Parametric Array speaker review?

[Richdw]

Hi All,

Parametric array speakers produce highly directional/localised audible sound via the intermodulation of two ultrasonic waves. This concept appears in a few niche or novelty applications, including research I'm involved with, but I don't see much mention of it in terms of general music listening applications. Recently I've seen recent articles referring to futuristic "headphones" with no earpieces that I have assumed, perhaps wrongly, may take advantage of this technology, and I wonder if the ASR community has any knowledge of this or other, extant or future, applications of parametric arrays in terms of music reproduction?

Here's a couple of wikipedia pages that give an overview of the technology:
https://en.wikipedia.org/wiki/Parametric_array
https://en.wikipedia.org/wiki/Sound_from_ultrasound

Here's an example of a commercially available device:
https://www.holosonics.com/audio-sp...MIsdaEtuWn7QIV1IBQBh13_woIEAAYASAAEgJYNPD_BwE

I'd be intrigued by any attempt to review some of the available devices, and I'm curious as to what future use the ASR community feels the technology may have.

Many thanks,
Rich

 

[peaknik]

This technology is quite old. I think the main limitation to the adoption is the low diffraction. The sound basically travels as a ray in a straight line more or less, and if something is between you and the transducer it would mostly block the sound. You can imagine how this would be a main barrier for adoption.
There are some military applications of this technology though, exactly for the same reasons

 

[Richdw]

Thanks for the reply @peaknik

Yes I agree it's an awkward concept to see working in a day-to-day setup! Do you think that the low diffraction, typically seen as a problem in the context of evenly distributing music in a lounge etc, could be utilised advantageously in certain pro or audiophile applications? Could it be used instead of a tweeter in a studio monitor to minimise the effects of any hf reflections present? Could this apply to other situations where hf reflections may cause issue, such as fixed listening positions in rooms where acoustic treatment to damp hf reflections is not desirable?

Any more thoughts on parametric arrays welcome!

 

[peaknik]

I have a degree in physics, but unfortunately I'm not an expert in acoustics So I can only speculate from the general principles.
What I can imagine is achievable is a phased array of ultrasonic transducers, which can track listeners in the room, and play different tracks for each, without disturbing the neighbours. From my limited understanding I cannot see any major roadblocks to implementing this in practice now, in terms of technology required. May be someone with more knowledge in the field can comment.

 

[Mnyb]

How conductive is air to ultrasound ? long distances is it linear ? some other problems ?

 

[tvrgeek]

Works as an anti-terrorist non-lethal weapon as you can inflict disabling pain from a distance. As far as music, how steady do you intend to hold your head? Or do you expect some sort of feedback tracking? An array of sensors around each ear and a super computer may be able to track sufficiently, but might as well wear headphones. A few products have been marketed, but all failed totally.

 

[anmpr1]

https://www.holosonics.com/audio-sp...MIsdaEtuWn7QIV1IBQBh13_woIEAAYASAAEgJYNPD_BwE : Audio Spotlight is a revolutionary directional audio technology that creates sound in a narrow beam, just like light.

Peter Walker figured out how to do that in the late fifties. (That's a joke, son!)

 

[peaknik]

How conductive is air to ultrasound ? long distances is it linear ? some other problems ?

I wouldn't imagine the loss changes much with frequency, but it can carry the waves much further due to lower diffraction. Same as bass vs. treble

 

[peaknik]

Works as an anti-terrorist non-lethal weapon as you can inflict disabling pain from a distance. As far as music, how steady do you intend to hold your head? Or do you expect some sort of feedback tracking? An array of sensors around each ear and a super computer may be able to track sufficiently, but might as well wear headphones. A few products have been marketed, but all failed totally.

You can track the listener using ultrasound as a radar. We already have this technology on our cars (parking sensors).

 

[tvrgeek]

Of course one thing we are missing, is ultrasound causes headaches.

Yes we can do crude tracking, but not with the precision to make interference waves demodulate. That is fractions of an inch. And you are assuming only one person. No a receiver that mashers the phase between the ears and then sends, BT maybe to the antenna to vary the phase might be closer to working.

 

[tvrgeek]

https://www.holosonics.com/audio-sp...MIsdaEtuWn7QIV1IBQBh13_woIEAAYASAAEgJYNPD_BwE : Audio Spotlight is a revolutionary directional audio technology that creates sound in a narrow beam, just like light.

Peter Walker figured out how to do that in the late fifties. (That's a joke, son!)

Now now, 57's weren't THAT bad.

 

[peaknik]

Of course one thing we are missing, is ultrasound causes headaches.

Yes we can do crude tracking, but not with the precision to make interference waves demodulate. That is fractions of an inch. And you are assuming only one person. No a receiver that mashers the phase between the ears and then sends, BT maybe to the antenna to vary the phase might be closer to working.

The health effects depend on the levels, exposure, and the frequency. Ultrasound in the medical setting is perfectly safe, but I wouldn't put my hand in an ultrasonic cleaner for example.
Personally I think it is simply not clear enough what problem does this method solve, while introducing a wide range of other issues to deal with.

 

[peaknik]

Phase arrays at the base frequency though are much more interesting. You can correct for the room geometry, bounce the sounds off the walls and ceiling for the 3D effect etc. I wonder why don't we see more products like Yamaha MusicCast YSP-5600