Silent subliminal function

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Re: Silent subliminal function

Permanent link to this post Posted by steve » Sat Jun 11, 2011 12:58 pm

cubboy wrote: Is there any way to tighten the bands a bit further,

Yes, you can reduce the bandwidth of the audio signal, for example:

Code: Select all
(setq CarrierFreq 17500)
 
(highpass8
(lowpass8
(mult 2
(lowpass8 (highpass8 s 300) 3000)
(hzosc CarrierFreq))
CarrierFreq)
CarrierFreq)

but the trade-off is that the sound quality is reduced.

If you mix the "silent subliminal" with some music (as in my example), the chirping will be largely masked by the music, even if the carrier frequency is clearly audible on its own. (It would be pretty boring to listen to "silent subliminals" without "background" music with it ;) )
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Re: Silent subliminal function

Permanent link to this post Posted by cubboy » Thu Jun 16, 2011 9:34 pm

Steve, do you think sound quality will be reduced detrimentally, or just cosmetically? I'm having success (a placebo test on my brother) with the the latest code you posted
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Re: Silent subliminal function

Permanent link to this post Posted by steve » Fri Jun 17, 2011 10:13 am

If you encode and then decode some audio you can hear for yourself that reducing the bandwidth of the audio signal reduces the sound quality.
If you mean, "will the subliminal suggestions still work?", I've no idea. Scientific opinion on the subject mostly suggests that there is little if any real effect, but science doesn't have all of the right answers.
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Re: Silent subliminal function

Permanent link to this post Posted by Big Dawg » Wed Jul 06, 2011 5:44 pm

Durig my research for making my own silent sublimianals with Audacity, I came across the remark that you dn't want to play these subliminals at the hight volume leves, as it would cause Inner Ear Damage. Been thinking about it for some time now, and got to wondering, would this Inner Ear Damge be caused because the embedded Silent Subliminal was recorded at a high volume level as well? And thus, the volume, the amplitude if you will, would over drive the inner ear at these higher volume levels?
I'm thinking that if this actually is the case, then perhaps using the Amplification Effect, and limit the signal peaks to somewhere in the -25 - 35 db lever just might resolve this issue. But then, I am only guess at this, and am looking for some authoritive input here. Any assistance is greatly appreciated.

Thanks
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Re: Silent subliminal function

Permanent link to this post Posted by steve » Wed Jul 06, 2011 6:53 pm

Big Dawg wrote:I came across the remark that you dn't want to play these subliminals at the hight volume leves, as it would cause Inner Ear Damage.

I think that was a remark that I made.
"Normal" audio contains only a small amount of very high frequencies relative to other frequencies. A "silent subliminal" audio recording, if not mixed with other audio, contains 100% very high frequencies at high amplitude. The risk of hearing damage will depend on the volume level that you are listening at, but as this is dealing with frequencies in the upper ranges of perception it is difficult to judge just how high the playback level actually is. I depend on my hearing for my work as well as everyday life and pleasure and I'd personally prefer to avoid unnecessary risks to my hearing.

Did I also mention damage to speakers? In a multi-driver speaker system, the tweeters (high frequency drivers) are designed with much lower power handling capability than the bass/mid-range speakers. Sending high levels of very high frequencies to a multi-way speaker can burn out the tweeters. This is possibly another indication that it may not do ones hearing much good.

Mixing the silent subliminal with other sounds, and keeping the silent subliminal say 20 dB lower than the other sounds is probably safer as you can then get some idea of how loud the sound is.
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Re: Silent subliminal function

Permanent link to this post Posted by Big Dawg » Thu Jul 07, 2011 2:25 am

Thank You Steve:

I appreciate the reply. Yes, after looking over the other posts, you did indeed mention damage to the tweeters. And one last thought. You had mentioned in your reply, that perhaps 20db below the masking audio would be better. Like You, I too depend a great deal on my hearing, and was guessing that the 25 - 30 db below range might be a bit safe for one's hearing.... and tweeters. I've been thinking that it is the "Amplitude" of the Silent Subliminals rather than the frequencies that would do the damage. The frequencies would just put it in the range to where dogs and other animals would be able to hear it. The Amplitude, would be the force that would do the damage... like getting hit with a High Pressure Water hose.
Again, Thanks a lot Steve.
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Re: Silent subliminal function

Permanent link to this post Posted by steve » Sun Jul 10, 2011 10:38 pm

Update:
Edgar-rft has developed the code further and created a plug-in for making silent subliminals which he has posted here: viewtopic.php?f=39&t=58548

The code in Edgars plug-in is a little more complex than the examples in this thread, but has the added convenience of being installable as an Audacity effect. It also uses a highly effective "brick-wall" filter to limit the bandwidth of the audio before modulation, and to suppress the lower side-band. These technical improvements improve both the quality of the modulated signal by preventing aliasing, and make the result "more silent" as frequencies below the carrier frequency are almost completely removed.
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Re: Silent subliminal function

Permanent link to this post Posted by karanmouse » Fri Aug 05, 2011 5:52 pm

Well... It is mentioned in the subliminal recording software that the freq should be 16500hz for silent subliminal. Steve i dont know how to make changes in the nyquist code you gave.
(highpass8
(lowpass8
(mult
(lowpass8 (highpass8 s 300) 7000)
(hzosc 45000)
(hzosc 60500))
20000)
15000)
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Re: Silent subliminal function

Permanent link to this post Posted by steve » Fri Aug 05, 2011 8:02 pm

Scroll back a few posts before this one - the last code example I gave starts with "(setq CarrierFreq 17500)". To change the frequency to 16500 Hz, just change the "17500" to "16500". Alternatively, why not try Edgar's plug-in.
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Re: Silent subliminal function

Permanent link to this post Posted by karanmouse » Sat Aug 06, 2011 10:42 am

steve please provide step be step procedure to try Edgar's plug-in.
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