Thread: Ultrasound to induce Lucid Dreams?

Originally Posted by Ailos

Haha, well if you wanna shell out that kind of money, be my guest. I'm just as interested as anyone else =]

Hey Ailos, sorry to bother you but what does low intensity "pulsed" ultrasound mean?

Secondly, is "pulsed" ultrasound what hey used in the experiment?

Pulsed refers to the length of time the ultrasound was active. I believe in this experiment the pulse was the length of mere milliseconds, or less, but it should specify the length in the study. So the ultrasonic frequency has nothing to do with the pulse length. This is important since the focused vibrations generate heat, and consequently can damage tissue if it becomes exposed for too long (higher ultrasonic frequencies and higher amplitudes [power] are actually used to destroy tissues within the body).

I'm thinking the effects of neural excitation had lasted longer than the actual pulse length, but how long this latent effect lasted I'm not clear on.

And I do believe I read that they had, in fact, used pulsed ultrasound at a variety of pulse lengths.

Ive read the study man time over and from what Ive read the Ultrasonic Transducers had the following Properties.

Frequency: 0.44 MHz
Tone Burst Duration (TBD): 22.7 microseconds
Cycles per tone-burst (c/tb): 10
Pulse Repetition Frequency (PRF): 0-100Hz linear sweep over a 5 second period
Number of tone burst per stimulus (Ntb): 250
P-P Square Wave amplitude: 500 mV

Im having trouble understanding the last three, can you help explain what they mean/refer to.

Thanks Ailos

Good job finding that.

Yeah, the last three:

"Pulse Repetition Frequency" refers to how many pulses (of length 22.7 microseconds, with a tonal frequency of .44Mhz) there are per second. The 0-100Hz linear sweep means that this repetition frequency "sweeps", or increases linearly, from 0 Hz to 100 Hz over the period of 5 seconds.

"Number of tone bursts per stimulus" refers to how many pulses (of length 22.7 microseconds, with a tonal frequency of .44Mhz) occur over the 5-second repetition frequency sweep.

The P-P Square Wave amplitude is how "big" the square wave is (a square wave is basically on-off-on-off with little to no in-between, unlike a sine-wave which is gradual in its gain and loss). The P-P is peak to peak I believe, meaning that the lower peak (trough) is 500mV less than the upper peak (crest).

Hope that helps!

Originally Posted by Ailos

Good job finding that.

Yeah, the last three:

"Pulse Repetition Frequency" refers to how many pulses (of length 22.7 microseconds, with a tonal frequency of .44Mhz) there are per second. The 0-100Hz linear sweep means that this repetition frequency "sweeps", or increases linearly, from 0 Hz to 100 Hz over the period of 5 seconds.

"Number of tone bursts per stimulus" refers to how many pulses (of length 22.7 microseconds, with a tonal frequency of .44Mhz) occur over the 5-second repetition frequency sweep.

The P-P Square Wave amplitude is how "big" the square wave is (a square wave is basically on-off-on-off with little to no in-between, unlike a sine-wave which is gradual in its gain and loss). The P-P is peak to peak I believe, meaning that the lower peak (trough) is 500mV less than the upper peak (crest).


Hope that helps!

Thanks a lot Ailos.

So they where using a square waves and not sine wave?

Can ultrasonic transducers produce sqare waves or do we have to modify it or build a custom one?

The waveform isn't produced by the transducer, whether it be square, sine, or triangle.

Electrical waveforms are generally generated by circuits called "function generators", the simplest being made with the 555 chip (which produces square waves at a maximum frequency of around .16 Mhz). The function generator that these scientists used was a bit more expensive than a 15 cent 555 chip, but it had far more options than were needed. You can make a 1 Mhz function generator for cheap (see one of my previous posts for a link).

The waveforms are likely fed to a high-frequency power transistor as to prevent damage to the function generator from too much current draw. However, since the one they used was one of the more fancy models, it may have included higher power levels.

Anyways, the waveform then goes to the transducer, where it is transduced into mechanical energy. Square waves are used with piezoelectric elements because they function better under on-off waveforms as opposed to those with varying levels of amplitude (which is why you don't use them for computer speakers or headphones).

As far as the transducer goes, as long as it can handle the required frequency, it doesn't have any effect on the waveform that is fed to it.

This may seem like a ridiculously stupid question, but can i use an ultrasonic toothbrushes instead of having to buy a custom ultrasonic transducer alone.

The Ultrasonex Ultrasonic Toothbrush works at 1.6 MHz.

http://www.youtube.com/watch?v=xQ1IB7QY80c

Is there anything wrong with using a Ultrasonic Toothbrush vs a custom Ultrasonic Transducer?

Thanks