Subliminal messages real or not? (OT)

Hi there. The other day we were talking about if subliminal messages in
music were real or not, and it ocurred to me what better people to ask
than people who make a living procesing music(some of you anyway). Im just
getting into the field of DSP, so havent got much experience, but I dont
see how could a person hide a subliminal message in the music, and make it
very hard to find via DSP means, but still make it audible. What are your
thougts on this?

		
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NightHawk skrev:
> Hi there. The other day we were talking about if subliminal messages in
> music were real or not, and it ocurred to me what better people to ask
> than people who make a living procesing music(some of you anyway). Im just
> getting into the field of DSP, so havent got much experience, but I dont
> see how could a person hide a subliminal message in the music, and make it
> very hard to find via DSP means, but still make it audible. What are your
> thougts on this?

First of all - Are subliminal messages for real at all? I don't know.

I've heard the story about subliminal messages in film, where some
single pictures containing ads for a certain beverage was inserted
in a movie. According to the story, none of the audience had noticed
the ads (at least consciously), but a large fraction of the audience
did feel an urge to have this particular beverage when they left the
theatre. Apparently, this experiment did result in some laws against
subliminal ads.

Some say the story can not be confirmed, though. The experiment, not
the laws which I believe are still in place. So I don't know what
to believe.

Now, *assuming* audio subliminal messages do exist, and *assuming*
they can be constructed and hidden in a music audio signal, it would
not be surpising if they can not be detected by means of DSP. It is
hard enough to extract intelligable speech signals known to be present,

from uncorrelated background noise (e.g. "black box" recordings from
aircraft accidents).

Extracting messages that may or may not be present in a signal that
at the outset is very similar to what you are looking for, would be
at least as hard.

Rune

NightHawk wrote:
> Hi there. The other day we were talking about if subliminal messages in
> music were real or not, and it ocurred to me what better people to ask
> than people who make a living procesing music(some of you anyway). Im just
> getting into the field of DSP, so havent got much experience, but I dont
> see how could a person hide a subliminal message in the music, and make it
> very hard to find via DSP means, but still make it audible. What are your
> thougts on this?

What sort of subliminal message? Something simple like "Buy Barfo beer"? 
I doubt it can be successfully done, so I doubt that it is done. You 
might me able to encourage popcorn sales by ensuring that the odor 
enters a theater's ventilation system, and you might sell drinks or 
encourage condom use with a single frame (1/24th second) flash on a 
screen, but images are seen all at once, while sound is perceived 
sequentially. The sound being too soft to be heard is like a flashed 
image having too little contrast to be seen, ineffective.

Many sound files have digital watermarks which go unnoticed by listeners 
but can be recovered by a computer. If a watermark or subliminal message 
were embedded in an MP3 file with enough clarity to be noticed, I guess 
it would be discoverable. But then it wouldn't be subliminal.

Jerry
-- 
Engineering is the art of making what you want from things you can get.
�����������������������������������������������������������������������

As always happens in this kinds of threads, lets narrow the definition of
"subliminal mesage" to only AUDIO. 

By subliminal message I mean a oral message encoded into the song/music
that is not related to the main theme of the song/music, and could cause
problems for the record company if discovered.
I dont necesarily messages that advertise satanist cults, suggest purchase
of a certain product, make you dance as a chicken or promote other mental
instability ascts, it just could be a hidden bonus or something...

Is it posible that such a message could be encoded (think mp3 watermark)
into the audio so that is not READLY audible, can not be detected by
simple tests like lisening carfully and playing at full volume...?

Just want to know if all that stuff about "subliminal messages" in music
is posible at engineering level.


		
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On Sun, 24 Jul 2005 17:31:50 -0500, "NightHawk"
<nightstalker_099@yahoo.com> wrote:

>As always happens in this kinds of threads, lets narrow the definition of
>"subliminal mesage" to only AUDIO. 
>
>By subliminal message I mean a oral message encoded into the song/music
>that is not related to the main theme of the song/music, and could cause
>problems for the record company if discovered.
>I dont necesarily messages that advertise satanist cults, suggest purchase
>of a certain product, make you dance as a chicken or promote other mental
>instability ascts, it just could be a hidden bonus or something...

   There are supposed subliminal 'meditation' tapes, new-age
recordings that supposedly give your subconscience positive,
life-affirming messages. I recall someone asking about this on
rec.audio.pro, and perhaps there being one or more other discussions
there on subliminal recordings.
   There were lots of popular recordings with backwards voices, I
recall an ELO LP said 'turn back' or something, but most amusing was
the first Bloodrock album (it was their second album that had
very-popular-but-never-heard 'D.O.A.') in the song "Gotta Find A New
Way" which has a backwards-recorded commentary on backwards recordings
in pop music.
   These recordings are not submiminal unless you believe people who I
consider in the tin-hat category. Here's one guy I recall hearing on
the Art Bell radio show in the late '90's:
http://www.reversespeech.com

>Is it posible that such a message could be encoded (think mp3 watermark)
>into the audio so that is not READLY audible, can not be detected by
>simple tests like lisening carfully and playing at full volume...?

   You can put such a message in a recording, but there's no known
mechanism for it to affect a person if they can't hear it. In other
words, this stuff appears to be bogus.
   Of course, audio watermarking is a different thing, intended to be
detectable by equipment but totally inaudible to listeners and not
affecting them in any way. A voice put in below audibility in a music
recording will be very diffucult to detect by equipment. I think an
audio watermark can only be detected because the equipment knows
exactly where (what frequencies) to look and what (what modulation) to
look for.

>Just want to know if all that stuff about "subliminal messages" in music
>is posible at engineering level.

   It's certainly possible to insert sounds that are just barely
audible, or just below audibility. Whether such sounds can have a
'subliminal' effect seems to be an open question, but there doesn't
seem to be hard evidence for it. Here's a webpage on the original
ideal of subliminal advertising in movies as well as in general
(sorry, this webpage isn't exclusively about audio):

http://www.snopes.com/business/hidden/popcorn.asp


>
>
>		
>This message was sent using the Comp.DSP web interface on
>www.DSPRelated.com

-----
http://www.mindspring.com/~benbradley

NightHawk wrote:
> As always happens in this kinds of threads, lets narrow the definition of
> "subliminal mesage" to only AUDIO. 
> 
> By subliminal message I mean a oral message encoded into the song/music
> that is not related to the main theme of the song/music, and could cause
> problems for the record company if discovered.
> I dont necesarily messages that advertise satanist cults, suggest purchase
> of a certain product, make you dance as a chicken or promote other mental
> instability ascts, it just could be a hidden bonus or something...
> 
> Is it posible that such a message could be encoded (think mp3 watermark)
> into the audio so that is not READLY audible, can not be detected by
> simple tests like lisening carfully and playing at full volume...?
> 
> Just want to know if all that stuff about "subliminal messages" in music
> is posible at engineering level.

I thought I answered that. Masking will make that unfearable, IMHO.

Jerry
-- 
Engineering is the art of making what you want from things you can get.
�����������������������������������������������������������������������

>NightHawk wrote:
>> As always happens in this kinds of threads, lets narrow the definition
of
>> "subliminal mesage" to only AUDIO. 
>> 
>> By subliminal message I mean a oral message encoded into the
song/music
>> that is not related to the main theme of the song/music, and could
cause
>> problems for the record company if discovered.
>> I dont necesarily messages that advertise satanist cults, suggest
purchase
>> of a certain product, make you dance as a chicken or promote other
mental
>> instability ascts, it just could be a hidden bonus or something...
>> 
>> Is it posible that such a message could be encoded (think mp3
watermark)
>> into the audio so that is not READLY audible, can not be detected by
>> simple tests like lisening carfully and playing at full volume...?
>> 
>> Just want to know if all that stuff about "subliminal messages" in
music
>> is posible at engineering level.
>

yeah you did. just wanted to narrow the discusion so it wouldnt include
more static images and the like, since its not really realted to DSP.
>I thought I answered that. Masking will make that unfearable, IMHO.
>
>Jerry
>-- 
>Engineering is the art of making what you want from things you can get.
>�����������������������������������������������������������������������
>


		
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Jerry Avins wrote:
> NightHawk wrote:
> 
>> As always happens in this kinds of threads, lets narrow the definition of
>> "subliminal mesage" to only AUDIO.
>> By subliminal message I mean a oral message encoded into the song/music
>> that is not related to the main theme of the song/music, and could cause
>> problems for the record company if discovered.
>> I dont necesarily messages that advertise satanist cults, suggest 
>> purchase
>> of a certain product, make you dance as a chicken or promote other mental
>> instability ascts, it just could be a hidden bonus or something...
>>
>> Is it posible that such a message could be encoded (think mp3 watermark)
>> into the audio so that is not READLY audible, can not be detected by
>> simple tests like lisening carfully and playing at full volume...?
>>
>> Just want to know if all that stuff about "subliminal messages" in music
>> is posible at engineering level.
> 
> 
> I thought I answered that. Masking will make that unfearable, IMHO.

Bah! "make that unfeasible".

Jerry
-- 
Engineering is the art of making what you want from things you can get.
�����������������������������������������������������������������������

My degree is in experimental psychology (and maths). One of our
lecturers did a lot of research into "subliminal perception",
attempting to replicate many of the published experiments, and was
unable to obtain any statistically significant results. He had a lot of
problems getting his papers published.

Leon

I agree with Rune that it may be nigh on impossible to
detect by strict DSP means (assuming of course that such a
phenomenon exists).

The human auditory system is however, a different kettle
of fish. A number of years ago, I listened to a very
interesting interview on radio, where the interviewee
was involved in researching intelligibility limits in
human hearing. Anyway, the crux of the interview was
a demonstration, where a short passage (1-2 secs) of
noise was played back. The interviewee then uterred a
sentence and played the noise passage again. On the second
pass, I could clearly hear the word 'Apple' in the noise.
He had in some context used the word apple in the sentence
he spoke in between the two passages.

No specific details of the research or the suspected mechanisms
were given in the interview (and I'd had x+1 Barfo's that evening,
- it was Summer :-) ). My own (humble) take on what was going on,
was that the neural pathway involved in processing the spoken
word 'Apple' had remained sensitised for a while and subsequently
acted like a matched filter on the second noise passage so as to
significantly increase the (perceived) SNR of the passage.

I'm no perceptual/psychoacoustic modelling expert, some people here
on this forum are much smarter than me in this fascinating area.
However, to me, this sounds more like a job for Neural Networks
with extremely fast pattern matching capabilities.

Dave.