The Country Music Hall of Fame in Nashville has these. Bad sound but the directionality works well. Want one of these in the bathroom so I can take a long shower and listen to podcasts without waking up my lovely wife.
They make a "speaker" for loud environments like trade shows or museums that are parabolic dishes. There's a speaker at the node and the dish reflects all of the sound back down into a collimated "beam". The ones I've specifically used were meant to be hung overhead so you only hear it when you step underneath. They were clear acrylic bowls that were 24"-30" diameter. It was mainly meant for delivering dialog/narration to a video playing without annoying the people working the booth. It was effective for the purpose
When this tech was new, there was hope that they could be used to produce good bass sounds. If you could produce good bass from such small speakers, we could probably handle the engineering behind de-directionalizing the sound, e.g., "bounce it off things".
Unfortunately, if it is possible, nobody seems to have figured out how to do it. The frequency response curve on these things are bad. Very bad. This has relegated them to small niches as a result.
I wouldn't guarantee that they would work with your podcasts; if any of them come from someone with a deep voice you could well lose the primaries and even some of the harmonics of the voice almost entirely. Trying to make out the resulting words over a shower is probably awful because the only frequencies these can play are going to cross awfully badly with the splattering of the water.
> Unfortunately, if it is possible, nobody seems to have figured out how to do it.
I'm not sure if you're referring to directional bass or to small speakers making decent bass. The former is fortunately a solved problem today - cardiod speakers (and their variants) do so, albeit DSP may be required/help.
For the latter, the issue is partly because you need to move double the air volume for every halvening of an ocatve. So going from 120hz to 30hz requires 4 times more moved air for same dBspl... but because of human ear (insensitivity), we need way more loudness at lower frequencies to sound "as loud" (Fletcher Munson curve or dbA weighting). Consequently it's kinda hard to get loud enough bass from small drivers (I can explain in more detail if you'd like). There's some interesting tech like Mayht speakers and Resonado but in its current form there are limitations.
It's still kind of the same issue. At the end of the day you need to move a lot of air for the bass. In theory some kind of air multiplier might allow these small-excursion ultrasonic speakers to do that, but unless there's a very good reason (or DARPA $$$) it's just more practical to do it conventionally.
Update: you are correct, the water-resistant bone conduction set works like a charm. And they won’t fall off. I’d say your solution is conservatively .5% what I would have paid for the less satisfying parametric array.
