Silent Subliminal presentation system.

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relief
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Silent Subliminal presentation system.

Post by relief » Wed May 05, 2021 5:53 am

There is a thread here which posted a Nquist script to generate a silent subliminal based Lowery's patent: https://patents.google.com/patent/US5159703A/en

The thread containing the script: viewtopic.php?f=42&t=58548&hilit=subliminal&start=90

I think the script posted on that link generates a single sideband, suppressed carrier amplitude modulated signal. Lowery's patent also describes a frequency modulated signal, is it possible to make a script for this?

Instead of modulating the message, can we just upconvert the speech signal to an inaudible frequency like above 16KHz?

kozikowski
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Re: Silent Subliminal presentation system.

Post by kozikowski » Wed May 05, 2021 9:49 am

You can try.

Effect > Change Pitch is one of the effects that can cause sound damage if you push the conversion too far. NowAvailableAtYourLocalEmporium.VoidWhereProhibited.LicensedDriversOnly.

Change Speed, well, changes the speed of the speech.

Subliminals can run into a number of real-world problems.

You have to be able to put about 4KHz worth of sound somewhere. That's minimum needed for intelligible speech. 4KHz plus 16KHz is 20KHz where most if not all sound systems lose it.

It's a safe bet you can't use 44100 sampling frequency. Everybody says you can do sound up to 20,000Hz that way, but that's after playing digitizing tricks and games. Without the tricks, 44100 is only perfect and unambiguous out to about 17000Hz. That doesn't leave you a lot of room for another voice up there.

And that brings us to playback. Your speakers or headphones have to be good out to the highest pitch sound with modulation. That will usually peel off most speakers, so that leaves headphones.

You should sort where you're going to plug your wired headphones. Wireless has trouble with regular music much less ultra-sonic presentations, and most internal soundcards won't pass anything over 19,000Hz or so.

USB services can have tonal restrictions as well.

You can't use MP3. MP3 actively looks for inaudible sounds so it can ignore them. MP3's tiny, convenient files are not "free."

So past all that, you're good to go.

Koz

steve
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Re: Silent Subliminal presentation system.

Post by steve » Wed May 05, 2021 12:25 pm

relief wrote:
Wed May 05, 2021 5:53 am
Instead of modulating the message, can we just upconvert the speech signal to an inaudible frequency like above 16KHz?
You can use any method you like to make the audio inaudible and it won't make any difference. If you can't hear it, then you can't hear it.

There is some weak evidence that suggests that audio "messages" may have some subconscious effects if the audio is on the threshold of hearing (very much in the background so that you cannot easily make out the words). The scientific evidence in support of this is inconclusive, but there may be some effect.

On the other hand, if the audio is "silent", or "inaudible", or "encoded", then the scientific evidence shows no effect at all, though there are many charlatans that make claims to the contrary.
relief wrote:
Wed May 05, 2021 5:53 am
I think the script posted on that link generates a single sideband, suppressed carrier amplitude modulated signal.
Yes, it's "AM modulation".
relief wrote:
Wed May 05, 2021 5:53 am
can we just upconvert the speech signal to an inaudible frequency like above 16KHz?
If by "upconvert" you mean "pitch shift", then that's not possible.

The problem is that the frequency range of speech is around 150 Hz to 7000Hz, with the dominant intelligible centre frequency around 1000 Hz. Even if you limit that frequency range (by filtering) to a range of 300 to 3000 Hz (similar quality to "walkie talkies"), that's still over 3 octaves.

To be "inaudible", the lower end of the frequency range would need to be shifted from 300 Hz to 16,000 Hz, which is a huge shift. That same shift would push the upper end of the frequency range (3000 Hz) up to around 150,000 Hz. That would require a sample rate of at least 300 kHz. The frequency ranges involved are far too high for any normal audio equipment.
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kozikowski
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Re: Silent Subliminal presentation system.

Post by kozikowski » Wed May 05, 2021 6:02 pm

I did hear a multiple message presentation a while back. It was a "forward" voice and one or two lower volume background voices at the same time with different messages.

It was remarkable that my head could keep track of all that and make sense of the messages. It was also exhausting. It used up the ear's ability to derive meaning by running everything flat out. It also borrowed attention from other parts of the mind. That's when you drive off the road. So this isn't the sleep-learning or relaxation method people claim.

There is one engineering trick to keep in mind. Making the work and presenting it is only the first 2/3 of the exercise. Testing is a big deal. Broadcasters have a periodic "Proof Of Performance" where they test and certify that the antennas on the hill are working as they should. This is just the most fun for engineers because it usually happens between 1 am and 4 am.

We need the Subliminal Proof of Performance. I need to be able to accept a sound file from you and give you back the original, clear, unprocessed voice.

Koz

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