# Directional Speakers

#### djsfantasi

Joined Apr 11, 2010
8,447
I split my response to @Ya’akov in “Line Array Directional Sound”. Ya’akov directed a response to me in that response.

My application requires projecting sound to an approximately 25 sq ft area in which up to 5-6 people may occupy (there will be two such areas adjacent to each other). Everyone within this space must hear the sound. There will be a dozen or so such areas all contained within a larger 2,500 sq.ft. open space. When a person is in one of the many 25 sq.ft. spaces, he should hear the sound for that area. He should not hear anything from the other spaces.

I have contacted Holosonics with regard to this application, met with the engineers and got a product demo. I have also negotiated a significant discount.

But even then, their product for my application (20-24 speakers) is a significant investment. Most of us know that sometimes we want good and inexpensive, but that’s not always possible.

Ya’akov posted the following video.

I forgot about the possibility of parametric speakers using ultrasonics. I also think it is possible to combine a line array and para metric speaker techniques to create an electronically steerable array since an ordinary parametric speaker has a fixed direction. The video below is just one of many resources for home builds.

@djsfantasi is this something like what you were looking for?
I have two questions, Ya’akov (and others).

The author says the audio quality is due to his smartphone (as anyone whose tried to record a live concert can attest). My audio will primarily be voice, with occasional music. Will the quality be good enough so listeners can understand the voices?

Secondly, there is a section of the video where it shows a nearby person hearing the voice “bounced” off his neighbor. First, the perception of direction is important and this could affect quality. Second, when there are 5-6 people under each speaker, won’t sound be a muddy perception of multiple reflections. And where there are two adjacent “speakers”, wouldn’t these reflections ruin the direction perceived?

#### MisterBill2

Joined Jan 23, 2018
12,704
My inclination is to not trust anything that I see presented on you tube. It might be correct, or it may not be correct. Possibly some presentations can be verified independently. But if anything can't be verified from a source other than you tube I regard it as not to be trusted.

#### LowQCab

Joined Nov 6, 2012
2,342
It aint gonna happen like You describe without a 10-foot-long Folded-Horn overhead.

It's fairly easy, ( and much smaller ), to make sounds above ~1khz very directional,
but below that Frequency, the Sound-Waves start getting very LOONNGGGG,
and controlling their direction of dispersion gets even more difficult the lower the Frequency goes.

That's just the way Sound works.

Sounds below around 100hz are virtually omni-directional, and extremely difficult to control.
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#### djsfantasi

Joined Apr 11, 2010
8,447
It aint gonna happen like You describe without a 10-foot-long Folded-Horn overhead.

It's fairly easy, ( and much smaller ), to make sounds above ~1khz very directional,
but below that Frequency, the Sound-Waves start getting very LOONNGGGG,
and controlling their direction of dispersion gets even more difficult the lower the Frequency goes.

That's just the way Sound works.

Sounds below around 100hz are virtually omni-directional, and extremely difficult to control.
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What “ain’t gonna happen”? You weren’t specific. I have a commercial solution based on ultrasonic technology. I was wondering if there’s an alternative.

As I stated,
I have contacted Holosonics with regard to this application, met with the engineers and got a product demo.
So what do you mean?

#### LowQCab

Joined Nov 6, 2012
2,342
What is the Frequency-Response of the Holosonics solution ?, and is it actually acceptable ?
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#### MisterBill2

Joined Jan 23, 2018
12,704
One more thing is the assumption that all of the people have perfect hearing. That is not really very probable.

#### Tonyr1084

Joined Sep 24, 2015
6,961
Saw it on the Henry Ford's Innovation Nation TV show. The speaker was demo'd to one of the people on the show where the young woman stood approximately 30 feet away from the speaker. When she stood in the right place she could hear music. When she stepped 3 feet to either side she couldn't hear anything from that speaker. Though that was pretty cool, but they didn't explain enough about how it worked for me to glean anything useful. I guess that was deliberate to protect propriety rights.

Is it possible? From what I've seen (not on YT) I have to say apparently it is.

#### LowQCab

Joined Nov 6, 2012
2,342
It's very doable, but HUGE, and with extremely limited Frequency-Response.
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#### MisterBill2

Joined Jan 23, 2018
12,704
There is a "whispering galley" effect that involves reflection for dispersion and collection, (Refocusing), which is not new by any means. BUT it takes a fair sized reflector. The curved speaker array is an alternate scheme for a similar effect. A parabolic microphone uses the same effect. So do satellite receive antennas. Nothing new there. But it works for shorter wavelengths and that is a serious limitation. Not much bass with a small reflector.

#### djsfantasi

Joined Apr 11, 2010
8,447
Saw it on the Henry Ford's Innovation Nation TV show. The speaker was demo'd to one of the people on the show where the young woman stood approximately 30 feet away from the speaker. When she stood in the right place she could hear music. When she stepped 3 feet to either side she couldn't hear anything from that speaker. Though that was pretty cool, but they didn't explain enough about how it worked for me to glean anything useful. I guess that was deliberate to protect propriety rights.

Is it possible? From what I've seen (not on YT) I have to say apparently it is.
That’s where I saw it as well. I had an immediate application and followed up. The company is in a Boston suburb, so as I’ve said, I made an appointment. I spent an afternoon with an engineer and a sales rep. They have many models, each with specific features and have continued to improve the technology. They have a built in amplifier and can source sound from a SD drive, line-in input and Bluetooth.

@LowQCab - you keep mentioning limited frequency response… but don’t define what you mean by limited. If you wanted to project an orchestra to one person, you might be right. But do all applications require that level of frequency response? And are you familiar with the Holosonics X-series and their improved specs?

The speakers are optimized for speech and for that application, they excel. And for a broad range of audio, they excel as well. Their website (which I urge you to check out) describes how the recent models have a much broader frequency response, has a case study of a museum application for demonstrating various styles of music, described improved volume by 2X, has 10x the directivity, summarizes the ultrasonic technology and more.

They work. They work well. And they’re always improving.

I started this thread to see if there was a practical alternative to Holosonics. It has devolved into bashing a product without understanding it. Instead of bashing Holosonics, can we focus on my original question?

#### LowQCab

Joined Nov 6, 2012
2,342
"" But do all applications require that level of frequency response?
And are you familiar with the Holosonics X-series and their improved specs? ""

There are no standard "Specs" anywhere on their website.
Frequency-Response or Amplifier-Output-Power are both conspicuously missing.
And no prices either.

Frequency-Response ............
200hz is just fine for "PA" work, ( Voice-only ).
It is completely unacceptable for Music-Reproduction.

I would be willing to bet serious Money that there is
ZERO proprietary technology being used in these Panels.
They are like ~$350.oo Speaker-Cables, pretty, but the claims are total BS. And further, I'll bet that the "starting-price" is close to ~$800.oo per panel.

Here is some stuff I collected from their website .................

"" WHAT IS THE FREQUENCY RESPONSE OF THE SYSTEM? ""

"" Inherent in the use of ultrasound to reproduce audio is a
tradeoff between maximum output level and low frequency response. ""
"Maximum Output Level" Specifications are no where to be found on the entire website,
neither are any Frequency-Response-Graphs to be found.

"" This is controllable on every unit using the EQ and Preset features.
A rough guideline for practical frequency response is about
200 to 400 Hz at the lower limit to 20 kHz at the upper end. ""
That's an entire Octave of Low-End Frequency-Response "Range",
what does this mean ???
At what specific Frequency does the Output drop by 3db ?,
( which is the standardized way everybody else in the World measures Frequency-Response ),
( except of course China, where they multiply every specification by at least 10 times ).

"" The AS-24i offers the deepest low frequency response and
strongest output of all Audio Spotlight models,
and is an excellent choice when rich, full sound quality is important. ""
Sorry, a 200hz lower limit is not "Rich and Full" .......
This is nothing but advertising blather.
How many db@1-Meter and 1-Watt of Input-Power is "strongest-output" ?????

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Panel-Speakers ......
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Tech-Ingredients is cramming over ~100-Watts of Power into their Panels
to get a reasonable listening volume.
Most likely, Audio-Spotlight is using a small, maybe 10-Watt, Digital-Amp,
which is not going to cut through very much external-noise.

The Tech-Ingredients Panels still have to use a Sub-Woofer to
have any type of Low-End Frequency-Response, even though they have twice as much surface area.
They point-out the Sub-Woofer in the Video.

The Largest Audio-Spotlight-Panels,
( which I must assume are the ones that supposedly can reach "as-low-as" ~200hz ),
are 24" X 24",
this is 8-feet in circumference,
which equates to a Wavelength of around ~140hz,
( by using a "rule-of-thumb" for designing Horn-Loaded Loudspeakers ),
this means that by roughly 280hz the Audio-Spotlight Speakers are starting to loose their "directivity",
so they would have to CHOP the Frequency-Response
extremely hard, before reaching ~140hz, to maintain any sort of directivity claims.
And, the Audio-Spotlight Panels WILL loose directivity as
the Frequencies they are asked to produce get lower.

An ordinary Mineral "Ceiling-Tile", ( like the ones in every business office ),
will do the exact same thing when an "Exciter" is attached to it.
https://www.parts-express.com/Dayton-Audio-DAEX58FP-Flat-Pack-58mm-Exciter-25W-8-Ohm-295-210

Build your own Panels for ~$20.oo bucks ............... . . . #### Attachments • 153.7 KB Views: 2 Thread Starter #### djsfantasi Joined Apr 11, 2010 8,447 "" But do all applications require that level of frequency response? And are you familiar with the Holosonics X-series and their improved specs? "" There are no standard "Specs" anywhere on their website. Frequency-Response or Amplifier-Output-Power are both conspicuously missing. And no prices either. Frequency-Response ............ 200hz is just fine for "PA" work, ( Voice-only ). It is completely unacceptable for Music-Reproduction. I would be willing to bet serious Money that there is ZERO proprietary technology being used in these Panels. They are like ~$350.oo Speaker-Cables, pretty, but the claims are total BS.
And further, I'll bet that the "starting-price" is close to ~$800.oo per panel. Here is some stuff I collected from their website ................. "" WHAT IS THE FREQUENCY RESPONSE OF THE SYSTEM? "" "" Inherent in the use of ultrasound to reproduce audio is a tradeoff between maximum output level and low frequency response. "" "Maximum Output Level" Specifications are no where to be found on the entire website, neither are any Frequency-Response-Graphs to be found. "" This is controllable on every unit using the EQ and Preset features. A rough guideline for practical frequency response is about 200 to 400 Hz at the lower limit to 20 kHz at the upper end. "" That's an entire Octave of Low-End Frequency-Response "Range", what does this mean ??? At what specific Frequency does the Output drop by 3db ?, ( which is the standardized way everybody else in the World measures Frequency-Response ), ( except of course China, where they multiply every specification by at least 10 times ). "" The AS-24i offers the deepest low frequency response and strongest output of all Audio Spotlight models, and is an excellent choice when rich, full sound quality is important. "" Sorry, a 200hz lower limit is not "Rich and Full" ....... This is nothing but advertising blather. How many db@1-Meter and 1-Watt of Input-Power is "strongest-output" ????? ---------------------------------------------------------------------------------------------- Tech-Ingredients YouTube Channel ...... Panel-Speakers ...... ---------------------------------------------------------------------------------------------- Tech-Ingredients is cramming over ~100-Watts of Power into their Panels to get a reasonable listening volume. Most likely, Audio-Spotlight is using a small, maybe 10-Watt, Digital-Amp, which is not going to cut through very much external-noise. The Tech-Ingredients Panels still have to use a Sub-Woofer to have any type of Low-End Frequency-Response, even though they have twice as much surface area. They point-out the Sub-Woofer in the Video. The Largest Audio-Spotlight-Panels, ( which I must assume are the ones that supposedly can reach "as-low-as" ~200hz ), are 24" X 24", this is 8-feet in circumference, which equates to a Wavelength of around ~140hz, ( by using a "rule-of-thumb" for designing Horn-Loaded Loudspeakers ), this means that by roughly 280hz the Audio-Spotlight Speakers are starting to loose their "directivity", so they would have to CHOP the Frequency-Response extremely hard, before reaching ~140hz, to maintain any sort of directivity claims. And, the Audio-Spotlight Panels WILL loose directivity as the Frequencies they are asked to produce get lower. An ordinary Mineral "Ceiling-Tile", ( like the ones in every business office ), will do the exact same thing when an "Exciter" is attached to it. https://www.parts-express.com/Dayton-Audio-DAEX58FP-Flat-Pack-58mm-Exciter-25W-8-Ohm-295-210 Build your own Panels for ~$20.oo bucks ...............
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You are missing the point that these are not acoustic speakers. The device itself cannot be compared to a speaker.

And the sound from a Ceiling Tile/Exciter combination will bleed outside a four square meter area. While the Holosonics can NOT be heard outside the same area. Are you telling me that 24 of the CT/E speakers, all playing different audio in an open warehouse space, won’t result in a muddy mess? The Holosonics won’t!

It uses ultrasonic technology first developed in Germany. Holosonics is now the worlds premier developer of ultrasonic audio technology. Did you read the articles on the “Technology” page?

A four square foot panel provided enough volume at 12 feet to be heard over Boston highway traffic. And over people talking in the same room during my demo. On the Henry Ford's Innovation Nation TV show, they demonstrated an early Audio Spotlight to the reporter outside in a city park. A lot of ambient noise there. And she could hear the sound clearly at a distance of 20 feet and ONLY within a few feet of the device’s center

I understand your disbelief. But a product demo was very instructive.

Not everyone is an audiophile. My application is maybe 95% speech and 5% background music. Holosonics target market is not concerned with audiophile quality. These devices would NOT and are NOT used for serious music reproduction.

You can’t judge a product by expectations that it wasn’t designed to address. It’s like comparing the speed of a Honda Civic to Bullet Train because they’re both used for transportation.

So far, you’ve convinced me that there is NO other solution.

I’m still willing to listen to other member’s opinions.

#### MisterBill2

Joined Jan 23, 2018
12,704
I am certainly not bashing any product. But certainly something producing those results is neither simple, nor would it be cheap.
Probably it would not be simple, cheap, or easy to duplicate, either.

#### djsfantasi

Joined Apr 11, 2010
8,447
I am certainly not bashing any product. But certainly something producing those results is neither simple, nor would it be cheap.
Probably it would not be simple, cheap, or easy to duplicate, either.
That’s the conclusion I’m approaching.

#### LowQCab

Joined Nov 6, 2012
2,342
"" You are missing the point that these are not acoustic speakers. ""

Yes, in fact, they are "acoustic-speakers",
and it's spelled-out in black and white, proper English words on their website,
complete with some rather "hokey" pictures of how the "Ultra-Sound" converts into "Acoustic-Sound",
no special "interpretation", or special knowledge is required to understand what is being said.
There is no mistake.

Their claim is that the "energy" produced is not plain-old Sound, but "Ultra-Sound" which manipulates
the Air "in front of the speaker" so that it appears to behave like a much larger speaker.
Have You never experienced a true BS-Artist ?, probably not, but now You have.
and zero measurable, repeatable, concrete claims.

"" The Holosonic® technique for sound generation in the Audio Spotlight is a fundamentally different way of creating sound, and is not limited by the barriers facing traditional acoustics illustrated above. ""

Then why does it still have limited Frequency-Response EXACTLY like any generic, open-back Speaker ?

I have heavily thrashed Speaker-Design, on and off, since around 1972.
And professionally for around 6-Years total.
I know how Sound works,
and I've seen literally hundreds of bogus claims made over the decades,
and this product is nothing but "Swamp-Root-Snake-Oil" at its finest.

Build the Speakers in the Video above, then simply add an additional Ceiling-Tile to
the back of it, spaced-out about ~3-inches,
then fill the gap between the 2 Tiles with generic Fiberglass-Building-Insulation,
you'll be way ahead of the game, and You can then sell them for ~\$800.oo a piece.
They might even work better than the commercial units !!!
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#### MrSalts

Joined Apr 2, 2020
2,097

#### k1ng 1337

Joined Sep 11, 2020
648
Maybe I missed it, what is the purpose of all this? Sounds very interesting.

#### MisterBill2

Joined Jan 23, 2018
12,704
As I read the attached links, I am reminded of the "Sweet Sixteen" speaker system, the design and construction printed in a 1962 issue of "Popular Electronics" magazine. The claims for that creation were that "it sounded really good", which were probably true.
Certainly there are effects caused by phased arrays of radiator devices that may not be quite intuitive. And the mixing of ultrasonic frequencies to produce audible frequencies has been demonstrated many times. So it is clear that mixing products exist and produce interesting results.
It is also obvious that none of this is simple, and while the math can prove that it happens, the mechanisms of control are not so very simple.

#### Ya’akov

Joined Jan 27, 2019
6,275
Hey, @djsfantasi—sorry I missed this message until now.

I haven’t built a parametric speaker myself but I saw a small array at a hardware hackathon and experienced the effect which is a little creepy, especially if you don’t know what is going on. The demo I saw was not high fidelity and was small scale.

I don’t know about how much the nearby objects, which do cause demodulation, will interfere with the stronger, direct perception. The numbeer of speakers you need might make DIY versions unattractive even if you could do it well enough for your application. It does require a lot of transducers and (apparently) a lot of tuning.

If the commercial product is good, I suppose it comes down to a cost-benefit analysis, with your time as a substantial part of the cost in the DIY case (assuming we operate under the assumption it is a matter of time ot make it work the way you want) and money being the substantial part of the commercial version with the additional benefit of a known outcome.

The technology works, and in principle you could build it, but in practice for your project the commercial seems best.