What's most interesting about this new transducer is that it's physically thin, but acts as a monopole driver. That's cool and unique. They'll have to make some variations to dial in just how the geometry affects the response. Also, this driver as is would beam significant when made as large as some of the examples they talk about. But that's probably ok as the output is low enough you'd want to be in the near field anyhow.