United States Patent |
4,191,175
|
Nagle
|
March 4, 1980
|
Method and apparatus for repetitively producing a noise-like audible signal
Abstract
A digital pulse generator and shift register repetitively produce bursts of
digital pulses at a first adjustable repetition frequency. The repetition
frequency of the pulses in each burst is also adjustable. A pink noise
filter accentuates the lower burst frequency components near 7 hz and
substantially attenuates all frequency components of the bursts above a
first cut-off point near 10 Khz. A tunable band pass amplifier having a
center frequency adjustable over a preselected range of frequencies
optimally detectable by the average human ear accentuates the pink noise
filter output near 2.6 Khz. The tunable amplifier drives an audible signal
source with noise-like pulses of varying amplitudes and frequency
components. A low pass amplifier may be connected to the pink noise filter
to generate a train of pulses having a repetition frequency near 7 hz
which pulses a light source in synchronism with the audible noise-like
signal.
Inventors:
|
Nagle; William L. (c/o Seidel Gonda & Goldhammer, P.C. 600 Three Penn Center, Philadelphia, PA 19102)
|
Appl. No.:
|
870050 |
Filed:
|
January 16, 1978 |
Current U.S. Class: |
600/27; 984/341; 984/DIG1 |
Intern'l Class: |
A61B 019/00 |
Field of Search: |
128/1 C,2.1 B
331/78
|
References Cited
U.S. Patent Documents
3576185 | Apr., 1971 | Schulz et al. | 128/1.
|
4034741 | Jul., 1977 | Adams et al. | 128/1.
|
Foreign Patent Documents |
1088607 | Oct., 1967 | GB | 128/1.
|
Other References
Faran "The General Radio Experimenter" vol. 36, No. 7, Jul., 1962, pp. 4-5,
331/78.
|
Primary Examiner: Kamm; William E.
Attorney, Agent or Firm: Seidel, Gonda, Goldhammer & Panitch
Claims
I claim:
1. Apparatus for repetitively producing a noise-like audible signal,
comprising:
an audible signal source,
means for repetitively generating at a first adjustable repetition
frequency bursts of digital pulses, said pulses within each burst having a
second higher adjustable repetition frequency,
pink noise filter means connected to said pulse burst generating means for
substantially attentuating all frequencies of said repetitive bursts of
digital pulses above a first cutoff frequency and for accentuating a
preselected range of lower frequencies.
tunable band pass filter means connected to said pink noise filter means
for repetitively generating noise-like pulses of varying amplitudes, said
tunable band pass filter means having a center frequency which is
adjustable over a preselected range of frequencies which correspond to the
frequencies optimally detectable by the average human ear, said noise-like
signal having a frequency component accentuated at approximately said
center frequency, and
means connected to said tunable band pass filter means for driving said
audible signal source.
2. The apparatus according to claim 1 including a light source and low pass
filter means connected to said pink noise filter means for generating a
train of pulses having a repetition frequency in the range of
approximately 0.5 hz to 12 hz, and means connected to said low pass filter
means for driving said light source at said 0.5 hz to 12 hz repetition
frequency.
3. The apparatus according to claim 1 wherein said means for repetitively
generating said bursts of digital pulses includes a digital pulse
generator for generating a train of digital pulses at said second
adjustable frequency, a shift register connected thereto, and a logical
gate connected to said shift register for repetitively resetting said
shift register at said first adjustable frequency.
4. The apparatus according to claim 3 wherein said pink noise filter means
is a passive RC filter and said first cut-off frequency is approximately
10 Khz.
5. The apparatus according to claim 3 wherein said first adjustable
frequency is approximately 7 hz, said second adjustable frequency is
approximately 230 Khz, said preselected range of lower frequencies is
approximately 0-50 hz, and said center frequency is approximately 2.6 Khz.
6. Apparatus for repetitively producing a noise-like audible signal,
comprising:
a light source and an audible signal source,
means for repetitively generating at a first adjustable frequency bursts of
digital pulses, said pulses within said burst having a second higher
adjustable repetition frequency,
pink noise filter means connected to said pulse burst generating means for
substantially attenuating all frequencies of said repetitive bursts of
digital pulses above a first cut-off frequency and for accentuating a
preselected range of lower frequencies,
tunable band pass filter means connected to said pink noise filter means
for repetitively generating noise-like pulses of varying amplitude, said
tunable band pass filter means having a center frequency which is
adjustable over a preselected range of frequencies which correspond to the
frequencies optimally detectable by the average human ear, said noise-like
signal having a frequency component accentuated at approximately said
center frequency,
low pass filter means connected to said pink noise filter means for
generating a train of pulses having a repetition frequency within said
preselected range of lower frequencies, and
means connected to said tunable band pass filter means and said low pass
filter means for driving said light source with said train of pulses
having a repetition frequency preselected range of lower frequencies and
for simultaneously driving said audible signal source with said noise-like
train of pulses.
7. A method of repetitively producing a noise-like audible signal,
comprising:
repetitively generating at a repetition first frequency bursts of digital
pulses, said pulses within each burst having a second higher repetition
frequency,
generating a first repetitive signal based on said repetitive bursts of
digital pulses wherein all frequencies of said repetitive bursts above a
first cut-off frequency are substantially attenuated and a preselected
range of lower frequencies is accentuated,
generating a second repetitive noise-like signal based on said first
repetitive signal wherein all frequencies within a preselected band pass
within the range of frequencies optimally detectable by the average human
ear are substantially accentuated, said second repetitive noise-like
signal having a strong pulsating component at a preselected frequency
within said band pass, and
driving an audible signal source with said second repetitive noise-like
signal.
8. The method according to claim 7 including generating a train of pulses
based on said first repetitive signal having a frequency in the range of
approximately 0.5 hz to 12 hz, and driving a light source with said train
of pulses having a 0.5 hz to 12 hz repetition frequency.
9. The method according to claim 7 wherein said strong pulsating frequency
component has a frequency of approximately 2.6 Khz.
10. A method of repetitively producing a noise-like audible signal,
comprising:
repetitively generating at a repetitive first frequency bursts of digital
pulses, said pulses within each burst having a second higher repetition
frequency,
generating a first repetive signal based on said repetitive bursts of
digital pulses wherein all frequencies of said repetitive bursts above a
first cut-off frequency are substantially attenuated, and a preselected
range of lower frequencies is accentuated
generating a second repetitive noise-like signal based on said first
repetitive signal wherein all frequencies within a preselected band pass
within the range of frequencies optimally detectable by the average human
ear are substantially acccentuated, said second repetitive signal having a
strong pulsating component at a preselected frequency within said band
pass, and
generating a third repetitive signal based on said first repetitive signal
having a frequency in the range of approximately 0.5 hz to 12 hz, and
simultaneously driving a light source with said third repetitive signal and
an audible signal source with said second repetitive noise-like signal.
Description
BACKGROUND OF THE INVENTION
The present invention is directed to a method and apparatus for producing a
noise-like signal for inducing a hypnotic or anesthetic effect in a human
being. The invention also has application in crowd control consciousness
level training (biofeedback) and heart rate detection training
(biofeedback). The invention may also be used in creating special musical
effects.
The invention is particularly directed to the creation of a filtered
repetitive noise-like signal alone or in combination with a repetitive
visible signal. The audible signal has a pronounced effect on the human
central nervous system.
Devices are known in the prior art for producing audible signals alone or
in combination with a visible signal for inducing sleep. For example, see
U.S. Pat. No. 3,576,185 to Shulz et al. which discloses a device for
generating an audible pulsating sinusoidal signal and a visible signal in
synchronism. Other devices which employ white noise sources for inducing
sleep are also known. For example, see U.S. Pat. No. 3,835,833 to Limoge.
Still other devices are known wherein sleep is induced by pulsing a light
source at relatively low frequencies. See U.S. Pat. No. 3,388,699 to Webb
et al. It is also known that the nervous system can be stimulated by
amplitude modulated audible carrier signals at the alpha and theta
frequencies of the brain. See U.S. Pat. No. 3,753,433 to Bakerich et al.
(electroencephalophone feedback system).
None of these devices employ filtered repetitive noise-like audible signals
to influence the human central nervous system. Such signals, however, are
remarkably effective in changing states of consciousness or inducing
hypnotic, anesthetic or sleep-like states.
An advantage of the invention is that it provides a filtered repetitive
noise-like audible signal extremely effective in influencing the human
central nervous system.
A further advantage of the invention is that it is versatile in that the
audible signal frequencies can be adjusted to match the sensitivity of the
central nervous systems of different individuals.
A further advantage of the invention is that it is of simple design and
construction and relatively easy to trouble shoot and repair.
Other advantages appear hereinafter.
BRIEF SUMMARY OF THE INVENTION
Method and apparatus for repetitively producing a noise-like audible
signal. Bursts of digital pulses are repetitively generated at a first
frequency. The repetition frequency of the digital pulses within each
burst is much higher than the burst frequency. The lower frequencies of
the bursts near 7 hz are accentuated and the frequencies which lie above a
first cut-off point are substantially attenuated by a pink noise filter.
The frequencies of the bursts in an adjustable band pass preferably
centered near 2.6 Khz are then accentuated by a tunable band pass
amplifier. The output of the tunable band pass amplifier is a repetitive
noise-like signal which drives an audible signal source. The 7 hz
frequency component of the pulse bursts at the pink noise filter out-put
may be further accentuated by a low pass amplifier which drives a light
source.
For the purpose of illustrating the invention, there is shown in the
drawings a form which is presently preferred; it being understood,
however, that this invention is not limited to the precise arrangements
and instrumentalities shown.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a block diagram of the apparatus of the present invention.
FIGS. 2A and 2B comprise an electrical schematic of the apparatus shown in
FIG. 1.
FIG. 3 is a diagram of certain waveforms produced by the apparatus.
DETAILED DESCRIPTION OF THE INVENTION
Referring to FIG. 1, wherein like numerals indicate like elements, there is
shown an apparatus 10 for generating a repetitive noise-like aubible
signal alone or in combination with a visible signal for inducing a
hypnotic, anesthetic or sleep-like state in an individual in accordance
with the invention. A pulse train generator 12 repetitively generates
bursts of digital pulses A. See FIGS. 1 and 3. Preferably, the repetition
frequency of the bursts f1 is variable between approximately 0.5 hz and 12
hz. The repetition frequency f2 of the pulses within a burst is adjustable
between approximately 15 Khz and 388 Khz.
The output of the pulse train generator 12 is passed through a pink noise
filter 14 which is a relatively wide low pass filter. The pink noise
filter 14 passes all frequencies between approximately 0 hz and 10 Khz,
substantially attentuating all higher frequencies. For purposes of
description herein, the 10 Khz frequency is regarded as the filter cut-off
point.
The ouput of the pink noise filter 14 has a spectral content between
approximately 0 hz and 10 Khz with the lower frequency components,
preferably approximately 0 hz to 50 hz, being accentuated. This output
signal is a repetitive noise-like signal having relatively narrow
frequency band width compared to white noise. The output of the pink noise
filter 14 is processed by an audible signal channel 16 and a visible
signal channel 18. The audible signal channel 16 produces a repetitive
noise-like signal having a frequency spectrum accentuated near 7 hz and
2.6 Khz as described more fully below. The visible signal channel 18
produces a relatively low frequency (near 7 hz) repetitive light signal
which enhances the effect of the noise-like audible signal.
The audible signal channel 16 includes a tunable band pass amplifier 20
with an adjustable center frequency which is set between approximately 1.0
Khz and 7 Khz corresponding to the range of frequencies optimally
detectable by the average human ear in accordance with the well-known
Fletcher-Munson equal loudness contours. See FIG. 3.
The output of the tunable band pass amplifier 20 is passed through a fixed
band pass amplifier 22 which as a fixed center frequency of approximately
2.6 Khz. The output of the fixed band pass amplifier 22 is amplified by a
power amplifier 24. The power amplifier drives a pair of headphones 26 or
other audible transducer such as a loudspeaker. The output of the power
amplifier 24 is a repetitive noise-like signal consisting of a train of
varying amplitude pulses. The spectral content of the noise-like signal at
the output of amplifier 24 is accentuated at the 7 hz burst frequency and
the 2.6 Khz center frequency. The signal includes the remaining
frequencies passed by the pink noise filter 14 but attenuated according to
the characteristics of the band pass amplifier. The noise-like signal has
a unique spectral content which simulates audible noise or hiss roughly
matched to the sensitivity of the average human ear.
The visible signal channel 18 includes a pair of low pass amplifiers 28 and
30. The low pass amplifier 28 passes all frequencies between approximately
0 hz and 65 hz, substantially attenuating all higher frequencies.
Frequencies between approximately 0 hz and 20 hz are accentuated by the
low pass amplifier 28. The output B of the amplifier is a repetitive pulse
signal having rounded rising and falling edges. See FIG. 3. The output of
the low pass amplifier 28 is shaped by low pass amplifier 30 to sharpen
the rise and fall times of the pulses generated by amplifier 28 while
preserving the accentuated frequency components between approximately 0
hz-20 hz. See waveform C in FIG. 3.
The output of low pass amplifier 30 drives a Schmitt trigger circuit 32.
The Schmitt trigger circuit 32 squares the output of amplifier 30 and
drives a conventional diac/triac section 34 via opto-isolator 36. The
diac/triac section operates a light source 38 at approximately the 7 hz
burst frequency.
If desired, the visible signal channel 18 may be omitted. It is preferred,
however, that the individual be exposed to both the repetitive noise-like
signal carried on earphones 26 as well as the relatively low frequency
visible signal generated by light source 38.
A preferred configuration of the electrical components shown in FIG. 1 is
illustrated in FIGS. 2A and 2B. A precision timer 40 such as the SN 52555
timer is connected to operate in the astable mode. See FIG. 2A.
Conventional pin numbers for the timer are designated within block 40. Pin
3 is the clock or output terminal.
The output of timer 40 clocks the shift registers 42 and 44. Shift
registers 42 and 44 are SN 74164 8 bit parallel out serial shift registers
connected in tandem to create a 16 bit register. Conventional pin numbers
for the shift registers are designated within blocks 42 and 44. Pins 1 and
2 are the serial inputs. Pin 8 is the clock input. Pin 13 is the 8th or
last bit of each shift register. Pin 12 is the 7th or next to last bit of
each shift register. Pin 3 is the first bit of the shift register.
The first bit of shift register 42 and the 7th bit of register 44 are
sensed by an Exclusive OR gate 46. Exclusive OR gate 46 may be a SN 7486
gate. Conventional pin numbers are designated within gate symbol 46.
The serial input to shift register 42 is regulated by the Exclusive OR gate
46. The gate 46 senses the first and 15th bits of the tandem shift
register connection and toggles the serial input at the rate of the clock
output from timer 40. When the first and 15th bits of the shift register
are the same, the Exclusive OR gate 46 clamps the serial input of the
shift register. As a result, the 8th bit of shift register 44 (the last
bit of the tandem connection) does not change. This marks the end of each
burst of pulses on line A. The clock output of timer 40 however, continues
to shift data bits through the tandem connection. Eventually, bit 1 of
shift register 42 and bit 8 of shift register 44 become complements and
another burst of pulses is generated on line A. The timer 40 and shift
registers 42 and 44 are free-running. Accordingly, the pulse bursts are
continuously repeated at a regular rate (repetition frequency).
The repetition frequency of the pulses within each burst may be varied by
means of a rate potentiometer 48. This has the effect of varying the
repetition frequency of the clock output of timer 40 and, therefore, the
frequency at which the bursts themselves are generated. The variation of
the burst repetition frequency with the repetition frequency of the clock
output of timer 40 is given in Table I below.
Table I
______________________________________
Repetition Frequency
f2 of Clock Output of
Repetition Frequency f1
Timer 40 in Khz of Pulse Bursts in hz
______________________________________
15 0.5
163 5.0
182 5.5
195 6.0
215 6.5
230 7.0
250 7.5
266 8.0
293 9.0
333 10.0
364 11.0
388 12.0
______________________________________
The output of generator 12 is fed to the pink noise filter 14. The gain
characteristic of the pink noise filter 14 shown in FIG. 2A is given in
Table II below.
Table II
______________________________________
Relative
Frequency in hz Gain (1 volt input)
______________________________________
0-50 1.0
100 0.8
250 0.6
500 0.4
850 0.3
2000 0.2
6000 0.1
______________________________________
The output of the pink noise filter 14 is ac coupled to the input of
tunable band pass amplifier 20 in the audible signal channel. In addition,
the output of the pink noise filter is fed to the input of low pass
amplifier 28 in the visible signal channel.
The tunable band pass amplifier 20 includes an operational amplifier 50 of
the LM 3900 type or equivalent (such as the SN 72L044) connected as an
active band pass filter. The tunable band pass amplifier has an adjustable
center or peak frequency which may be shifted by means of a tune
potentiometer 52. The gain of the amplifier as a function of the center
frequency set by tune potentiometer 52 is given in Table III below.
Table III
______________________________________
Center Frequency Relative
in hz Gain (1 volt input)
______________________________________
600 0.8
1000 1.5
1500 2.2
2000 2.2
2600 2.9
3000 3.0
3500 3.2
4000 3.2
5000 3.4
6000 3.5
7000 3.5
______________________________________
The output of the tunable band pass amplifier 20 is fed to the fixed band
pass amplifier 22 comprising an operational amplifier 54 of the LM 3900
type connected as an active band pass filter. The spectral characteristic
of the fixed band pass amplifier is given in Table IV below:
Table IV
______________________________________
Relative
Frequency in hz Gain (1 volt input)
______________________________________
600 0.8
1000 1.8
1500 3.0
2000 3.0
2600 3.9
3000 3.2
3500 2.3
4000 1.6
5000 0.9
6000 0.5
7000 0.3
______________________________________
The center or peak frequency of the fixed band pass amplifier 22 is
approximately 2.6 Khz. The 2.6 Khz frequency is of particular importance
as it is within the most sensitive range of human hearing as indicated by
the Fletcher-Munson equal loudness contours. See FIG. 3. A 2.6 Khz audible
signal is known to induce strong physiological effects. See UCLA Weekly,
Volume 7, No. 8 (Nov. 29, 1976) (2.6 Khz frequency produced by a whistling
bottle). Accordingly, this frequency is emphasized in the repetitive
noise-like signal generated at the output of band pass amplifier 22.
The output of band pass amplifier 22 is amplified by power amplifier 24.
Power amplifier 24 includes an operational amplifier 56 of the LM 3900
type. The volume of the signal generated by amplifier 56 may be adjusted
by means of a volume potentiometer 58.
The repetitive noise-like signal appearing at the output of amplifier 56
includes all frequency components between approximately 0 hz and 10 Khz
(the nominal cut-off point of pink noise filter 14) with particular
emphasis on the 2.6 Khz frequency. The signal includes the accentuated 7
hz burst frequency. The effectiveness of the signal in inducing
physiological response is believed to be due to the noise-like nature of
the signal which is simulated by the repetitive frequency components
between approximately 0 hz and 10 Khz and the emphasized 2.6 Khz
frequency. The signal simulates hiss having a spectral range corresponding
to the Fletcher-Munson range (0 hz-10 Khz) with pronounced pulsating
components near 2.6 Khz.
The output of the pink noise filter 14 may also be used to generate a low
frequency light signal via the visible signal channel 18 as already
indicated. The output of the pink noise filter is fed to the low pass
amplifier 28 comprising an operational amplifier 60 of the LM 3900 type
connected as an active low pass filter. The low pass filter 28 frequency
characteristic is given in Table V below.
Table V
______________________________________
Relative
Frequency in hz Gain (1 volt input)
______________________________________
0-10 1.0
17 0.8
23 0.6
35 0.2
65 0.1
______________________________________
The low pass filter 28 accentuates the lower frequencies, 0 hz-20 hz. The
7 hz burst frequency is within the range of frequencies accentuated by the
filter. The output of the filter is ac coupled to the second low pass
amplifier 30 comprising an operational amplifier 62 of the LM 3900 type
also connected as an active low pass filter.
Low pass amplifier 30 squares up the output of amplifier 28 to insure
reliable operation of the Schmitt trigger circuit 32. The Schmitt trigger
circuit 32 includes a SN 74121 monostable multivibrator 64 with Schmitt
trigger input. Conventional pin numbers of the monostable multivibrator
are designated in block 64. Pins 3, 4 and 5 are the inputs. Pins 10 and 11
are connected to the external timing circuit comprising the 10 K resistor
and the 3.3 mf capacitor. Pin 6 is the Q output of the Schmitt trigger
circuit. This output triggers the opto-isolator 36 at the 7 hz burst rate.
The output of the Schmitt trigger circuit controls the diac/triac section
34 via the opto-isolator 36. Opto-isolator 36 may be a CLM 8000 type
isolator.
The diac/triac section 34 includes a diac 66 which controls the gate of a
triac 68. The triac alternately energizes and deenergizes a light source
70 (such as a neon tube) approximately at the 7 hz burst frequency. The
low frequency light pulsations enhance the hypnotic or anesthetic effect
produced by the noise-like audible signal generated by power amplifier 24.
The sensory effect produced by the noise-like audible signal and the low
frequency light pulsations may be further enhanced by driving a pair of
light emitting diodes 72 and 74 by the complementary outputs Q and Q of
the Schmitt trigger circuit. The light emitting diode 72 and 74 may be
secured in place in an eye shade 76 represented in phantom in FIG. 2B. The
light emitting diodes are alternately pulsed, each at the 7 hz burst
frequency.
The invention has been described in terms of various well-known electronic
components such as precision timers, shift registers, Schmitt triggers and
operational amplifiers. The invention is not limited to these particular
devices but covers all equivalents thereof for attaining the same function
and effect described herein.
As noted above, the generation of a repetitive noise-like signal in the
audible signal channel having accentuated spectral components near 2.6 Khz
entails a significant departure from prior art devices which employ broad
band white noise generators or the like. By processing a repetitive burst
of digital pulses through a pink noise filter and tunable and fixed band
pass filters, the invention simulates a relatively narrow band noise (0
hz-10 Khz) with a strong component near 2.6 Khz.
It is preferred that the band pass amplifier 20 have a center frequency
tunable over a range of frequencies corresponding to the most sensitive
frequencies to the human ear as designated by the Fletcher-Munson curves.
Preferably, the center frequency is tuned at approximately 2.6 Khz
although other center frequencies including those between 1 Khz and 7 Khz
may also be satisfactory. Assuming that the tunable band pass amplifier 20
is tuned to the 2.6 Khz center frequency, it will have a band pass
characterisic as indicated in Table VI below.
Table VI
______________________________________
Relative
Frequency in hz Gain (1 volt input)
______________________________________
600-900 0.4
1800 0.6
2200 0.8
2600 1.0
3000 0.8
3200 0.6
3600 0.4
4500 0.2
6000 0.1
______________________________________
The band pass characteristic will vary somewhat as the center frequency is
tuned to frequencies other than 2.6 Khz. The 2.6 Khz setting is, however,
preferred for reasons already indicated.
The present invention may be embodied in other specific forms without
departing from the spirit or essential attributes thereof and,
accordingly, reference should be made to the appended claims, rather than
to the foregoing specification as indicating the scope of the invention.
* * * * *