045Be and ~50kHz ultrasonic hearing

[hapy._.face]

When I discovered JBL had made a tweeter that was capable of reproducing frequencies in the 48kHz neighborhood, my immediate question was- why?

I know- to slay bats and train dolphins, right?

...but seriously:


http://www.audioheritage.org/html/pr...logy/045be.htm

'The new DVD formats can record information to 50khz and beyond'

Frequencies above the 20kHz are considered ultrasonic. So what human can even hear anything at 48kHz? I discovered that children can hear higher frequencies adults cannot. I also learned that if ultrasound is coupled directly into the skull bone and reaches the cochlea without passing through the middle-ear, much higher frequencies (up to about 200 kHz) will be audible. This effect (sometimes called ultrasonic hearing) was first discovered by divers exposed to a high-frequency (50 kHz) sonar signal.

Still my question remains- 'why'? Assuming that the ultrasound can couple with our skulls and an audible sound is generated- what would it sound like? Is it musical? Is it a marketing gimmick?

[Zilch]

035TiA plays to 27 kHz, and 2407H (and similar), presumably, to 30 kHz.

Does anyone perceive these to be of any consequence other than specsmanship?

The TV still whistles, no doubt. Does it have subliminal sub- (or supra-) auditory effect when on, now that I (gratefully) can no longer hear it?

[Mr. Widget]

Does anyone with a normal sized room average sensitivity speakers need a kilowatt amp? I really don't know the answer to that question... but I will tell you the the part of the spectrum that I can hear sounded significantly better through the 045Be than it does through a 077/2405 or even most dome tweeters.


Widget

[Titanium Dome]

There's a phenomenon by which frequencies generated above human hearing can interact to create audible tones due to the intermodulation of the unhearable frequencies. I believe this occurs naturally in "live" sound, and can be imitated in generated sound. This interaction assists in directionality if I remember correctly.

Of course, I have no source for the moment, but you can rest assured I'll get one for you.

Where's that darn book?

[Ian Mackenzie]

They cost enough..one would hope so.

I think the 48 khz is the marketing grab taken from ADAT. The reality is that the new transducers have incredibly low moving mass and alot of other clever wiz bang technology that makes them more accurate at the lower end of their working spectrum. The drivers that traditionally run from 1 khertz up to 20khertz on paper as a rule run out of puff (transient speed) due to the greater moving mass and other stuff.

However this is only true of current art, future Art may tell a different tale. We will have to wait and see.

[Titanium Dome]

From http://www.nae.edu/NAE/bridgecom.nsf...R?OpenDocument

Ultrasonic Audio
Ultrasonics can be used to produce highly directional audible sound beams. This technology is based on physical properties of air, particularly that air becomes a nonlinear medium at high sound pressures. Hence, it is possible to transmit two high-intensity ultrasonic tones, say at 100 kHz and 101 kHz, and produce an audible 1 kHz tone as a result of the intermodulation between the two ultrasonic tones. However, the demodulated signal will be significantly distorted, so the audio must be preprocessed to reduce the distortion after demodulation (Pompei, 1999). Although this technology is impressive, it cannot reproduce low-frequency sounds effectively, and it has lower fidelity than standard loudspeakers.

Check out some of the relevant references at the bottom of the Web page. This information is four or more years old, BTW, and a lot has developed in the years between 2002 and 2006.

[Titanium Dome]

Lord, I love eggheads. They do so much good work and share it freely with their peers and with us.

Here's an ASA presentation from NOISE-CON 2005. I'll bet they partied that night!

http://www.acoustics.org/press/150th/Lenhardt.html

[Titanium Dome]

At least one company is developing a market already.

http://www.atcsd.com/pdf/HSS%20Product%20Sheet.pdf

[hapy._.face]

Hi(gh) Ti(de),

Thanks for the info! That's interesting stuff, indeed.

At least one company is developing a market already.

http://www.atcsd.com/pdf/HSS%20Product%20Sheet.pdf

Now that is interesting- a column of ultrasonic signals that isolates the audible portion of the program material so that the material itself can be focused into a given target. Shopping will never be the same- Gee, I can't wait to get beamed advertising jingles as the ultrasonic frequencies are coupled into my freakin skull. Does this mean the audible jingle will play in my head for several seconds after leaving the audible target/store?

Hence, it is possible to transmit two high-intensity ultrasonic tones, say at 100 kHz and 101 kHz, and produce an audible 1 kHz tone as a result of the intermodulation between the two ultrasonic tones

Like an out-of-tune guitar, eh?


I think it's cool to see all of this technology and sound experimantation, but my question stems from a high fidelity sound reproduction perspective. I gather the 045Be it is not an intermodulated tone generator (on purpose). Nor do I think it will be beaming columns of USF so that I will have a greatly diminished sweet spot.

I guess (as Widget indicates) it's not what it can do at 48kHz that makes it what it is- it's what it does as a (listenable) UHF device that makes it special. Hey Widget- do you really think it can ground a bat!?

[moldyoldy]

Hi, H. .F,

Here's what I thought to be a very interesting read on the topic, in particular, how it relates to music;

http://www.cco.caltech.edu/~boyk/spectra/spectra.htm

As pointed out already, even though we may deny perceiving UHF, some of it can even penetrate half-deaf, thick skulls like mine. What surprised me were the effects as they relate to music, and our perception of it. My impression, after reading the linked article completely, was that it might be wise to filter out everthing over 20kHz for the best enjoyment of music playback in systems that can go beyond it. Your analogy to the warble or "beat" frequencies made by an out-of-tune guitar is appropriate. I was also surprised to learn that 40% of the energy of a cymbal crash is over 20kHz.

Also, Roger Russell noted that subharmonics of UHF resonances can be audible, in a musically-negative way, at least with aluminum diaphragms, which may be a little OT, as I'm not familiar with the driver you mentioned.

[hapy._.face]

snip....'Roger Russell noted that subharmonics of UHF resonances can be audible, in a musically-negative way...

More interesting stuff!

Regarding the quote above- do you interpret this as meaning the subharmonics of UHF "cut" into other frequencies to compete for SPL's? ...as in the concept behind using bass traps- but on the other end of the spectrum?

[moldyoldy]

More interesting stuff!

Regarding the quote above- do you interpret this as meaning the subharmonics of UHF "cut" into other frequencies to compete for SPL's? ...as in the concept behind using bass traps- but on the other end of the spectrum?

I interpret it as 'in addition to' the recorded material, in an IM distotion kind of way.

[hapy._.face]

I interpret it as 'in addition to' the recorded material, in an IM distotion kind of way.

OK.

I read the article, and it made me wonder if some of the "X" factor that live music has could be attributed to the stuff we can't hear but rather feel. If that is the case- there could be a genuine, phsychological affect ultrasonic frequencies have on us. Imagine if that were found to be true. Imagine if it were perfected. Imagine if movie makers could force audiences to cry!! Oh the horror!!

[moldyoldy]

Perhaps with a live orchestra, or other acoustic performances, but at a rock concert, it's just the stuff the guys in front of you are smokin'....

(edit)Most of the movies I've seen lately make me wanna cry anyway...

(re-edit) It may all be a rather moot issue anyway, as any UHF from a recorded performance would have to pass every link in the audio chain, starting at the mic or pickup, to ever make it to a UHF-capable transducer. The distortion effects however, bear further investigation.

[speakerdave]

I'm with Ian. I think uber frequency response translates by implication to transient response and clean waveform (no ringing) in the audible range.

David