System and method for anti-phase binocular separation stimulation

Abstract

A system and method for anti-phased binocular stimulation may include a device for determining a target frequency for the stimulus response. The device may output a first visual stimulus to the first eye at a first frequency and a first phase. The device may output a second visual stimulus to the second eye at a second frequency and a second phase. Both the first and second visual stimuli may produce a stimulus response at a target frequency. The first frequency may be half of the target frequency, and the second frequency may be half of the target frequency.

Description

Technical Field

[0001] (Cross - reference to related applications) This application claims the priority and benefit of U.S. Patent Application No. 18 / 132,852, filed on April 10, 2023, and issued as U.S. Patent No. 11,730,975, the content of which is incorporated herein by reference in its entirety.

[0002] This disclosure generally relates to nerve stimulation.

Background Art

[0003] Neural oscillations occur in humans and animals and include rhythmic or repetitive neural activity within the central nervous system. Neural tissue can generate oscillatory activity either by mechanisms within individual neurons or by interactions between neurons. Oscillations can appear as either periodic fluctuations in the membrane potential that can cause postsynaptic neuron oscillatory activation or rhythmic patterns of action potentials. Synchronized activity of groups of neurons can give rise to macroscopic oscillations, which can be observed by sensing the electric or magnetic fields within the brain using techniques such as electroencephalography (EEG), intracranial EEG (iEEG), also known as electrocorticogram (ECoG), and magnetoencephalography (MEG).

Summary of the Invention

Means for Solving the Problems

[0004] According to the systems and methods described herein, nerve stimulation can be provided via antiphased or alternating binocular (e.g., binocular) stimulation, in which separate fields or stimuli are presented or provided to each eye. The systems and methods described herein may use antiphased binocular (i.e., binocular) stimulation at a frequency below the target frequency to produce or provide stimulation at the target frequency. Some systems would only output stimulation at the target frequency in order to provide stimulation at the target frequency. For example, to provide stimulation at a target frequency of 40 Hz, some systems would output stimulation at 40 Hz. In contrast to such systems, it has been observed that providing antiphased or alternating binocular stimulation at a reduced frequency (such as half the target frequency) produces a higher stimulus response at the target frequency compared to providing stimulation at the target frequency, depending on the target frequency of the stimulation and other parameters. Stimulation can modulate, control, or otherwise influence the frequency of nerve oscillations, thereby mitigating or preventing adverse consequences on a cognitive state or cognitive function while providing beneficial effects on one or more cognitive states, cognitive functions, immune systems, or inflammation. For example, the stimulus response to the systems and methods of this technology can treat, prevent, avoid, or otherwise influence Alzheimer's disease or other cognitive or neurological disorders.

[0005] In various cases, when a patient is receiving treatment or, otherwise, auditory or visual stimulation as described herein, the stimulation is often at a targeted frequency or frequency band, or in a specific frequency or frequency band (e.g., within the delta, theta, and / or gamma bands), to stimulate a specific response in the patient's brain (e.g., at a specific frequency and / or in a specific part, region, or field of the patient's brain). Rather than producing stimulation at a targeted or specific frequency, as described below, the systems and methods described herein may provide anti-phased stimulation at related or reduced frequencies, which, due to the nonlinear response of neurons and networks in the brain, provides a combined effect of stimulating the brain at the target frequency. Such implementations and embodiments may result in a higher stimulus response in the patient's brain at the target frequency, which may thereby increase the effectiveness of the treatment.

[0006] In one aspect, this disclosure relates to a method comprising determining a target frequency for a stimulus response using a device. The method comprises outputting a first visual stimulus at a first frequency and a first phase to a first eye using the device. The method comprises outputting a second visual stimulus at a second frequency and a second phase to a second eye using the device. Both the first and second visual stimuli may produce a stimulus response at a target frequency.

[0007] In some embodiments, the first frequency is half the target frequency, and the second frequency is half the target frequency. In some embodiments, the second phase is out of phase with respect to the first phase. In some embodiments, the target frequency is 35-40 Hz. In some embodiments, the sum of the first and second frequencies is equal to the target frequency. In some embodiments, the target frequency is equal to 38 Hz, the first frequency is equal to 19 Hz, and the second frequency is equal to 19 Hz.

[0008] In some embodiments, the device includes one or more first light sources for stimulating a first eye and one or more second light sources for stimulating a second eye. Outputting a first visual stimulus may include controlling one or more first light sources to output light at a first frequency and a first phase. Outputting a second visual stimulus may include controlling one or more second light sources to output light at a second frequency and a second phase. In some embodiments, the device includes a head-wearable device, which includes one or more first light sources located at a first position on the head-wearable device and one or more second light sources located at a second position on the head-wearable device. The first position may correspond to stimulating a first eye when the head-wearable device is worn, and the second position may correspond to stimulating a second eye when the head-wearable device is worn.

[0009] In another aspect, this disclosure relates to a device. The device includes one or more light sources. The device includes one or more processors, one or more processors configured to determine a target frequency for a stimulus response, to output a first visual stimulus at a first frequency and a first phase to a first eye, and to output a second visual stimulus at a second frequency and a second phase to a second eye. Both the first and second visual stimuli may produce a stimulus response at a target frequency.

[0010] In some embodiments, the first frequency is half the target frequency, the second frequency is half the target frequency, and the second phase is out of phase with respect to the first phase. In some embodiments, the target frequency is equal to 38 Hz, the first frequency is equal to 19 Hz, and the second frequency is equal to 19 Hz.

[0011] In yet another aspect, this disclosure covers a system. The system includes one or more light sources. The system includes one or more processors, one or more processors configured to determine a target frequency for a stimulus response, to output a first visual stimulus at a first frequency and a first phase to a first eye, and to output a second visual stimulus at a second frequency and a second phase to a second eye. Both the first and second visual stimuli may produce a stimulus response at a target frequency. [Brief explanation of the drawing]

[0012] The accompanying drawings are not intended to be drawn to scale. Similar reference numbers and symbols in various drawings indicate similar elements. For the purpose of clarity, not all components can be marked in all drawings.

[0013] [Figure 1] Figure 1 is a block diagram of a system for anti-phased binocular stimulation, as illustrated by an exemplary implementation of the present disclosure.

[0014] [Figure 2] Figure 2 illustrates a first graph showing the target frequency and a second graph showing the oscillation states for providing the target frequency, according to an exemplary implementation of the present disclosure.

[0015] [Figure 3] Figure 3 illustrates an embodiment of a head-worn wearable device for providing visual stimuli, according to an exemplary implementation of the present disclosure.

[0016] [Figure 4] Figure 4 illustrates an embodiment of a system for providing visual stimuli, based on an exemplary implementation of the present disclosure.

[0017] [Figure 5] Figure 5 illustrates a lighting system that may be implemented within the system shown in Figure 4, based on an exemplary implementation of the present disclosure.

[0018] [Figure 6] Figure 6 depicts a series of images that illustrate the (actual) measured stimulus responses due to different visual stimulus inputs into a patient, according to an exemplary implementation of the present disclosure.

[0019] [Figure 7] Figure 7 depicts another series of images that illustrate the average stimulus responses across multiple patients due to different visual stimulus inputs, according to an exemplary implementation of the present disclosure.

[0020] [Figure 8A] Figures 8A - 8F depict a series of graphs that illustrate the power spectral density and gain for different types of input stimuli shown in FIGS. 6 and 7, according to an exemplary implementation of the present disclosure. [Figure 8B] Figures 8A - 8F depict a series of graphs that illustrate the power spectral density and gain for different types of input stimuli shown in FIGS. 6 and 7, according to an exemplary implementation of the present disclosure. [Figure 8C] Figures 8A - 8F depict a series of graphs that illustrate the power spectral density and gain for different types of input stimuli shown in FIGS. 6 and 7, according to an exemplary implementation of the present disclosure. [Figure 8D] Figures 8A - 8F depict a series of graphs that illustrate the power spectral density and gain for different types of input stimuli shown in FIGS. 6 and 7, according to an exemplary implementation of the present disclosure. [Figure 8E] Figures 8A - 8F depict a series of graphs that illustrate the power spectral density and gain for different types of input stimuli shown in FIGS. 6 and 7, according to an exemplary implementation of the present disclosure. [Figure 8F] Figures 8A - 8F depict a series of graphs that illustrate the power spectral density and gain for different types of input stimuli shown in FIGS. 6 and 7, according to an exemplary implementation of the present disclosure.

[0021] [Figure 9]Figure 9 is a flowchart illustrating an exemplary method for providing anti-phased binocular stimulation, according to an exemplary implementation of the present disclosure.

[0022] [Figure 10] Figure 10 is a block diagram of an exemplary computer system according to an exemplary implementation of the present disclosure. [Modes for carrying out the invention]

[0023] Detailed explanation Before turning to the diagrams illustrating a particular embodiment in detail, please understand that this disclosure is not limited to the details or methodologies described or illustrated in the description or in the diagrams. Also, please understand that the terminology used herein is for illustrative purposes only and should not be considered limiting.

[0024] According to the systems and methods described herein, nerve stimulation can be provided via antiphased (or out-of-phase, alternating, etc.) binocular-separated (i.e., binocular) stimulation. The systems and methods described herein may produce or provide stimulation at a target frequency using antiphased binocular stimulation at a frequency different from the target frequency (e.g., below or above the target frequency). Some systems would simply output stimulation at the target frequency to provide stimulation at the target frequency. For example, to provide stimulation at a target frequency of 40 Hz, some systems would output stimulation at 40 Hz. In contrast to such systems, it has been observed that providing antiphased binocular or binocular-separated stimulation at a relevant frequency (e.g., half the target frequency) can produce a higher constructive stimulus response at the target frequency compared to providing stimulation at the target frequency (e.g., when binocular-separated stimulation is constructive or combined), for example, when the target frequency is near the flicker fusion threshold. Stimulation can modulate, control, or otherwise influence the frequency of nerve oscillations, thereby mitigating or preventing adverse consequences on one or more cognitive states, cognitive functions, immune systems, or inflammation, while providing beneficial effects on a cognitive state or cognitive function. For example, the stimulus response to the systems and methods of this technology can treat, prevent, avoid, or otherwise influence Alzheimer's disease or other cognitive disorders.

[0025] In various cases, when a patient is receiving treatment or, otherwise, auditory stimulation as described herein, the stimulation is often at a targeted frequency or frequency band, or at a specific frequency or frequency band (e.g., within the delta, theta, and / or gamma bands), to stimulate a response in the patient's brain and / or a specific part of the patient's brain. Rather than producing targeted or specific frequency stimulation, as can be carried out by some systems or solutions as described below, the systems and methods described herein may provide stimulation at relevant frequencies, which, due to the nonlinear responses of neurons and networks in the brain, provide a combined effect of stimulation response at the target frequency. Such implementations and embodiments may result in a higher stimulation response in the patient's brain at the target frequency, which may thereby increase the effectiveness of the treatment.

[0026] Nerve oscillations can be characterized by their frequency, amplitude, and phase. These signal properties can be observed from neural recordings using time / frequency analysis. For example, EEG can measure the oscillatory activity between groups of neurons, and the measured oscillatory activity can be categorized into frequency bands as follows: delta activity corresponds to the frequency band of 0.5–4 Hz, theta activity to the frequency band of 4–8 Hz, alpha activity to the frequency band of 8–13 Hz, beta activity to the frequency band of 13–30 Hz, and gamma activity to the frequency band of 30 Hz and above.

[0027] Neuronal oscillations in different frequency bands can be associated with cognitive states or functions such as perception, behavior, attention, reward, learning, and memory. Neuronal oscillations within one or more frequency bands may be triggered based on the cognitive state or function. Furthermore, neuronal oscillations within one or more frequency bands may have beneficial or harmful effects on one or more cognitive states or functions.

[0028] Neuronal synchronization occurs when an external stimulus of a specific frequency or combination of frequencies is perceived by the brain and triggers neural activity within the brain that results in neuronal oscillations at frequencies proportional to the specific frequency of the external stimulus. Therefore, neuronal synchronization can refer to the synchronization of neural oscillations within the brain using an external stimulus so that the oscillations occur at frequencies corresponding to a specific frequency of the external stimulus. Neuronal synchronization can also refer to the synchronization of neural oscillations within the brain using an external stimulus so that the oscillations occur at frequencies corresponding to harmonics, fractional harmonics, integer ratios, and combinations of a specific frequency of the external stimulus. Specific neural oscillation frequencies can be observed depending on the set of external stimulus frequencies. Neural oscillation frequencies can be caused by nonlinear responses of neurons and networks within the brain and can be predicted by models of neural oscillation and neuronal synchronization. Models may be partially based on equation 1 below, which describes the extent to which stimulus frequencies may be related to target response frequencies.

number

number

number

number

[0029]

[0030] Cognitive functions such as learning and memory involve coordinated activity across dispersed subcortical and cortical brain regions, including the hippocampus, cortical and subcortical association areas, sensory areas, and the prefrontal cortex. Across different brain regions, behaviorally relevant information is encoded, maintained, and retrieved through transient increases in power between neural oscillators and transient increases in synchronization between neural oscillators, reflecting multiple frequencies of activity.

[0031] In particular, oscillatory neural activity in the theta and gamma frequency bands is associated with encoding, maintenance, and retrieval processes in short-term, working, and long-term memory. Evoked gamma activity is associated with working memory and increases scalp recording and intracranial gamma band activity that occurs during working-memory maintenance. Increases in gamma activity power dynamically track the number of items maintained in working memory. Using cortical electroencephalography (ECoG), one study found that increases in gamma power tracked working / memory load in the hippocampus and medial temporal lobe when participants maintained sequences of letters or faces in working memory. Finally, other evidence indicates that hippocampal gamma activity aids episodic memory and involves distinctly different sub-gamma frequency bands corresponding to encoding and retrieval phases.

[0032] Theta oscillations (4–8 Hz) are linked to working and episodic memory processes. Intracranial EEG (iEEG) recordings demonstrate that during working memory, theta oscillations gate on and off (i.e., increase and sustain amplitude, then sharply decrease amplitude) across the encoding, maintenance, and retrieval phases. Other studies have observed increased scalp recording theta activity during working / memory maintenance. Several studies have concluded that scalp recording theta activity emerging from frontal / midline electrodes was the most robust neural correlation for verbal working / memory maintenance. Frontal / midline theta activity also tracks working / memory load, i.e., increased and sustained power, as a function of the number of items maintained within working memory.

[0033] Several studies have found that auditory / visual stimulation at gamma frequencies may improve dementia or Alzheimer's disease (AD)-related biomarkers and pathophysiology, and may provide neuroprotection when administered during the early stages of disease progression. The systems and methods described herein may induce or provide frequency responses or oscillatory neural activity at various target frequencies, as will be described in more detail below. Such responses or oscillatory neural activity may provide treatment for or otherwise improve the effects of various cognitive disorders (or any other cognitive disorders), such as any one of those described herein.

[0034] Referring to Figure 1, the diagram shows a block diagram of a system 100 for anti-phased binocular stimulation, according to an exemplary implementation of the present disclosure. The system 100 may include a control system 102 that is communicatively coupled to a plurality of light sources 104 (e.g., a first light source 104(1) and a second light source 104(2)) and an auditory output device 106. The control system 102 may include a vibration selection module (OSM) 108 and a brain rhythm stimulator (BRS) 110. As will be described in more detail below, the control system 102 may be configured to determine to output a visual stimulus at a target frequency. The control system 102 may be configured to output a first visual stimulus at a first frequency and phase to a first eye (e.g., via the first light source 104(1)) and a second visual stimulus at a second frequency and phase to a second eye (e.g., via the second light source 104(2)).

[0035] The control system 102 may include a vibration selection module (OSM) 108. The OSM 310 may be communicatively coupled to various other components or elements of the control system 102 (such as various input / output devices, user interface devices, user profiles, processing components, or other components / elements / devices / hardware, etc., as described in more detail below). The OSM 310 may be configured to determine, select, or otherwise identify various vibration states for stimulating a patient. The vibration states may be a target frequency and various sub-vibration states to provide or achieve stimulation at a target frequency, or may include a target frequency and various sub-vibration states to provide or achieve stimulation at a target frequency.

[0036] OSM108 may be configured to receive, detect, identify, or otherwise determine to output visual stimuli at a target frequency. The target frequency may be a frequency that is within a frequency band (such as a delta, theta, and / or gamma frequency range or band), or include frequencies that are within a frequency band. In some embodiments, OSM108 that defines, selects, or otherwise identifies the target frequency may be configured to receive user input (e.g., from the patient, a therapeutic professional associated with the patient, etc.). In some embodiments, OSM108 may be configured to identify the target frequency based on settings in a profile of the patient (e.g., a treatment plan that defines or sets a schedule for a certain target frequency at a certain time of day). In some embodiments, OSM108 may be configured to identify the target frequency based on or according to a simulated response to a given frequency (e.g., simulated brain responses to various input frequencies). For example, OSM108 may be configured to select a target frequency from input frequencies based on which of the input frequencies produces the strongest simulated brain response.

[0037] OSM108 may be configured to determine, detect, or otherwise identify vibration states for providing a target frequency. A vibration state may be defined as the frequency, amplitude, and phase of a visual stimulus that produces a corresponding frequency, or may include the frequency, amplitude, and phase of a visual stimulus that produces a corresponding frequency. In some embodiments, OSM108 may be configured to determine, select, or otherwise define vibration states for providing a stimulus response at a target frequency. The frequency of a vibration state may be less than the target frequency. OSM108 may be configured to define vibration states for stimuli provided to each of the patient's eyes. OSM108 may be configured to define a first vibration state for providing a visual stimulus to one of the patient's eyes, and a second vibration state for providing a visual stimulus to the other of the patient's eyes. OSM108 may be configured to define vibration states to specify individual frequencies, amplitudes, and phases for producing a stimulus response at a target frequency. In this regard, OSM108 may be configured to select, determine, or otherwise define different vibrational states for individual eyes in order to produce a stimulus response in the patient's brain based on the combined effect of different vibrational states.

[0038] Referring here to Figure 1 along with Figure 2, the OSM 108 may be configured to define or set vibrational states for providing a target frequency response. Specifically, Figure 2 depicts a first graph 200 showing a target frequency 202 and a second graph 204 showing vibrational states 206, 208 of stimulus waveforms providing a stimulus response at the target frequency. As shown, vibrational states 206, 208 may include one vibrational state for one stimulus waveform provided to one eye and another vibrational state for another stimulus waveform provided to the other eye. The target frequency illustrated in Figure 2 is 40 Hz, but it should be noted that the systems and methods described herein can be used over multiple frequencies in various frequency bands. For example, the target frequency may be 40 Hz, 30–40 Hz (35–40 Hz, or 38 Hz, etc.), 13–30 Hz, 8–13 Hz, 4–8 Hz, 0.5–4 Hz, or above 40 Hz, as illustrated.

[0039] As illustrated in Figure 2, the OSM 108 may be configured to determine a vibration state for a first visual stimulus and a vibration state for a second visual stimulus different from the first visual stimulus, based on or in accordance with an intended or target stimulus. The OSM 108 may be configured to determine the vibration state by selecting frequency, amplitude, and phase (e.g., for each vibration state) according to a target frequency. The OSM 108 may be configured to determine the phase of the vibration states such that they are out of phase with respect to each other (i.e., anti-phased). The OSM 108 may be configured to determine the phase such that the vibration state for the first visual stimulus is anti-phased / alternating / opposing with respect to the vibration state for the second visual stimulus. As illustrated in Figure 2, the vibration state 206 for the first visual stimulus and the vibration state 208 for the second visual stimulus may have the same frequency, but the corresponding signals may be anti-phased / alternating / opposing with respect to each other, thereby producing a constructive combined effect.

[0040] In some embodiments, the OSM108 may be configured to determine the frequency and amplitude for each vibration state based on or according to a target frequency. The OSM108 may be configured to determine the frequency and amplitude such that, when combined, the stimulus response is at a target frequency. Therefore, the frequency for each vibration state may be less than the target frequency. The frequency for each vibration state may be half of the target frequency. For example, the OSM108 may be configured to determine the frequency for one vibration state as equal to half of the target frequency, and the frequency for the other vibration state as equal to half of the target frequency. For example, if the target frequency is 35-40 Hz, the OSM108 may be configured to determine the frequency for each vibration state to be equal to 17.5-20 Hz.

[0041] The control system 102 may include a brain rhythm stimulator (BRS) 110. The BRS 110 may be configured to generate, produce, or otherwise provide control signals for output devices (e.g., a light source 104 and / or an auditory output device 106) to provide auditory and / or visual stimuli based on the vibration state determined by the OSM 108. The BRS 110 may be configured to use vibration states to produce or provide visual stimuli within a selected frequency (or frequency range) or within a frequency (or frequency range) via one or more output devices (e.g., a light source 104, an auditory output device 106, etc.). In some embodiments, the BRS 110 may output rhythmic visual stimuli to the user. The BRS 110 may include a pattern buffer, a generation module, a modulation module, and a filtering component, which may be operably connected to output devices to output stimuli to the patient.

[0042] In some embodiments, the OSM108 and BRS110 may be configured to determine, identify, or otherwise provide auditory signals for synchronization with visual stimuli. For example, the control system 102 may be configured to preprocess auditory stimuli, auditory inputs, or auditory signals to provide multi-channel rhythmic inputs (e.g., the beginning of a note). In some embodiments, auditory inputs or auditory signals are provided by the control system 102, by or via a built-in auditory playback system having access to a library of songs and / or other musical pieces. In some embodiments, the system 102 may further include a user-accessible graphical display and inputs / outputs to allow a user (e.g., a patient or therapist) to make selections from the library for playback. In other embodiments, in addition to, or as an alternative to, the built-in auditory playback system, the control system 102 may include an auxiliary auditory input to allow the system to receive input from a secondary playback system such as a personal music playback device (e.g., iPod®, MP3 player, smartphone, or equivalent). In some embodiments, in addition to or as an alternative to the auditory input described above, system 102 may include a microphone or similar device to enable system 102 to receive auditory input from ambient sounds, such as live music performances or music broadcasts from secondary speakers, such as the user's home stereo system. In embodiments in which auditory signals are received by the system through an auxiliary input via a built-in playback system or an MP3 player, the system may further include headphones or integrated speakers to enable a listener to hear the auditory signals 102 in real time.

[0043] The OSM108 may be configured to select the most prominent vibrations from an auditory signal in order to construct, select, or otherwise determine vibrational states for a synchronized visual stimulus to an auditory stimulus. In some embodiments, the OSM108 may couple a visual frequency stimulus to the pulsation and rhythmic structure of music. The OSM108 may select variable music-based frequencies in the delta, theta, and gamma ranges for a visual stimulus to the user synchronized to the auditory stimulus described herein. In some embodiments, the OSM108 may modulate a visual signal at a certain frequency to produce a visual stimulus synchronized to an auditory signal. For example, the OSM108 may amplitude modulate a beta or gamma frequency visual signal at a theta frequency (and / or at various other frequencies such as a delta frequency) derived or determined from a musical rhythm. The BRS110 may be configured to generate, produce, or otherwise provide control signals for output devices (e.g., light source 104 and / or auditory output device 106 in Figure 1) to provide auditory and / or visual stimuli based on data from the OSM108. In some embodiments, the BRS110 may be configured to use simulated neural vibrations to synchronize visual stimuli and musical rhythms within a selected frequency range via an output device (e.g., an auditory output device 106). In some embodiments, the BRS110 may also interface with a profile manager that stores data about one or more users or patients. Thus, in some embodiments, the information stored by the profile manager may also include previously captured or user-selected preferences for stimulus patterns, waveforms, or other parameters (such as color) preferred by the user / patient.

[0044] Referring here to Figures 3-5, what is depicted are embodiments of output devices for providing visual stimuli according to exemplary implementations of the present disclosure. Specifically, according to exemplary implementations of the present disclosure, Figure 3 depicts an embodiment of a head-wearable device 300 for providing visual stimuli, Figure 4 depicts an embodiment of a system 400 for providing visual stimuli, and Figure 5 depicts the illumination system 402 of the system 400 in Figure 4. The output device may be communicatively coupled to a control system 102 as described above. In some embodiments, the control system 102 may be embodied on the output device or incorporated into the output device. For example, the control system 102 may reside on the head-wearable device 300 and communicate with light sources 104(1), 104(2) and / or an auditory output device 106 to deliver auditory / visual stimuli locally to the patient. In some embodiments, the control system 102 may be remotely located and communicatively coupled to the output device (e.g., wirelessly). For example, the control system 102 may reside on a cloud-based server, computing device (e.g., remote or local device), and deliver wireless signals to the light source 104 and / or the auditory output device 106.

[0045] Specifically, referring to Figure 3, the output device used to provide auditory / visual stimuli may include a head-wearable device. The head-wearable device may include augmented reality glasses, virtual reality goggles, etc. The display of the head-wearable device may render visual patterns to the user. For example, if the head-wearable device includes augmented reality glasses, the augmented reality glasses may use visual patterns to augment the user's environment that is visible through the glasses. In another embodiment, if the head-wearable device includes virtual reality goggles (or other non-AR goggles), the goggles may display visual patterns on displays adjacent to both of the patient's eyes. In some embodiments, the display of the head-wearable device may provide visual stimuli to the patient by displaying separate visual patterns at different angles over each of the patient's eyes.

[0046] The head-wearable device 300 may include light sources 104(1) and 104(2) to deliver light to each of the patient's individual eyes. The light sources 104 may be light sources corresponding to various displays (or display devices) of the head-wearable device 300. For example, a display device may include multiple light sources, at least some of which are used to deliver light to each of the patient's individual eyes. The head-wearable device 300 may include a light source 104 for each eye. For example, one light source 104(1) may be dedicated to a particular eye (for example, the first light source 104(1) may be dedicated to the patient's right eye, and the second light source 104(2) may be dedicated to the patient's left eye). The light source 104 is arranged on or along the portion of the head wearable device 300 facing the interior, and (when the head wearable device 300 is worn by the patient) may deliver, direct, or otherwise output light toward and / or to the patient's eyes. In some embodiments, the light source 104 may include light-emitting diodes (LEDs) or other types or forms of lights. The light source 104 may be configured to output light at various colors / luminances / rhythmic frequencies, etc., or may be capable of outputting light at various colors / luminances / rhythmic frequencies, etc.

[0047] The head-wearable device 300 may include one or more auditory output devices 106. In some embodiments, the head-wearable device 300 may include a single auditory output device 106 arranged to produce or output auditory signals perceptible to both ears. For example, the auditory output device 106 may include a speaker or speaker system. In some embodiments, the head-wearable device 300 may include a plurality of auditory output devices 106 arranged at various locations on the head-wearable device 300. For example, the head-wearable device 300 may include plug-in earphones, local speakers, etc. (e.g., a left speaker or plug-in earphone for the left ear and a right speaker or plug-in earphone for the right ear) arranged to produce or output separate auditory signals perceptible to one of the patient's ears.

[0048] Referring specifically to Figures 4 and 5, the output device used to provide auditory / visual stimuli may include an auditory / visual system 400, including separate light systems 402(1), 402(2), as in the exemplary implementation of this disclosure. The lighting system 402 may include a visual stimulation ring 500, such as the one illustrated in Figure 5, which includes a plurality of LED lights 702 operably connected to the system 100. In some embodiments, as illustrated in Figure 4, the system 400 may include a dedicated lighting system 400 (or visual stimulation ring 500) for each patient eye. For example, the lighting systems 402(1), 402(2) may be positioned in front of the participant or patient (e.g., on their individual sides). The patient may focus on the center of the individual lighting system 402 (indicated by the cross 501 in Figure 5). To receive an anti-phased stimulus, the patient may be asked to focus between the centers of the individual lighting systems (e.g., illustrated as the midline 404 in Figure 4). In some embodiments, the illumination system 402 may be positioned at an appropriate distance to stimulate the retina at specific visual angles. For example, the illumination system 402 may be positioned at an appropriate distance to stimulate the retina at visual angles of 0–15 degrees, or 10–60 degrees, or 15–50 degrees, or 15–25 degrees, or 18–22 degrees, or 19–21 degrees. In some embodiments, the illumination system 402 may be positioned at an appropriate distance to stimulate the retina at a visual angle of 20 degrees where the rods of maximum density are found within the retina.

[0049] Although illustrated as a stimulating ring 500, various other output devices may also be used as part of the system 100, either together with the stimulating ring 500 or to complement the stimulating ring 700. For example, in some embodiments, the visual system 402 may include separate displays, a single wide display having dedicated sections for the patient's left and right eyes, and so on.

[0050] Referring now to Figures 6 and 7, what is depicted is a series of images illustrating the (actual) measured stimulus response to different visual stimulus inputs in one patient, and another series of images illustrating the average stimulus response across multiple patients with different visual stimulus inputs, respectively. In the leftmost column, what is depicted are the stimulus responses measured at 20 Hz and 40 Hz, respectively, based on a 40 Hz input visual stimulus over both eyes. As shown, at 20 Hz, measured across the patient's brain (dB, e.g., 10log 10 (μV 2 The response gain (in units) was nearly zero. At 40 Hz, the stimulus response, measured across the patient's brain, was strong in many parts of the patient's brain [e.g., the frontal and posterior parts].

[0051] In the center column, the measured stimulus responses at 20 Hz and 40 Hz are described, based on binocular isolation input visual stimuli that were out-of-phase (or out-of-phase or alternating) at 20 Hz. As illustrated in the center column, the alternating binocular isolation input stimuli produced a stronger response at 40 Hz across the brain compared to the stimulus response to the 40 Hz input stimuli. In addition, as shown in the right column, applying the 20 Hz stimulus to one eye (e.g., the stimulus response to 20 Hz applied to the right eye is depicted) produced a weak stimulus response at the 40 Hz harmonic, due to the nonlinear response of neurons and networks in the brain. However, the 40 Hz (intermediate) response to the alternating stimuli was much stronger than the simple harmonic response to the 20 Hz monocular stimulus (indicating a constructive interaction between the alternating binocular stimuli), while the 20 Hz (intermediate) response to the alternating stimuli was weaker than the response to the 20 Hz monocular stimulus (indicating interference between the alternating binocular stimuli at 20 Hz). These results were achieved both on an individual basis (as shown in Figure 6) and across a collective number of patients (as shown in Figure 7). Thus, it has been observed that the 20 Hz alternating stimuli elicit a stronger stimulus response compared to the 40 Hz stimulus.

[0052] Referring here to Figures 8A–8F, what is depicted is a series of graphs illustrating the power spectral density and gain for different types of input stimuli shown and described above with reference to Figures 6 and 7. The graphs show the logarithmic power (in dB, e.g., 10log10(μV2) units) and gain (relative to local mean values) averaged across the subject, where the strongest response to visual stimuli is expected to occur with respect to the electrode behind the Cz electrode. Specifically, Figures 8A–8C illustrate graphs of the power spectral density of stimulus responses to input stimuli at 40 Hz (binocular), 20 Hz alternating arrangement (binocular separation), and 20 Hz for one eye, respectively. Figures 8D–8F illustrate graphs of the gain of stimulus responses to the same individual input stimuli as shown in Figures 8A–8C. As shown in Figures 8B and 8E, the alternating 20Hz configuration produces the strongest stimulus response at 40Hz (measured by both logarithmic power and gain) compared to other input stimuli, but a weaker response at 20Hz compared to monocular stimulation. In addition, compared to a 40Hz stimulus applied to both eyes, the alternating 20Hz configuration (binocular-separated stimulus) has approximately 4dB higher power (as shown in Figure 8B compared to Figure 8A) and approximately 2.5dB higher gain (as shown in Figure 8F compared to Figure 8E) than the 40Hz stimulus. Thus, it is shown that the alternating stimuli produce a stronger stimulus response at the target frequency than by supplying visual stimulation at the target frequency itself.

[0053] Referring here to Figure 9, the flowchart depicts an exemplary method 900 providing anti-phased binocular or binocular separation stimuli, according to an exemplary implementation of the present disclosure. Method 900 may be carried out and / or implemented by components, elements, and / or hardware described herein, such as those described above with reference to Figures 1-8F. In brief, in 902, the device may determine a target frequency. In 904, the device may determine frequency and phase. In 906, the device may decide to output a visual stimulus. In 908, the device may output first and second visual stimuli.

[0054] In 902, the device may determine the target frequency. The device may be, for example, a control system 102 (in Figure 1) including an OSM 108, or may include a control system 102. The device may determine the target frequency based on, or according to, various received, detected, and / or identified inputs. For example, the device may determine the target frequency in response to receiving user input (e.g., from the patient, from a therapist, etc.) via an input / output device. In another embodiment, the device may determine the target frequency in response to identifying the target frequency in the treatment schedule of a patient profile (e.g., maintained by a profile manager 1306). In yet another embodiment, the device may determine the target frequency based on feedback from a simulation (e.g., via a synchronization simulator 1308). The target frequency may be the frequency at which the patient's brain stimulation will be received. Thus, the target frequency may be the frequency of the stimulus response rather than the frequency of the visual stimulus.

[0055] In 904, the device may determine frequency and phase. In some embodiments, the device may determine, derive, calculate, or otherwise identify frequency and phase for a visual stimulus in order to achieve, produce, request, or otherwise provide a frequency response at a target frequency. In some embodiments, the device may determine a vibration state for each patient eye, the vibration state including frequency and phase of vibration for a visual stimulus. Both vibration states for each eye may provide a frequency response at a target frequency. In other words, both vibration states for a first eye (e.g., left eye) (e.g., including a first frequency and a first phase) and vibration states for a second eye (e.g., right eye) (e.g., including a second frequency and a second phase) may provide a frequency response in the patient's brain at a target frequency.

[0056] In some embodiments, the device may determine the vibration state based on or according to a target frequency. For example, the device may determine the frequency for a vibration state as a function of the target frequency. In some embodiments, the sum of the first and second frequencies (e.g., for individual vibration states) may be equal to the target frequency. For example, the first frequency may be equal to half the target frequency, and the second frequency may be equal to half the target frequency. In addition, the phases for individual vibration states may be out-of-phase with respect to each other (e.g., the vibration states may have different phases). In other words, the first and second phases (e.g., for individual vibration states) may be opposite to each other.

[0057] In one embodiment, the target frequency determined in 902 may be equal to 35-40 Hz. For example, the target frequency may be determined to be 38 Hz. The device may determine the first and second frequencies and the first and second phases according to the target frequency. For example, the device may determine the first phase so that the resulting visual stimulus is opposed / out-phased / de-phased with respect to the second phase so that it produces a constructive effect. The device may determine the first and second frequencies to be equal to half of the target frequency so that the resulting visual stimulus (when combined) produces a stimulus response at the target frequency. Following the above embodiment, the device may determine the first and second frequencies to be equal to each other and be in the range of 17.5-20 Hz (e.g., 19 Hz).

[0058] In 906, the device may decide to output a visual stimulus. In some embodiments, the device may decide to output a visual stimulus to produce a stimulus response at a target frequency. The device may decide to output a visual stimulus in response to determining the frequency and phase that together produce a stimulus response at a target frequency. The device may decide to output a visual stimulus according to a schedule (e.g., a therapy schedule for a session). The device may decide to output a visual stimulus in response to receiving a signal (e.g., from an input device) to initiate the patient's visual stimulus.

[0059] In 908, the device may output first and second visual stimuli. In some embodiments, the device may output a first visual stimulus to the first eye at a first frequency and phase, and a second visual stimulus to the second eye at a second frequency and phase. The first visual stimulus may include or correspond to a first vibrational state, and the second visual stimulus may include or correspond to a second vibrational state. In other words, the first visual stimulus may have a first frequency and phase, and the second visual stimulus may have a second frequency and phase, both of which are described above with reference to 904. Both the first and second visual stimuli may provide a stimulus response at a target frequency. In other words, the first and second frequencies may not be identical to the target frequency. However, since the first and second visual stimuli are constructive (due to the first and second phases being out-of-phase with respect to each other or being arranged alternately), both the first and second visual stimuli may provide a stimulus response at the target frequency.

[0060] In some embodiments, the device may output first and second visual stimuli by controlling one or more light sources (e.g., light sources 104) to output light at first and second frequencies and first and second phases. For example, the device may communicate signals to the light sources 104 (e.g., via either a wired or wireless connection) to output visual stimuli. The device may communicate a first signal to a first set of light sources 104 (e.g., first light source 104(1)) to output a first visual stimulus to one eye of the patient, and a second signal to a second set of light sources 104 (e.g., second light source 104(2)) to output a second visual stimulus to the other eye of the patient.

[0061] In some embodiments, a device implementing 902-908 may include a light that outputs a visual stimulus. For example, the device may include a light source 104 as described above with reference to Figure 1. For example, the device may include a head-wearable device 300 and / or system 400. In some embodiments, a device implementing 902-908 may not include a light. For example, the device may be communicatively coupled to the light source 104 and output first and second visual stimuli by transmitting / communicating / transmitting signals that cause the light source 104 to output a visual stimulus.

[0062] In some embodiments, the device may output an auditory signal while outputting first and second visual stimuli. The auditory signal may be synchronized with the first and second visual stimuli as described above. In some embodiments, the auditory signal may be music or correspond to music. The device may output an auditory signal by transmitting the auditory signal to an auditory output device to output music. The device may modify the auditory signal and / or coordinate the first and second visual stimuli so that the first and second visual stimuli are synchronized with music corresponding to the auditory signal.

[0063] Figure 10 depicts an exemplary block diagram of an exemplary computer system 1000. Various components, elements, and / or hardware described herein (such as those described with reference to Figure 1) may be implemented by, through, and / or on the computer system 1000 containing the components. The computer system or computing device 1000 may include a data processing system or its components, or may be used to implement a data processing system or its components. The computing system 1000 includes at least one bus 1005 or other communication component for communicating information, and at least one processor 1010 or processing circuit coupled to the bus 1005 for processing information. The computing system 1000 may also include one or more processors 1010 or processing circuits coupled to the bus for processing information. The computing system 1000 also includes at least one main memory 1015, such as random access memory (RAM) or other dynamic storage device, coupled to the bus 1005 for storing information and instructions to be executed by the processor 1010. Main memory 1015 can be used to store information while the processor 1010 is executing instructions. The computing system 1000 may further include at least one read-only memory (ROM) 1020 or other static storage device coupled to the bus 1005 for storing static information and instructions for the processor 1010. A storage device 1025, such as a solid-state device, magnetic disk, or optical disk, may be coupled to the bus 1005 to persistently store information and instructions.

[0064] The computing system 1000 may be coupled to a display 1035, such as a liquid crystal display or an active-matrix display, via a bus 1005 to display information to the user. An input device 1030, such as a keyboard or voice interface, may be coupled to the bus 1005 to communicate information and commands to the processor 1010. The input device 1030 may include a touchscreen display 1035. The input device 1030 may also include a cursor control device, such as a mouse, trackball, or cursor directional keys, for communicating directional information and command selections to the processor 1010 and for controlling cursor movement on the display 1035.

[0065] The processes, systems, and methods described herein can be implemented by a computing system 1000 in which a processor 1010 executes a sequence of instructions contained in main memory 1015. Such instructions can be read into main memory 1015 from another computer-readable medium, such as a storage device 1025. The execution of the sequence of instructions contained in main memory 1015 causes the computing system 1000 to perform the illustrative processes described herein. One or more processors in a multiprocessing sequence may also be employed to execute instructions contained in main memory 1015. Wired networks can be used in place of or in combination with software instructions, along with the systems and methods described herein. The systems and methods described herein are not limited to any specific combination of hardware networks and software.

[0066] An exemplary computing system is illustrated in Figure 10, but the subject matter, including the operations described herein, can be implemented in other types of digital electronic networks, or in computer software, firmware, or hardware, or a combination of one or more of these, including the structures disclosed herein and their structural equivalents.

[0067] While several illustrative implementations have been described here, it is clear that those described are illustrative, not limiting, and are presented as examples. In particular, many of the examples presented herein involve specific combinations of method actions or system elements, but these actions and elements can also be combined in other ways to accomplish the same objective. Actions, elements, and features discussed in relation to one implementation are not intended to be excluded from similar roles in other or multiple implementations.

[0068] Hardware and data processing components used to implement the various processes, operations, illustrative logic, logic blocks, modules, and circuits described in connection with the embodiments disclosed herein may be implemented or carried out using a general-purpose single-chip processor or general-purpose multi-chip processor, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof, designed to perform the functions described herein. The general-purpose processor may be a microprocessor, or any conventional processor, controller, microcontroller, or state machine. The processor may also be implemented as a combination of computing devices such as a combination of a DSP and a microprocessor, multiple microprocessors, one or more microprocessors combined with a DSP core, or any other such configuration. In some embodiments, specific processes and methods may be carried out by a network of circuits specific to a given function. Memory (e.g., memory, memory unit, storage device, etc.) may include one or more devices (e.g., RAM, ROM, flash memory, hard disk storage device, etc.) for storing data and / or computer code to complete or facilitate the various processes, layers, and modules described herein. Memory may be volatile memory or non-volatile memory, or may include volatile memory or non-volatile memory, and may include database components, object code components, script components, or any other type of information structure to support the various activities and information structures described herein. In an exemplary embodiment, memory is communicably connected to a processor via processing circuitry and includes computer code for executing one or more processes described herein (e.g., by processing circuitry and / or processor).

[0069] This disclosure envisions methods, systems, and program products on any machine-readable medium for performing various operations. Embodiments of this disclosure may be implemented using existing computer processors, or by specialized computer processors for appropriate systems incorporated for this purpose or other purposes, or by wired systems. Embodiments within the scope of this disclosure include program products, which comprise a machine-readable medium for holding or having machine-executable instructions or data structures stored thereon. Such machine-readable medium may be any available medium accessible by a general-purpose or specialized computer or other machine with a processor. By example, such machine-readable medium may include RAM, ROM, EPROM, EEPROM, or other optical disk storage devices, magnetic disk storage devices, or other magnetic storage devices, or any other medium, which may be used to hold or store desired program code in the form of machine-executable instructions or data structures and accessible by a general-purpose or specialized computer or other machine with a processor. The above combinations also fall within the scope of machine-readable medium. Machine-executable instructions include, for example, instructions and data that cause a general-purpose computer, specialized computer, or specialized processing machine to perform a certain function or group of functions.

[0070] The terminology and grammar used herein are for illustrative purposes only and should not be considered limiting. The use herein of “including,” “comprising,” “having,” “containing,” “involving,” “characterized by,” “characterized in that,” and their variations, means that the following listed items, their equivalents, and additional items, as well as alternative implementations consisting only of the following listed items, are included. In a single implementation, the systems and methods described herein consist of any combination, or all, of one or more of the elements, actions, or components described.

[0071] Any singular reference in this specification to an implementation, element, or action of a system or method may also include implementations containing multiple such elements, and any plural reference in this specification to an implementation, element, or action may also include implementations containing only a single element. Singular or plural references are not intended to limit the disclosed systems or methods, their components, actions, or elements to one or more configurations. Any reference to an action or element based on any information, action, or element may include, at least partially, an implementation based on any information, action, or element.

[0072] Any implementation disclosed herein can be combined with any other implementation or embodiment, and references to “an implementation,” “some implementations,” “one implementation,” or equivalents are not necessarily mutually exclusive and are intended to indicate that certain features, structures, or characteristics described in relation to that implementation may be included in at least one implementation or embodiment. Such terms as used herein do not necessarily all refer to the same implementation. Any implementation can be combined with any other implementation, comprehensively or exclusively, in any manner consistent with the aspects and implementations disclosed herein.

[0073] Where reference numerals follow drawings, detailed descriptions, or technical features within any claims, the reference numerals are included to enhance clarity of the drawings, detailed descriptions, and claims. Therefore, neither the reference numerals nor their absence shall have any limiting effect on the scope of any claim element.

[0074] The systems and methods described herein may be embodied in other specific forms without departing from their characteristics. Any reference to terms expressing degree includes a variation of + / - 10% from a given measurement, unit, or range unless expressly indicated otherwise. Combined elements may be electrically, mechanically, or physically coupled to one another, either directly or with intervening elements. The scope of the systems and methods described herein is therefore indicated not by the foregoing description but by the appended claims, and modifications that are equivalent in meaning and scope to the claims are included therein.

[0075] The term “coupled” and its variations include direct or indirect joining of two members to each other. Such joining may be permanent (e.g., permanent or fixed) or movable (e.g., removable or detachable). Such joining may be achieved using two members that are directly coupled to or to each other, two members that are coupled to each other using a separate intervening member and any additional intermediate member that is coupled to each other, or two members that are coupled to each other using an intervening member that is integrally formed with one of the two members as a single, integrated body. If “coupled” or its variations are modified by an additional term (e.g., “directly coupled”), the general definition of “coupled” provided above is modified by the plain language meaning of the additional term (e.g., “directly coupled” means joining of two members without any separate intervening member), resulting in a narrower definition than the general definition of “coupled” provided above. Such connections may be mechanical, electrical, or fluid.

[0076] A reference using "or" can be interpreted as inclusive, such that any term described using "or" may refer to a single term, more than one, or all of the terms described. A reference to "at least one of 'A' and 'B'" may include "A" only, "B" only, or both "A" and "B". Such references, when used with "comprising" or other non-restrictive technical terms, may include additional items.

[0077] Modifications to the described elements and their functions, such as variations in size, dimensions, structure, shape, and proportions of various elements, parameter values, mounting arrangements, material use, color, and orientation, can occur without substantially departing from the teachings and merits of the subject matter disclosed herein. For example, elements shown as being formed as a single unit can be constructed from multiple parts or elements, the positions of elements can be reversed or otherwise varied, and the properties or number of discrete elements or positions can be altered or varied. Other substitutions, modifications, changes, and omissions can also be made in the design, operating conditions, and arrangements of the disclosed elements and functions without departing from the scope of this disclosure.

Claims

1. It is a method, The device determines the target frequency of the stimulus response, The device outputs a first visual stimulus at a first frequency and a first phase to the first eye, The device outputs a second visual stimulus at a second frequency and a second phase to the second eye, wherein both the first visual stimulus and the second visual stimulus produce the stimulus response at the target frequency. Methods that include...

2. The method according to claim 1, wherein the first frequency is half of the target frequency, and the second frequency is half of the target frequency.

3. The method according to claim 1, wherein the second phase is in opposite phase to the first phase.

4. The method according to claim 1, wherein the target frequency is 35 to 40 Hz.

5. The method according to claim 4, wherein the sum of the first frequency and the second frequency is equal to the target frequency.

6. The method according to claim 4, wherein the target frequency is equal to 38 Hz, the first frequency is equal to 19 Hz, and the second frequency is equal to 19 Hz.

7. The device comprises one or more first light sources for stimulating the first eye and one or more second light sources for stimulating the second eye. Outputting the first visual stimulus includes controlling one or more first light sources to output light at the first frequency and the first phase, Outputting the second visual stimulus includes controlling one or more second light sources to output light at the second frequency and the second phase. The method according to claim 1.

8. The method according to claim 7, wherein the device comprises a head wearable device, the head wearable device comprises one or more first light sources located at a first position of the head wearable device, and one or more second light sources located at a second position of the head wearable device, the first position corresponding to stimulating the first eye when the head wearable device is worn, and the second position corresponding to stimulating the second eye when the head wearable device is worn.

9. Outputting the first visual stimulus and the second visual stimulus means The device outputs an auditory signal while outputting the first visual stimulus, The device outputs the auditory signal while outputting the second visual stimulus, and the auditory signal is synchronized with the first visual stimulus and the second visual stimulus. The method according to claim 1, including the method described in claim 1.

10. The method according to claim 1, wherein the target frequency is within a frequency band, and the frequency band is one of 30 Hz to 40 Hz, 13 Hz to 30 Hz, 8 Hz to 13 Hz, 4 Hz to 8 Hz, or 0.5 Hz to 4 Hz.

11. It is a device, One or more light sources, One or more processors, Determining the target frequency of the stimulus response, Outputting a first visual stimulus at a first frequency and a first phase to a first eye, Outputting a second visual stimulus at a second frequency and second phase to a second eye, wherein both the first and second visual stimuli produce the stimulus response at the target frequency. One or more processors configured to perform the following: A device equipped with the following features.

12. The device according to claim 11, wherein the first frequency is half of the target frequency, the second frequency is half of the target frequency, and the second phase is out-of-phase with respect to the first phase.

13. The device according to claim 11, wherein the target frequency is equal to 38 Hz, the first frequency is equal to 19 Hz, and the second frequency is equal to 19 Hz.

14. The device according to claim 11, wherein one or more processors are configured to output an auditory signal while outputting the first visual stimulus and the second visual stimulus.

15. The device according to claim 11, wherein the auditory signal is synchronized with the first visual stimulus and the second visual stimulus.

16. It is a system, One or more light sources, One or more processors, Determining the target frequency of the stimulus response, Outputting a first visual stimulus at a first frequency and a first phase to a first eye, Outputting a second visual stimulus at a second frequency and second phase to a second eye, wherein both the first and second visual stimuli produce the stimulus response at the target frequency. One or more processors configured to perform the following: A system that includes these features.

17. The system according to claim 16, wherein the one or more processors and the one or more processors are embodied on a head-mounted wearable device.

18. The system according to claim 16, wherein the first frequency is half of the target frequency, and the second frequency is half of the target frequency.

19. The system according to claim 16, wherein the second phase is in opposite phase to the first phase.

20. The system according to claim 16, wherein the target frequency is equal to 38 Hz, the first frequency is equal to 19 Hz, and the second frequency is equal to 19 Hz.

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