I was doing some digitizing of voice recordings when I found a
surprising effect. The first zip file linked below is of a voice
recording in MP3 format. The digital sampling rate was at the default
44khz. The second zipped file is the result when I applied the slower
sampling rate of 8khz to the first file.
I was surprised to note the effect of using the slower sampling rate
was to give the recording the sound of whale song or dolphin speech.
(Note: I copied below discussion of experimental evidence that dolphins
do use a form of "speech".)
This effect is more pronounced with longer recordings. I had to shorten
these to upload them to the forum. To observe this, use a program for
digitally recording audio, then sample a saved voice recording at a
slower rate than it was originally saved at. There are several free
programs available on the net that have this capability.
I thought then perhaps the difficulty in interpreting dolphin speech
was that we record them at a slower sampling rate than what they are
actually produced at. However, it is known that dolphin speech extends
into higher frequencies:
Oceanwide Science Institute's Research Page.
"One of the main problems is the high frequency content of dolphin
signals. Most dolphin species produce three types of signals:
echolocation clicks, the faster paced burst pulse clicks, and whistles.
Echolocation clicks are used by dolphins to detect and recognize
objects in the water from the returning echoes. Burst pulse clicks and
whistles on the other hand are thought to be used mainly for
communication. Click signals are extremely short (50 microseconds) and
broadband high frequency signals, ranging from 0 to over 200 kilohertz.
Whistles are generally within human hearing range, but also have
ultrasonic components called harmonics which can go up to over 100 kHz.
However, conventional audio recording systems only go up to about 20
kHz (also the upper limit of human hearing), and therefore miss the
major part of these signals."
http://oceanwidescience.org/docs/4ch-UDDAS.html
The higher frequencies necessitate higher sampling rates to accurately
record the analog signal. This is a result of the Nyquist theorem:
Nyquist's Sampling Theorem.
http://www.cs.cf.ac.uk/Dave/Multimedia/node149.html
So I presume that when we hear recordings of dolphin speech, they are
recorded at these higher sampling rates, or certainly for purposes of
scientific study they are.
Then perhaps the problem is that our human hearing can not adapt to the
amount of date contained in the audio at these high sampling rates, or
their rate of modulation.
So instead of using our audio sense to interpret dolphin speech why not
use a sense that operates at (much) higher frequencies? I'm thinking of
our visual sense. I suggest associating the sounds in dolphin speech
with colors. To represent intensity of the sound you could use the
brightness of the color but I think this would be better represented by
elevation, that is louder sounds would be projected higher on a screen.
The idea is to use our ability to detect recurring patterns visually in
color and form as the means to interpret dolphin speech. There are many
different ways this could be implemented. In fact visual artists might
be the best people to ask about the best ways to implement this and to
be able to "read" the messages produced.
Bob Clark
Test6.zip (89.9 KB)
http://physicsforums.com/attachment.php?attachmentid=4619
test6-8khza.zip (86.7 KB)
http://physicsforums.com/attachment.php?attachmentid=4620
******************************************
Newsgroups: alt.animals.dolphins, rec.arts.sf.science,
sci.anthropology, sci.cognitive, sci.astro.seti
From: rgcl...@my-deja.com (Robert Clark)
Date: 20 Jul 2001 21:46:15 -0700
Local: Sat, Jul 21 2001 12:46 am
Subject: Communicating with dolphins.
The recent news of dolphins having the ability of self-recognition in
mirrors previously believed to be restricted to humans and the great
apes reminded me of a suggestion of Carl Sagan to demonstrate the
communication abilities of dolphins.
Dolphins recognize themselves in mirror
http://www.usatoday.com/news/science/biology/2001-05-01-dolphin-mirror.htm
Mirror self-recognition in the bottlenose dolphin: A case of cognitive
convergence
Proc. Natl. Acad. Sci. USA, Vol. 98, Issue 10, 5937-5942, May 8, 2001
"The ability to recognize oneself in a mirror is an exceedingly rare
capacity in the animal kingdom. To date, only humans and great apes
have shown convincing evidence of mirror self-recognition. Two
dolphins were exposed to reflective surfaces, and both demonstrated
responses consistent with the use of the mirror to investigate marked
parts of the body. This ability to use a mirror to inspect parts of
the body is a striking example of evolutionary convergence with great
apes and humans."
http://www.pnas.org/cgi/content/full/98/10/5937 [full text]
An earlier similar experiment is also available online:
Evidence of self-awareness in the bottlenose dolphin
(Tursiops truncatus)
"Conclusion
"No single test presented here proves self-recognition in bottlenose
dolphins. The tests were developed mainly from primate research
paradigms, and their limitations for interpretations of dolphin
behavior are apparent. Nevertheless, the data taken together make a
compelling case for self-recognition in this species. Four of five
dolphins apparently examined their marks in a mirror; most brought
objects to the mirror and played with them in front of it, even moving
the object back when it drifted out of view; and most of the
mirror-mode television tests designed to distinguish self-examination
from social behavior suggested self-examination. Not only did dolphins
attend to their mirror (or television) images less than 1% of the time
as compared to 100% for real dolphins, but they engaged in different
behavior with mirrors than they did with other dolphins. The results
obtained in the experiments presented here are consistent with the
hypothesis that these animals are using the mirror to examine
themselves. More definitive results, however, will have to come from
methodologies developed specifically for dolphins."
http://planet-hawaii.com/earthtrust/delbook.html [full text]
Sagan wrote about having visited a dolphin research center as part of
his research in SETI communication. In his book, _The Cosmic
Connection_, first published 1973, he suggested a means to test the
idea that dolphins can communicate complex information among
themselves:
"Dolphin anecdotes make marvelous cocktail party accounts, an
unending source of casual conversation. One of the difficulties that I
discovered with research into dolphin language and intelligence was
precisely this fascination with anecdote; the really critical
scientific tests were somehow never performed.
"For example, I repeatedly urged that the following experiment be
done: Dolphin A is introduced into a tank that is eqipped with two
underwater audio speakers. Each hydrophone is attached to an automatic
fish dispenser catering tasty dolphin fare. One speaker plays Bach,
the other plays Beatles. Which speaker is playing Bach or Beatles (a
different composition each time) at any given moment is determined
randomly. Whenever Dolphin A goes to the appropriate speaker - let us
say the one playing Beatles - he is rewarded with a fish. I think
there is no doubt that any dolphin will - because of his great
interest in, and facility with, the audio spectrum - be able soon to
distinguish between Bach and Beatles. But that is not the significant
part of the experiment. What is significant is the number of trials
before Dolphin A becomes sophisticated - that is, always know that if
he wishes a fish he should go to the speaker playing Beatles.
"Now Dolphin A is separated from the speakers by a barrier of plastic
broad-gauge mesh. He can see through the barrier, he can smell and
taste through it, and most important, he can hear and "speak" through
it. But he cannot swim through it. Dolphin B is then introduced into
the area of the speakers. Dolphin B is naive; that is he has had no
prior experience with underwater fish dispensers, Bach, or Beatles.
Unlike the well-known difficulty in finding
"naive" college students with whom to perform experiments on cannibis
sativa [ahem], there will be no difficulty finding dolphins lacking
extensive experience with Bach and Beatles. Dolphin B must go through
the same learning procedure as did Dolphin A. But now each time that
Dolphin B (at first randomly) succeeds, not only does the dispenser
provide him with a fish, but a fish is thrown to Dolphin A, who is
able to witness the learning experience of Dolphin B. If Dolphin A is
hungry, it is distinctly to his advantage to communicate what he knows
about Bach and Beatles to Dolphin B. If Dolphin B is hungry, it is to
his advantage to pay attention to the information that Dolphin A may
have. The question, therefore is: Does Dolphin B have a steeper
learning curve than Dolphin A? Does he reach the plateau of
sophistication in fewer trials or less time?
"If such experiments were repeated many times and it were found that
the learning curves for Dolphin B were in a statistically significant
sense always steeper than those of Dolphin A, communication of
moderately interesting information between two dolphins would have
been established. It might be a verbal description of the difference
between Bach and the Beatles - to my mind, a difficult but not
impossible task - or it might simply be the distinction between right
and left in each trial, until Dolphin B catches on. This is not the
best experimental design to test dolphin-to-dolphin communication, but
it is typical of a large category of experiments that could be
performed. To my knowledge and regret, no such experiments have been
performed with dolphins to date."
_The Cosmic Connection_
Ch. 24., "Some of my best friends are dolphins", pp. 177-178, 2000
edition.
Sagan wrote this in 1973. Anyone know if such experiments have been
performed since then?
Bob Clark
*******************************************
Newsgroups: alt.animals.dolphins, rec.arts.sf.science,
sci.anthropology, sci.cognitive, sci.astro.seti
From: rgcl...@my-deja.com (Robert Clark)
Date: 24 Jul 2001 16:51:36 -0700
Local: Tues, Jul 24 2001 7:51 pm
Subject: Re: Communicating with dolphins.
I was informed via email of research by Bastian and by Markov
on the question of dolphin communication:
J. Bastian (1967)
The transmission of arbitrary environmental information between
bottlenosed dolphins.
in: R.G. Busnel (ed): Animal sonar systems - Biology and bionics,
vol 2, pp. 807-873
NATO Advanced Study Institute / Lab. de Physiologie Acoustique,
France
A.V. Zanin, V.I. Markov and I.E. Sidorova (1990)
The ability of bottlenose dolphins, Tursiops truncatus, to report
arbitrary information
in: J.A. Thomas and R.A. Kastelein (eds): Sensory Abilities of
Cetaceans - Laboratory and Field Evidence, pp. 685-697
NATO ASI Series, Series A: Life Sciences, vol 196, Plenum Press,
London and New York
After a web search I found a site by Kenneth W. LeVasseur that
describes this research:
Dolphin Intelligence and the Captivity Issue
http://whales.magna.com.au/POLICIES/levasseur/
To implement an experiment of the type Sagan proposes it would
probably be better to test for simpler discrimination tasks at
first than the one he mentions. However, I did find on the Dolphin
Research Institute site an experiment that suggests dolphins
might be able to make the complex melody form discrimination
described by Sagan. I discuss it below.
In the email I received, it was suggested that in the experiments
of Bastain and Markov there was simple "binary information"
exchange. I presume this means communicating something like a "yes"
or a "no" to the other dolphin. Say for example when Dolphin B
swims by the correct speaker, Dolphin A lets out an enthusiastic
squeak but gives a muted response or no response when it swims by
the other speaker. Another way to signal in a simple way would be
for Dolphin A to position itself in front of the correct speaker
if the speakers were aligned in front of the mesh screen.
I think there should be ways to overcome these objections. One
possibility would make a success a little more difficult by not
releasing a fish unless a dolphin goes first to the correct speaker
and does not visit the incorrect speaker. This would take a longer
time to train but I think it should be doable.
Also the speakers should not be placed so that Dolphin A can
signal which is the right one by positioning itself. You should
also increase the number of speakers the dolphin has to decide
from rather than two. Also to increase the dolphins desire to
visit a speaker you could have a fish visible and with its scent
detectable attached to each speaker, only the fish is not released
unless the dolphin visits the correct speaker.
Then you could observe whether Dolphin B is able to directly go
to the correct speaker. If it swims around but does eventually get
to the right speaker and in a faster time than Dolphin A that might
suggest it was yes/no information being communicated. Note that
Dolphin A remembering how long it took for its own accomplishment
of the task would have motivation for communicating directly which
speaker to go to.
Note that a success in fast learning for Dolphin B could mean
the required discrimination was communicated or it could mean
the number of the speaker to go to was communicated. However,
even if it was number communicated I think that in itself would
be significant.
You would also want to do the experiment where some other specific
behaviors need to be performed to receive the fish. One example
might be: "bite the ball on top of the correct speaker." You would
want the behavior to be something that dolphins would naturally be
able to communicate if they did indeed have a natural language.
If dolphins communicate naturally then you would expect the correct
response would be communicated immediately. But in the Bastian
experiment, it took several trials to get the correct response.
LeVasseur makes the argument this was because they were quite young
when captured. In the Markov experiments they did use older dolphins,
but from the description it does not appear the communication was
immediate here either. It's not made clear here whether the dolphins
used were from a common group that would be expected to communicate
if they indeed did have a natural language. The situation may be
analogous to that of human beings where separate groups develop
different languages. In future experiments it may be best to
insure the dolphins are from a common group. Nevertheless, Markov
et.al. did conclude that dolphins do have a complex language.
Also, the research by Markov seems to show there is less
communication under stressful conditions. Perhaps the experiments
should be performed in the wild as well as ensuring that the dolphins
are from a common group. You could probably train one dolphin in the
discrimination task when it temporarily, voluntarily separates from
one or more members of the group, suspending training when the second
dolphin you want to train comes within view of the training. However,
the strategy of training another dolphin while the first dolphin
observes would be more difficult to implement without keeping the
first dolphin in an enclosure. Perhaps one possibility in the wild
would be like if there is an area separated from the open sea by a
rocky crag. It takes some minutes to swim around the crag, but the
dolphins are familiar with it and do it commonly. You carve an
opening in the crag and place a screen across the opening so that
a dolphin that happened to swim to the separated area would now be
able to view his companions in the open sea.
In some experiments, you might want it that when Dolphin B is
being trained, Dolphin A is not able to see the position of the
speakers so that the information communicated has to be of a more
complex character to identify the correct speaker to Dolphin B.
However, I recall reading that a dolphin can "read" the echolocation
signals of another dolphin. So you might need to insure this
information also can not be communicated.
The page from the Dolphin Research Institute that suggests dolphins
might be able to distinguish melodic form is at:
Hearing Capabilities
"Recognizing Different Melodies
"Dolphins can recognize different melodies (Ralston & Herman, 1995).
They possess an apparently unique ability among non-human animals to
recognize familiar melodies across octave changes.
"In contrast, songbirds appear to regard such changes as different
melodies, focusing on the absolute pitch of the various notes rather
than the relative changes in pitch."
http://www.dolphin-institute.org/research/dolphinres.html#Dolphin
Hearing Capabilities
This is discussed in:
Ralston, J. V. & Herman, L. M. (1995). Perception and generalization
of frequency contours by a bottlenose dolphin (Tursiops truncatus).
Journal of Comparative Psychology, 109, 268-277.
A nice review of the research on the dolphin communication question
is on the page:
EARTHTRUST & SEA LIFE PARK HAWAII'S HUMAN-DOLPHIN COMMUNICATION
PROJECT
http://neoteny.eccosys.com/~bigtwin/MOON/moon02.html
On his page, Kenneth LeVasseur also suggests using other methods
than operant conditioning with fish rewards to train the dolphins:
A THIRD PHASE ALTERNATIVE TO DOLPHIN CAPTIVITY
http://whales.magna.com.au/POLICIES/levasseur/levass3b.html
Bob Clark
**************************************************
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