Important discussion about pitch frequency and sound with silent subliminals

[Tap]

01/19/2015 at 6:29 pm

I would like to start a discussion about sound because I think it is very important to understand it when dealing with the type of silent subliminals we use. I actually just researched this all over the past few days.

https://www.youtube.com/watch?v=VxcbppCX6Rk

I attached a youtube video above to start with. I myself only can hear sound at 15,000 hz. Above that, I just hear clicking which means I can’t hear sound above that.

I start with that because when we encode our silent subliminals, we do two things to it. We change the sound intensity, or the amp which is measured in dbs. We also change the frequency using the nyquist prompt. Frequency is measured in hz.

(highpass8
(lowpass8
(mult
(lowpass8 (highpass8 s 300) 7000)
(hzosc 45000)
(hzosc 59500))
24000)
15000)

In seeing an audacity forum, what the above does is change the frequency to 14,500 hz from the 59,500-45,000. I am not sure if that is entirely accurate but from what I read, that’s what it does. From the youtube video above, that is bordering on barely hearing the sound. This is why I believe chirping is heard at higher (less negative dbs). If that was increased to 16000hz or higher, than no chirping would be heard by adults and only possibly by children.

Anything higher than 20,000hz is considered ultrasonic. You may have seen subliminals advertized on that. We ourselves could make it that high, but we definitely would hear nothing.

One important thing to note, and it’s something that I give credit to Fizbin for identifying. I was wrong when it comes to volume. You SHOULD NOT put it on high volume. Putting it on high volume will cause irritation, headaches, and possibly ringing of the ears. The reason for this is because it’s like you’re in a concert with high volume speakers in your ear nonstop. Even though you can’t hear the sound, because the frequency is so high, your ear hairs will still hear it and as the video above states, you will have hearing loss if done consistently because these ear hairs will be damaged.

The correct volume to play it would be at the same level as a typical song that you can hear. This is especially important if you are using headphones.

The question then becomes the amps. If you use -17 amp vs -40, at a lower volume, the -17 amp will have more chirping. Theoretically, the subject would hear that better than the -40 amp. It makes sense then to boost the amp, but put a lower volume, making sure you won’t lose your hearing. I’m curious what everyone’s opinion on that is?

[Tap]

01/19/2015 at 6:46 pm

I bring this up because I routinely use headphones with my own subliminals. Sometimes I would put the volume high so I could hear the squeaking well. However, I only recently started noticing a bit of ringing in my ears after listening for awhile. Since I can hear the 15,000hz my ears are about normal because I am under 40. I’m not worried about my hearing because I can still hear well.

Obviously, I know now not to put it that high. In fact, I’m kind of paranoid to use headphones now after my research. Putting it on high volume with just the sound device and no headphones is probably not that bad, if any of you have been doing that. I’ve been doing it for about a year now. It’s like if the subject is far away, it probably wouldn’t cause hearing loss. But if the speakers were near the subject, then it might be a problem.

It’s safer to place it at a volume that is at a comfortable level. What I do not is play a loud rock song and put it at a comfortable volume. Then I switch it to my silent subliminal. From what I read, you shouldn’t have any issues.

[Alen]

01/20/2015 at 9:37 am

Thanks Tap. I have been following your posts about this and I agree with what you’re saying. This is very helpful information.:D

[Tap]

01/21/2015 at 8:26 pm

Alen, I am glad this was helpful.

All,

I actually did more experiments to test all this. It’s one thing to read it and it’s another to hear it for yourself. I made the following short subliminals based off of a typical TextAloud .wav file that we all use to edit in Audacity, to test my hearing on it:

Subliminal #1. Amp = -17, Resampled Tracks to 192000. Used same Nyquist Prompt recommended by Trainer.
* Typical subliminal that I usually make with a higher amp than Trainer’s. Squeaking is loud. This is at 14,500 hz.

Subliminal #2. Amp = -17, Resampled Tracks to 192000. No Nyquist Prompt used.
* The result was a file that sounded much like the original .wav file after Text Aloud with the voice clearly heard, but at a lower volume. Lower by -17db to be exact. Interestingly, when I compared the sound of this subliminal with subliminal #1 at the same speaker volume level on my computer, this custom was louder by a good margin than the one above with squeaking. This subliminal did not have a change in frequency from normal sounds so presumably it’s at normal speech which is around 4,000hz.

Subliminal #3. Amp = -17, Resampled Tracks to 192000, but modified Nyquist Prompt to:
(highpass8
(lowpass8
(mult
(lowpass8 (highpass8 s 300) 7000)
(hzosc 45000)
(hzosc 62500))
24000)
15000)
*The frequency of this subliminal was changed to 17,500hz, although I am not sure what the lowest numbers mean exactly. At the same volume speaker level as #1 and #2, this one was considerably harder to hear but squeaking was still heard. This is because my hearing level is only really good up to 15,000 hz but the db must have been loud enough to still be heard.

Subliminal #4. Amp = -17, Resample Tracks to 192000, but modified Nyquist Prompt to:
(highpass8
(lowpass8
(mult
(lowpass8 (highpass8 s 300) 7000)
(hzosc 45000)
(hzosc 66500))
24000)
15000)
*The frequency of this subliminal was changed to 21,500hz. This would be considered ultrasonic range. At the same volume speaker level as #1, #2 and #3, this one basically could not be heard with barely a squeak.

My conclusion is as follows. With a constant db, at the same volume speaker level, the higher frequencies (15,000hz and up) proved to be softer and softer in sound as the frequency increased. Db does not change due to frequency, so this is why even if something has a very high frequency at 20,000hz but the db is really high, even though you can’t hear it well, your ear hairs will feel it and this can cause hearing loss.

Keep in mind however, even at the highest volume of my unedited -17 amp version, the voice talking was loud but not at shouting level really. However, if this is played constantly at the highest volume, I can see how it can be annoying or numbing to your ears.

The best thing I recommend from this little experiment is what I suggested early. Play a normal song at a comfortable level and switch to your silent subliminal at that volume level. That should be just about the right volume.

However, consideration must be given to your amp level. If you use a really low amp like -40, the voice unaltered similar to my subliminal #2 sounds lower at the same volume level compared to the -17 version. In that case, it’s up to you whether you want to increase your volume on your silent or not.

[Fizbin]

01/22/2015 at 2:31 am

Now for a little of the mathematical acoustics behind all of this …

The Nyquist formula being used is doing basically the same thing as an old AM radio transmitter – overlaying an audio signal onto a carrier wave. In this case, however, the carrier is not in the RF spectrum, but in the high audible/low ultrasonic band. To understand this, you need a bit of background information:

Normal audio is considered 20 through 20,000 hertz. Anything below 20 is considered subsonic, and from 20Khz up is considered ultrasonic.

The sampling rate is how many times per second the digital system measures (or “samples”) the signal being processed. A long time ago, some digital processing engineer named Nyquist (yeah, that’s where the function name comes from) figured out that to effectively retain information coming at a given frequency, you need to sample it at a rate least 2x higher than the top frequency you intend to process.

Most of the “information” in the human voice is in the frequency range between 400 and 4500 Hz (some lower and higher frequencies make it pretty, but you need those frequencies to make it intelligible). The phone company has made use of this for a long time by filtering the signals down to around 5000 Hz. (now you know why even the best phones sound horrible).

When you overlay one variable signal over a higher frequency sine wave, the variable signal “modulates” the other wave. This produces a very messy signal with a frequency band centered on the high frequency “carrier”, and extending both above and below it by the frequency range of the modulating signal. The frequencies above and below are called the upper and lower sidebands respectively. (Those of you who remember CB radio might start getting interested here…). The entire information content can be represented by a Single Side Band, so if you filter out the carrier and the other side band, you can pump all of your power into that one side band and still have a decodable signal at the other end.

The last bit of background is, when you overlay two “perfect” sine waves, the result is new site wave at a “beat” frequency of the difference between the two inputs. In other words, if you overlay a 45,000 Hz and a 60,000 Hz sine wave, you get a beat wave of 15,000 Hz.

Now, we will look at the formula.

(highpass8
(lowpass8
(mult
(lowpass8 (highpass8 s 300) 7000)
(hzosc 45000)
(hzosc 59500))
24000)
15000)

The underlined section takes your input (s), and filters out information below 300hz using the highpass function, and above 7000hz using the lowpass function.
The bold area takes the results of that function, and overlays it on perfect sine waves at 45000 and 62500 hz. Those two perfect sine waves beat together to get a 14,500hz carrier wave for the 7khz bandwidth modulating signal.
The final filter basically removes the carrier and lower sideband by filtering out sounds below 15,000 hz, and above 24,000 hz.

There you have it. An “ultrasonic” subliminal.

[trainer81]

01/22/2015 at 9:14 am

Hmm, maybe I should change the name from “silents” to “ultrasonic” that’s kind of catchy.

Thanks for sharing

[Tap]

01/22/2015 at 6:24 pm

Thanks for the explanation Fiz. I know you are very knowledgeable about topics of sound. So the frequency of the nyquist we use is 14,500hz. Ultrasonic would be in the range of above 20,000hz.

To Trainer’s idea, I am not sure if it would truly be ultrasonic, unless the nyquist prompt is something like:

(highpass8
(lowpass8
(mult
(lowpass8 (highpass8 s 300) 7000)
(hzosc 45000)
(hzosc 65500))
30000)
15000)

That would be a frequency of 20,500hz, in the ultrasonic range. I increased the filtering out of the high range at 30,000 but I am not sure if that would have any effect.

I do know that would make the subliminal truly silent from my experiment. I just don’t know if it would be as effective as the normal Nyquist prompt we use.

I found the following post interesting from the audacity forum. It looks like this person doesn’t reduce the amps or db. Also the nyquist prompt used is slightly different.:

http://forum.audacityteam.org/viewtopic.php?f=13&t=53615

To create “silent subliminal” speech that is above the frequency threshold of hearing, follow the following steps (this may not work in Audacity 1.2., so ensure that you are using 1.3.13, which you can get from here: http://audacity.sourceforge.net/download/)

First you need a good quality (low background noise) voice recording that is to be “encoded”.
Set the Project Sample Rate (lower left corner of the main Audacity window to 192000 (type the number into the box).
“Tracks menu > Resample” to up-sample the track to 192000 Hz.
“Effect menu > Nyquist Prompt” and copy the following code into the Nyquist Prompt box:

Code: Select all
(highpass8
(lowpass8
(mult
(lowpass8 (highpass8 s 300) 7000)
(hzosc 45000)
(hzosc 59500))
20000)
14000)

Set the Project Rate to 44100
“File menu > Export” to export the finished track as a WAV file.

Notes:

You will need either high quality speakers, or ultrasonic transducers to be able to play the resulting sound.
If you play back this recording over normal speakers, there is a risk that it could burn out the tweeters. It is essential that you do not turn the volume up beyond normal listening levels. Even at normal listening levels there is a risk that it could destroy the tweeters in the speakers as the high frequency content is far higher than in standard audio recordings.
Many experts in the field of subliminal messaging claim that if your ears cannot hear it, then it will have no subliminal effect, but that if your ears can hear it, then it will be extremely irritating to listen to.
It is essential that you do not listen to this recording at high volume level as it could cause permanent damage to your hearing. This is especially important if you listen through headphones. KEEP THE PLAYBACK VOLUME LOW.
Many commercially available “silent subliminal” are totally safe to use because they really are silent (no sound at all). The technique described here is not “silent” – there will be high frequency sound that may be above or close to the limit of your hearing threshold, but it is not silent – hence the important warnings. Use at your own risk, but please heed the warnings.
I make no claims regarding the safety or effectiveness of this technique. It is only intended as a demonstration of a simple implementation of Lowry’s silent subliminal presentation system (US Patent 5,159,703 October 27, 1992).

[Fizbin]

01/22/2015 at 7:12 pm

Yeah, I read that article a while ago. There is also an Audacity subliminal plugin that has the Nyquist formula built in, and lets you simply set the carrier frequency.

They all do about the same thing. It isn’t exactly high precision, and the differences are probably less than the differences between individual listeners.

[Tap]

01/23/2015 at 6:13 pm

Fiz,

Let me ask you then. Ever since all this research, I’m paranoid to listen to my own subliminals with headphones because my hearing may be affected even if I put the volume lower. I read something that higher frequency sounds in general are not good to be exposed to. However, I’ve also read articles that higher frequency sounds are just fine to listen to and it depends really on the db of the sound.

I am not worried about playing the subliminals without a headphone. At an appropriate level, I am pretty sure that has no affect on hearing. However, the issue is with headphones and being right in the ear. What is your opinion?

Also, I was thinking of experimenting with making the subliminals in the 20Khz range, really ultrasonic. Those would be really silent, but not sure if they would be effective as the 14.5 Khz we make now. What is your opinion on that?

[trainer81]

01/23/2015 at 6:39 pm

Ah, if you listen with or without headphones it will be fine if it concerns a higher or lower frequency. Make sure the volume is at a level your use to.

20Khz range that would be an interesting test.

[Alen]

01/23/2015 at 7:52 pm

I have been listening to my own self improvement subliminals with headphones for myself and I just test the volume with a song. Also I have used headphones since I was very young because I play guitar and have an excellent sense of sounds around me, my ears even move slightly like a rabbit when I hear something from behind me. haha When I have used headphones if the volume is up too high it hurts my ears after a while same with listening to the subliminals. So I keep them down and also turn them down if my ears hurt. I think your ears would hurt after a while if they were too loud. But I haven’t read any research on this I just think it makes sense that they probably wouldn’t hurt your ears if the volume is low. Just my 2 cents, thanks again for the info.

[hotaceazn]

01/23/2015 at 10:07 pm

To make sure the volume is ok, since I make my own customs, I create a test which is basically the sound file before the changes are made to it. I use that to gauge the volume since basically all i am doing is changing the frequency. There have been times I found it was to loud and I would lower the volume.

[Tap]

01/23/2015 at 11:25 pm

Right that makes sense, especially from my experiment. You figure it’s just the voice talking anyway. I suppose the higher frequency shouldn’t matter as much as the loudness of the voice talking. Either way my plan is to make subliminals using the -44 for that Trainer recommends, specifically to be used for headphones, and then put the volume lower. I think I’ll be extra safe like that.

Trainer,
Thinking about it, the only reason a 20khz subliminal would be good is that it’s extra silent, but you can put it on full blast and really no one would hear it. Even maybe not even decreasing the amp and keeping it the same. The result would be a loud subliminal to the ear but silent in reality because it’s way above human hearing range. Of course the full blast volume would be so loud it fills the room more. However, with this discussion, hearing may be affected.

When I put my subliminals with the -17amp full blast, clear squeaking is heard. If that was in the 20khz no squeaking would be heard at the same volume. It’s like a dog whistle. Dog whistles are around 25Khz frequency, but the dbs are loud like around 90dbs. Our subliminals are a lot lower than that. We can’t hear dog whistles. Imagine someone blowing a dog whistle constantly. Now that would affect your ears.

[Fizbin]

01/24/2015 at 4:26 am

Exactly!
Safety is all about the playback levels, while silence is about the frequency range compared to the listener’s hearing.

[Tap]

01/25/2015 at 9:52 pm

https://dreamgirlsgt.com/forum/prime-general-discussions/important-way-to-know-what-volume-to-play-your-subliminals-at/

See the thread above for the best way to determine the correct playback volume level.