WO2015028479A1

WO2015028479A1 - Stimulating system with vestibular-tactile and auditory stimulation

Info

Publication number: WO2015028479A1
Application number: PCT/EP2014/068109
Authority: WO
Inventors: Raymond Van Ee; Ronaldus Maria Aarts; Maria Estrella Mena Benito; Franciscus Jacobus Vossen
Original assignee: Koninklijke Philips N.V.
Priority date: 2013-08-28
Filing date: 2014-08-27
Publication date: 2015-03-05
Also published as: WO2015028480A1

Abstract

A stimulation system with a stimulator device, e.g. comprising an inflatable/deflatable pillow, arranged to engage with a person's head in order to generate rocking movements of the person's head in a manner stimulating the person's vestibular system, e.g. side-to-side rolls of the person's head. A control system controls the stimulator device in accordance with an auditory input to the person. Preferably, the control system serves to rhythmically synchronize the auditory input and the rocking head movements, e.g. to have the same repetition frequency of between 1/30 Hz and 2 Hz, e.g. 1/10 Hz. The combined synchronous audio and vestibular-tactile stimulation has been shown effective in reducing blood pressure,distracting tinnitus patients form their discomfort, and to help them to fall asleep. The auditory input may be a repeated sound signal provided by headphones to the person, e.g. a recording of breaking sea waves, singing birds etc., with a dominating audible feature having a perioditicy aligned with the head movements.

Description

Stimulating system with vestibular-tactile and auditory stimulation

FIELD OF THE INVENTION

The present invention relates to the field of stimulation of a user, e.g. for medical purposes, such as for limiting discomfort for a user suffering from tinnitus. BACKGROUND OF THE INVENTION

Tinnitus is the perception of meaningless sound, a tone or a noise, that is physically not present. Sufferers describe it as ringing in the ear. Most people have had the sensation of temporary tinnitus caused by rock-music concerts, fever, or stressful situations. Usually such temporary tinnitus goes away after one night's sleep.

Chronic (as opposed to temporary) tinnitus is experienced as a problem on a daily basis by about 10% of the worldwide adult population. Chronic tinnitus can be very distressing. It prevents 1% of the people from living a normal life, and it is accompanied by stress, sleep deprivation, and anxiety, for some leading to committing suicide. In the US alone, there are 50 million sufferers of whom 13 million patients seek medical help involving 1.4B$ yearly compensation via medical insurance. There were 744.159 war- veterans with a tinnitus disability award between 2004 and 2010 (source: American Tinnitus Association, May 2010). Thus, tinnitus is a serious problem, involving serious costs to society. The American Tinnitus Association estimates that costs in 2014 will involve 3.5B$ (per year in the US alone).

In spite of the high prevalence, successful therapies are presently not available.

Various treatments are being applied but generally tinnitus is at best reduced and this reduction is temporary. A number of proposed medications have turned out to be ineffective, others require further study. Psychological treatments (cognitive behavioral therapy, retraining therapy) or audio logical treatments (hearing aids, masking devices) are frequently being used. Some of these show beneficial results only in a limited number of patients. There are over 300 pharmaceutical pills available. They tend to have a temporary positive effect, but none of them has proven to be better than a placebo and none of them have FDA approval.

Drastic therapies involving cochlear implantation or brain surgery are currently being studied. Electrical stimulation via a cochlear implant in patients who already had profound hearing loss in the to be implanted ear, showed promising results, however, it would be a dramatic intervention in patients with fair to good hearing.

US 2009/0082831 Al describes an electrical system with an electrode assembly arranged to stimulate a person's vestibular system without any mechanical engaging means. The system is described to provide a pleasant effect that can help a person to fall asleep and reduce anxiety. However, the system is rather complex and requires e.g. safety precautions since it involves electrical stimulation of the person, and some persons find the pure electrical vestibular stimulation unnatural and unpleasant.

US 2011/0251535 Al describes an apparatus and method for introducing multisensory integration. The apparatus includes an ergonomically contoured seating device, at least one vibrating acoustic device, at least one plate for dispersing vibration throughout the entire seating device, a rotatable mechanism for rotating the seating device while a person in seated therein. The apparatus is designed for the purpose of therapy including various sensory inputs, such as vibration transducers coupled with audio signals. However, there is no indication that the disclosed apparatus could have any effect on tinnitus or similar conditions.

SUMMARY OF THE INVENTION

In view of the above, it would be advantageous to provide a system and a method for reducing the negative effects of tinnitus, e.g. sleep deprivation.

In a first aspect, the invention provides a stimulation system for providing a person with a stimulation, or more specifically a sensory stimulation, the system comprising

- a stimulator device arranged to engage with the person's head in order to generate rocking movements of the person's head in a manner stimulating the person's vestibular system, and

- a control system arranged to control the stimulator device in accordance with an auditory input to the person, so as to align at least one audible feature in the auditory input with the rocking movements of the person's head.

Such system with a combined auditory and vestibular stimulation by means of head rocking, has been verified to provide tinnitus sufferers with a pleasant sensation. Further, the combined stimulation distracts the person's attention away from the tinnitus, thereby helping the person to fall asleep. Surprisingly it has further been found that combined auditory and vestibular stimulation by means of head rocking may help in reducing a person's blood pressure. The system can be implemented with rather simple components, either as a dedicated system or by means of one or more dedicated part(s) to be operated by a standard component such as a mobile phone, a computer or the like as control device, or at least as part of the control device, with appropriate application software. Especially, both the control function and the generation of the auditory input could be provided by a smart phone wire or wirelessly controlling a dedicated stimulation device. The stimulation device may be designed to stimulate the person's head in a lying position, e.g. on a bed, or in a seated position, e.g. in a chair. The stimulation device, or part of it, may be built together with a bed or a chair. Alternatively, the stimulation device is formed as a pillow, or as an inflatable cushion to be mounted in, below or above a normal pillow.

The way of aligning auditory features of the auditory input with the rocking stimulation can be achieved in various ways, however it can be obtained in rather simple ways, preferably by providing an auditory input and a rocking stimulation which are rhythmically aligned, e.g. which have the same periodicity, and especially the auditory input and the rocking movements are controlled so they are rhythmically synchronized. As an example, the auditory input can be a repeated signal, e.g. a recording or synthesized sound of seawaves, with the same repetition frequency as a gentle side-to-side rocking stimulation of the person's head. Hereby, an auditory feature, amplitude periodicity, is aligned with the head rocking stimulation. As a further example, the auditory input could be provided by the user, e.g. playing his/her favourite rhythmic piece of music, while the control system is programmed to control the repetition frequency of the rocking movement of the person's head to match a detected rhythmic frequency of the music, or an integer fraction thereof.

The invention is based on the following insight. Traditionally, chronic tinnitus is thought to be the result of a functional reorganization of the auditory pathways following receptor (hair-cell signal processing) damage. Although it is known, anecdotally, for a long time that a major factor contributing to suffering from tinnitus is paying "attention" to the annoying sound, only very recently there is neuroscientific evidence that neuronal pathways involved in the processing of attention play a cardinal role. Attention to the tinnitus enhances annoyance of the tinnitus (just as happens with attention to a pinching shoe), i.e. it boosts the brain activity underlying the tinnitus. On the other hand, watching a good movie, or falling in love, reduces perceived tinnitus. In addition, staying busy with meaningful engaging activities helps to automatically distract attention away from tinnitus. Thus, although the fact that physical ear receptor damage underlies the origin of tinnitus, it is now believed that dysregulation of the interaction between limbic (emotional), and auditory networks in the brain underlie the chronic aspect of tinnitus. In this dysregulation, attention plays a cardinal role, resulting in disordered evaluation of the tinnitus' perceptual relevance, entailing disordered gain control of the tinnitus percept. The same limbic neural network has been implicated in evaluation of reward, emotion, and averseness for other perceptual stimuli as well. This suggests that this neuronal network is part of a general "appraisal network" determining which sensations are important, and ultimately affecting how (or whether) those sensations are experienced. It has been described that this neuronal pathway does indeed differ in the brains of individuals with tinnitus.

Thus, the invention capitalizes on the insight that control of attention is important for reducing tinnitus comfort. It controls the attentional state of the patient through the use of synchronous sensory signals, namely via the aligned feature(s) of the auditory input and the rocking vestibular stimulation. With the head rocking type of vestibular stimulation, the control of the attentional processes applies synchronous information to three perceptual modalities simultaneously: auditory, vestibular and tactile (mechanical, touch) signals. Via this attentional control, the patient is distracted away from the tinnitus, thereby reducing the discomfort for tinnitus sufferers.

It has further surprisingly been found that the head rocking type of vestibular stimulation which provides up and down movements or left to right side-to-side rolling head movements with a predefined frequency and with a predefined amplitude may help in lowering a person's blood pressure. It is hypothised that the rocking movements provide adjustments in the person's breathing and circulatory system (through baroreceptors in the body) and these adjustments cause a reduction in the blood pressure. It has further been found that the effect of the vestibular stimuli on the reduction of blood pressure may be enhanced by adding auditory stimulation to vestibular stimulation.

A prototype system has been designed to test the effect of rhythmically synchronous auditory, and vestibular (and tactile) stimulation on a number of tinnitus patients and on the blood pressure of a number of persons. The results, data will be presented below, show quantitatively demonstrated that the system according to the invention helps to relief tinnitus patients from their tinnitus distress and helps to reduce blood pressure, also for persons that do not suffer from tinnitus.

The alignment of link between auditory feature(s) and the rocking stimulation can be provided in several ways. Especially, the alignment may be achieved by at least one audible feature in the auditory input being rhythmically aligned with the rocking movements of the person's head. More specifically, a sound signal can be provided which is rhythmically synchronous with the head rocking stimulation, especially the sound signal may have the same static periodicity (or the same amplitude envelope frequency) as the head rocking stimulation. This can be obtained by a simple repetition of an audio signal, or playing an audio signal with a dominating audible feature, e.g. variable amplitude, having a static frequency. Alternatively, the frequency of the rocking stimulation and the audible feature are different, but linked by an integer times or an integer fraction of each other, thereby still ensuring a perceived rhythmic synchronicity of the auditory input and the vestibular stimulation.

The stimulator device is preferably controlled so as to generate rocking movements of the person's head with an amplitude sufficiently strong to stimulate the person's vestibular system, but preferably the amplitude is matched to provide an amplitude weak enough to avoid any harmful or unpleasant effects. The stimulation direction and the way of engaging with the person's head can be implemented in various ways. Preferably, the stimulation pattern provides a harmonic movement of the person's head without any abrupt changes. The stimulation direction may be variable, e.g. selectable by the user. Stimulation directions may be designed so as to provide such as:

1) side-to-side rolling head movements, i.e. stimulation primarily in a direction in a horizontal, when the person is lying;

2) up-and-down or nodding head movements, i.e. stimulation primarily in a direction in a vertical plane, when the person is lying; or

3) a combination of 1) and 2).

Thus, in some embodiments, the stimulation device is arranged to provide rocking movements of the person's head in a horizontal plane; in some embodiments, the stimulation device is arranged to provide rocking movements of the person's head in a vertical plane, while in some embodiments, the stimulation device is arranged to provide rocking movements of the person's head as a combined stimulation in a vertical and a horizontal plane.

In some embodiments, the control system is arranged to control the stimulator device so as to provide periodic rocking movements of the person's head with a repetition frequency of between 1/30 Hz and 2 Hz, or more specifically between 1/20 Hz and 1/2 Hz. E.g. a repetition frequency of around 1/10 Hz has proven to provide a good effect, e.g. with an auditory input in the form of a recording of seaways breaking, i.e. a sound with a slow increase and decrease in amplitude with the same repetition frequency.

The control system may be arranged to initiate a stimulation session by a fade- in phase in which a rocking movement of the person's head is different from later in the stimulation session. Especially, the amplitude of the rocking movement may be slowly increased during the fade-in phase, starting from zero or a very low value. Alternatively, or additionally, the stimulation frequency may be slowly increased during the fade-in phase. Such fade-in phase serves to provide the person with a pleasant sensation allowing the person to slowly focus his/her attention towards the combined stimulation.

The system may comprise a sensor connected to the control system, wherein the sensor is arranged to detect a parameter indicative of the person sleeping. Hereby, the system can adapt the vestibular stimulation, optionally also the auditory input, accordingly. Especially, it may be preferred to stop or fade-out the stimulation after it has been detected that the person has fallen asleep. The sensor may comprise an accelerometer mounted so as to detect movements of the person.

The system may further comprise a further sensor connected to the control system, wherein the further sensor is arranged to measure the person's blood pressure, heart rate, heart rate variability or respiration rate. The system is configured to adapt the vestibular stimulation, optionally also the auditory input, in response to the measured blood pressure, heart rate, heart rate variability or respiration rate. In a preferred embodiment the combined rocking rate and the sound amplitude variation rate create a paced breathing experience by providing the person a rocking and sound amplitude variation at a predetermined rate or pace. In a further embodiment the pace is based on the average natural breathing rate or is adjusted to a percentage of the person's (instanteneous) measured breathing rate. This percentage is in the range of 80% to 95% and preferably 90%. The natural breathing rate is the breathing rate of a person at rest, and may for example be determined when the person has been in a lying position for 10 minutes with no stimulation (auditory, vestibular or otherwise) provided.

The stimulation device may comprise a mechanical actuator attached to the person's head and arranged to engage with both sides of the person's head, so as to allow side-to-side rocking head movements. Alternatively, the stimulator device may comprise a pillow arranged for the person's head to rest thereon, wherein the pillow comprises at least one compartment capable of being inflated and deflated, so as to cause the rocking

movements of the person's head, upon successive inflations and deflations of the at least one compartment. Especially, the system may comprise a pump system connected to the control system, and connected to inflate and deflate the at least one compartment, wherein the pump system comprises a plurality of micropumps built into the pillow.

The system may comprise a sound system arranged to provide the auditory input to the person. Especially, the control system is arranged to control the sound system. Alternatively, or additionally, the auditory input can be provided by a device not being part of the system, e.g. provided by an external sound source.

The control system may be arranged to adjust at least one of: a frequency of an audible feature in the auditory input, and a repetition frequency of the rocking movements of the person's head. In some embodiments, the control system is capable of adjusting both of a frequency of an audible feature in the auditory input, and a repetition frequency of the rocking movements of the person's head. By adjusting the repetition frequency of the stimulator device, the system may be used together with an auditory input provided from outside and still be able to obtain a rhythmical alignment of the auditory input and the rocking movements of the person's head. In embodiments where the system can control the auditory input, e.g. by generating an audio signal to be presented to the person, it may be advantageous that a frequency of an audible feature, e.g. repetition frequency, can be adjusted by the system.

The control system may be arranged to adjust a frequency of the rocking movements of the person's head in response to a frequency of an audible feature in the auditory input. Especially, the control system may be connected to receive the auditory input, or a digital representation thereof, e.g. to be able to detect a dominating rhythmic frequency therein, in case the auditory input is provided by an external source.

The auditory input may comprise a repetitive audio sequence with a repetition frequency being an integer times, or an integer fraction of, a repetition frequency of the rocking movements of the person's head. This way, rhythmical alignment is present.

Especially, the rocking frequency and the repetition frequency may be the same, however if related by an integer factor or fraction, an good pleasant sensation and relaxing effect is achieved. The auditory intput may be generated based on natural recorded sounds and/or synthesized sounds.

There are a plurality of applications of the invention related to the well-being and health of both tinnitus sufferers and also for the general public with problems relaxing and/or falling asleep. The invention helps to unwind the mind and to shorten sleep-onset latency. It can therefore be applied, next to tinnitus, also for other attention-related sleep- onset problems. For example sleep-onset problems caused by: Insomnia in general; Chronic pain; Stressful mind; Anxiety; ADHD; Depression. The invention is also applicable within health care via subscription of medical doctors in hospitals for the treatment of tinnitus. Patients can use the audio -vestibular stimulation system during therapy sessions with the help of a therapeutic doctor. Likewise, the system can be used for the treatment of pain in general. Further test results indicate that the invention may help in reducing a person's blood pressure.

An advantage is that the system can be implemented with simple means, and therefore it is suited to be used for home care solutions, thus matching changes in society. Further, the invention is applicable within ambient healing environments (e.g. MR og PET scanners in hospitals) to distract a patient's attention from anxiety or stress during medical examination. Still further, the invention is applicable within consumer life style to help people relax and to fall asleep, or merely to provide a person with a pleasant feeling, but potentially also to reduc the need for drugs to help relax and to fall asleep.

In a second aspect, the invention provides a method for stimulating a person, the method comprising

rocking the person's head so as to provide movements of the person's head in a manner stimulating the person's vestibular system, and

controlling said rocking of the person's head in accordance with an auditory input to the person, so as to align at least one audible feature in the auditory input with the rocking movements of the person's head.

In a third aspect, the invention provides a method for reducing discomfort of a person suffering from tinnitus, the method comprising

In a fourth aspect, the invention provides a method for reducing a blood pressure of a person, the method comprising

It is to be understood, that the methods of the second and third aspects can be performed automatically or semi-automatically, when implemented as a computer executable program code and executed on a computer or processor controlled control system. It is appreciated that the same advantages and embodiments of the first aspect apply as well for the second and third aspects. In general the first, second and third aspects may be combined and coupled in any way possible within the scope of the invention. These and other aspects, features and/or advantages of the invention will be apparent from and elucidated with reference to the embodiments described hereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention will be described, by way of example only, with reference to the drawings, in which

Figure 1 illustrates basic elements of a system embodiment,

Figures 2a and 2b illustrate graphs showing temporal amplitude variations for auditory input and head rocking movement which are rhythmically synchronized with a frequency of 1/10 Hz, and with an initial fade-in phase another embodiment,

Figure 3 illustrates elements of a system embodiment used for a test setup, where the rocking head movement is provided by an inflatable cushion,

Figures 4, 5, 6a, 6b illustrate graphs showing results of tests performed on tinnitus patients,

Figure 6c, 6d, 6e, 6f illustrate graphs showing blood pressure measurement results of tests performed on persons using the test setup of Fig. 3, and

Figure 7 illustrate method steps of a method embodiment.

DESCRIPTION OF EMBODIMENTS

Fig. 1 shows a system embodiment with a control system CS serving to control a stimulation device SD that engages with the head of a patient P so as to perform a rocking head movement R_f2 with a rocking frequency of f2 with a magnitude serving to provide a pleasant stimulation of the person P's vestibular system. The two bold arrows indicate the side-to-side rocking head movement directions, primarily around a vertical V axis, e.g. around the person P's curriculum. The rocking head movement caused by the stimulation device SD may be provided as a force applied to the person P's head primarily in a horizontal H direction. However, in other embodiments, the rocking head movement is provided by a pillow or cushion on which the person P rests, wherein the pillow or cushion has an inflatable compartment which is shaped so as to provide the desired head rocking movements when being repeatedly inflated and deflated. Depending on the shape of the pillow or cushion and its one or more inflatable compartment(s), a side-to-side rolling head movement may be achieved, and/or a up-down nodding head movement, or a combination of the two types of movements.

In the shown embodiment, the system comprises an audio device A D which applies an auditory input A fl in the form of a sound signal to the ears of the person P, either via a loudspeaker or a headphone. The auditory input A fl has an audible feature, preferably in the form of a variying amplitude with a frequency fl, and/or a semantic repetition frequency of fl . Other audible features of the auditory input A fl that may be varied are: frequency content, e.g. frequency filtering (such as cut-off frequency of a low-pass filter varying between a low and a high cut-off frequency). In the shown embodiment, a representation of the auditory input is provided to the control system CS which is then programmed to adapt the control of the stimulation device SD so as to match the frequency f2 of the rocking head movement R_f2 such that f2 = fl/n, where n is an integer. E.g. n=l, 2 or 3, but it may be 4 or more, depending on the auditory input A fl . Preferably, f2 is within 1/20 Hz to 1/4 Hz, more preferably around 1/10 Hz. The auditory input A fl can be based on a repeated natural sound recording which is then played back at frequency fl, e.g. a recording of seaways breaking, birds singing, rain drops falling etc., alternatively synthesized sounds. It may also be a piece of music with a fixed rhythm or with a rhythm varying slowly with time.

The alignment of rhythm, i.e. the synchronization of the two stimulation frequencies fl and f2 as mentioned above serves to distract ther person P's attention toward the two synchronous input modalities: 1) the auditory input, and 2) the vestibular input

(which is provided by a type of tactile, i.e. a third type of input modality). This multi-modal input with a synchronized rhythm has been proven to provide a high degree of distraction which far exceeds that obtained with the auditory and the vestibular stimuli if applied alone, or if applied together but without alignment of at least one audible feature with the rocking head movement, such as alignment of rhythm frequency of both stimuli types as described above. This has been proven to work as an efficient distraction for tinnitus, thus eliviating at least some of the discomfort experienced by tinnitus sufferers.

The system can be implemented in various ways, e.g. with a computer or mobile phone serving the roles of the control system CS and the audio device A D, with a suitable application program and a link to control a dedicated stimulation device SD, e.g. in the form of an inflatable pillow or cushion with a controlable pump system.

Irrespective of the implementation, it is understood that the control system CS may have a user interface allowing a user to vary different parameters of at least one of the stimuli A_fl, R_f2. E.g. the user may switch between different sounds A_fl, e.g. change repetition frequency fl of the sound A fl, change frequency f2, and/or amplitude, and/or direction of the rocking head movement R_f2 etc.

If the system is intended primarly as a help for the person P to fall aspleep, the control system CS may be connected to a sensor serving to indicate a physical parameter to the control system CS about the sleep state of the person P. Upon detection that the person P has fallen asleep, the control system CS may be programmed to fade out, or just shut off after a fixed time, the rocking head movement stimulation R_f2.

Figs. 2a and 2b show graphs on a time scale T(s) with time in seconds on the horizontal, and with a relative amplitude indicated on the vertical axis. Fig. 2a shows the first 60 seconds of an example of a stimulation session of the two stimuli: vestibular stimulation V_S and auditory input A, while the following 60 seconds are seen on Fig. 2b. In the illustrated example, it is seen that the vestibular stimulation V_S in the form of head rocking, starts gently by means of a fade-in phase which lasts for 3 pace cycles. After that, the level of rocking frequency stayed at the specified frequency 1/10 Hz until the end of the experiment, which was a total duration of 10 minutes. The V_S curve is shown as a square curve which represent the electrical signal in the control system, but of course the physical stimulation of the person was provided as a smooth gentle side-to-side movement of the head. The auditory stimulus A was in the form of breaking sea- waves, and the amplitude of this stimulus is seen to coincide with the rocking movement, since the transitions of the rocking head movement signal V_S coincides with the maximum of the periodically varying amplitude of the auditory input A.

Fig. 3 shows a photo of a setup which was used to quantitatively test 20 tinnitus patients in a hospital. The setup has a bed BD with a regular pillow PW under which a standard inflatable air cushion I_C (small camping mat) was positioned. This cushion I_C was inflated and deflated by means of a pump device P_D controlled by a control system in the form of a laptop computer CC. The cushion I_C was positioned under the pillow PW and all elements were hidden inside a regular pillow cover. The pump device P_D and its driver hardware were placed inside a box. The auditory input was provided to the patients by a headphone HP, and the audio signal was also controlled by the laptop comuter CC, and both audio signal and rocking signals were generated by software installed on the laptop computer CC. Using the laptop screen it was possible to follow the driving signals of the audio- vestibular-tactile stimulation device in real time, and the example of audio and vestibular stimuli shown and described in connection with Figs. 2a and 2b are taken from the experiment. The patients were in supine position (on his/her back) on a matrass with the head on the pillow. They responded using questionnaires, and they were asked to rate, on a scale from 1 to 10, their experiences on: tinnitus distress, and the potential aid of the setup to fall asleep. Their breathing rate was recorded during the experiment.

It was found that by offering the combined synchronous auditory and tactile- vestibular stimulation, it was possible to direct the tinnitus patient's attention away from the annoying ringing in the ear(s). The resulting ratings on the questionnaires were normalised relative to the no-stimulation condition by subtracting the rating in the no-stimulus condition from the other conditions. The results are shown in Figs. 4, 5, 6a, and 6b.

Fig. 4 shows the average relative improvement on a scale from 1 to 10 for the various stimulation conditions for the 20 tinnitus patiens (relative to the baseline condition where there was no stimulation). Participants scored the question: "How much is your tinnitus stress at this moment? ". The result 'A' is for auditory stimulation alone, 'V_S' is for the vestibular stimulation alone, and 'V S+A' is for the combined stimulation. As seen, the multisensory condition where the sensory signals were rhythmically synchronous resulted in a 21% improvement relative to no-stimulation, thus a result which clearly exceeds the minor improvements with the auditory and vestibular stimulation applied alone. In conclusion, the inventive system and method is capable of reducing tinnitus stress.

Fig. 5 shows averaged results for the 20 tinnitus patients in the same manner as in Figure 4, but here for the question: "May the audio-vestibular stimulation device potentially help you to fall asleep if you were to use it? ". As in Fig. 4, it is seen that the combined auditory and rhythmically synchronous vestibular stimulation provides a superior result, namely a 27% improvement relative to no-stimulation. Thus, the inventive system and method is capable of helping tinnitus patients to fall asleep.

Figs. 6a and 6b show averaged relative improvement scores from 15 of the tinnitus patients. The results are obtained for two scenarios (as well as no-stimulation):

1) snc - rhythmically synchronous auditory input and and rocking head movements, both with a frequency of 1/10 Hz, and

2) a snc - rhythmically asynchronous auditory input and rocking head movements, where the sound had a frequency of 1/8 Hz, while the head movements had a frequency of 1/10 Hz.

Again, the patients were asked to rate, on a scale from 1 to 10: "May the stimulation device potentially help you to fall asleep if you were to use it? ", and the average score relative to no-stimulation is shown in Fig. 6a, while the similar result for the question: "How much did you enjoy the experience? " is shown in Fig. 6b. As seen, both questions resulted in negative results for the asynchronous stimulation a snc, while the synchrounous stimulation snc results in positive results relative to no-stimulation. Thus, not just any combination of multisensory signals can provide helpful effects. Combination of stimuli presented in a rhythmical synchronous way was preferred over asynchronous presentation. Multisensory congruent stimuli were perceived as more pleasant and relaxing than signals presented in a incongruent way.

The experiments additionally show that the patients' breathing became paced by the rocking pace of the stimulation device, helping them to relax (data not shown).

It was further found using the set up shown in Fig. 3 that with tactile- vestibular stimulation it was possible to cause a lowering of a person's blood pressure and that by offering a combined rhythmically synchronous auditory and tactile- vestibular stimulation an even larger reduction in a person's blood pressure was achieved. Fig. 6c shows the blood pressure of a person measured with a cuff on his arm for several consecutive test conditions as indicated on the x-axis. The upper graph shows the systolic (indicated with "sys") blood pressure and the lower graph the diastolic (indicated with "dia") blood pressure. Fig. 6d shows the measured blood pressure reduction relative to a baseline measurement (first measurement condition shown on x-axis of Fig. 6c: initial state of the person in sitting position, no rocking or auditory stimuli provided, see Fig. 6c). Fig. 6d shows that multi sensory stimulation (combination of synchronized head rocking and auditory stimuli) caused a suprising large reduction in blood pressure. Fig. 6d further shows that a reduction in blood pressure remained when it was measured (in a sitting position) again 5 minutes after the multi sensory stimulation (which was applied for 10 minutes) had stopped. Figs. 6e and 6f show further measurement results obtained with another person. Fig. 6e shows the results of two separate blood pressure measurement series (indicated with series 1 for measurement results "sys2-l", "dia2-l" and series 2 for measurement results "sys 1-2", "dial-2") with the same person resulting in two systolic ("sysl-1" and "sys2-l") and two diastolic ("dia2-l" and "dial-2") blood pressure graphs. In the first measurement series the order of the test conditions was as indicated on the x-axis: starting with a baseline blood pressure

measurement of the person in a sitting position with no stimuli provided followed by a blood pressure measurement of the person in a lying position (see set up shown in Fig. 3). Next the person was measured again in a sitting postion, after which he lied down and received combined synchronous auditory and tactile-vestibular stimulation. After 10 minutes the person's blood pressure was measured again and the person returned to a sitting position. After 5 minutes again the blood pressure was measured. The second measurement series (series 2) had slightly modified order of test conditions: starting again with a base line blood pressure measurement of the person in a sitting position with no stimuli provided but now followed by a blood pressure measurement of the person in a lying position and applied synchronous auditory and tactile- vestibular stimulation. After 10 minutes the person's blood pressure was measured again and the person returned to a sitting position. After 5 minutes again the blood pressure was measured. Then the person lied down again for 10 minutes and received no stimuli and his blood pressure was measured. Next the person returned to a sitting position for a last blood pressure measurement. Fig. 6f shows for both measurement series the measured blood pressure reduction relative to the initial baseline meaurement.

Also these results show that multi sensory stimulation (combination of synchronized head rocking and auditory stimuli) caused a relative large reduction in blood pressure and that a reduction in blood pressure remained when it was measured again 5 minutes after the multi sensory stimulation had stopped.

Fig. 7 shows steps of a method embodiment for providing a healthy person with a pleasant and relaxing sensation, or for reducing discomfort of a person suffering from tinnitus. It is to be understood that the method is an example of a specific method

embodiment for carrying out on an automatic device or system, and not a general description of the method. First step RD Fl comprises reading a pre-stored stimulation frequency Fl, e.g. from a memory. Next step R_H_F1 comprises rocking the person's head with the stimulation frequency Fl with an amplitude so as to stimulate the person's vestibular system. Next step PB A Fl comprises simultaneously playing back an audio signal to the person which is rhythmically synchronous with the rocking of the person's head, e.g. with an audible feature which varies with the same frequency Fl, e.g. a repetition of the same audio sequence with repetition frequency Fl . Next step M S O comprises monitoring the person for onset of sleep, e.g. by reading an input provided from a sensor, e.g. an accelerometer positioned to monitor the person's movements. Finally, the step S ST comprises initiatling a stimulation stop sequence in case it has been detected that the person has fallen asleep, e.g. stopping stimulation after 15 minutes, or initiating a fade-out sequence of gradually reducing audio and rocking movement amplitude until zero value has been reached.

In the following, various parameters of a system or method that can be applied in practical implementation are briefly summed up.

Relating to the auditory input, audio signals can be provided, depending on preference of user, by speaker boxes, headphones, earphones, head-band covering either ear with a small speaker (e.g. SleepPhones ©), or speakers integrated in a pillow. The sound can be any sound, but preferably a sound that has a relaxing effect by itself, e.g. sea-waves, rain drops, singing birds etc. The type of sound can be adjusted and personalised, and audio loudness can be adjusted.

Relating to the rocking head movement stimulation, an inflatable-deflatable rocking pillow positioned underneath the head of the person can be applied. Rocking direction can be up/down (nodding head movements) or left/right (side-to-side head movements), or a combination. The rocking head stimulation amplitude can be adjusted. The user can take on a sleep onset posture on his/her back or on his/her side. A large air pump can be used to inflate and deflate the one or more compartment of the rocking pillow, but the inflation and deflation can also be achieved by a series of micropumps integrated into the pillow to provide the rocking effect.

Relating to the combined auditory input and the rocking head movement, it is preferred that the variations over time of the auditory input and the rocking movement stimulation are coupled, preferable coming from same signal generator, to make them temporally identical. Specifics of the auditory input and rocking head movement signals, such as the frequency and amplitude of the rhythmic variations, may be programmed in advance through a programmable interface. Amplitude of the rocking head movements and loudness of the auditory input preferably increases gently after onset and go gently down at the end. In case of a combined audio -vestibular-tactile pillow, it can be programmed to commence 30 seconds after the user turns it on, so as to enable the user to take the horizontal position in bed; this period may be adjusted. The pillow may be programmed to stop stimulation e.g. 15 minutes after the moment of detection of sleep onset (based on an input provided by a sensor); this period can be adjusted. The user may have the option to control the stimulation period to e.g. 5 minutes after turning the pillow on; this period can be adjusted.

Concerning the waveform of stimulation, it is preferred that the waveform used for the stimuli do not show discontinuities, such as rapid breaks in intensity, for example as exhibited by square wave profiles and saw-tooth profiles, where the intensity changes in an impulsive manner, as this will mask the effect of the periodic variations in trying to focus the attention of the tinnitus patient away from the ringing in their ear(s). A wave form may vary according to a sinusoidal variation, or a zig-zag wave form can be used.

Preferably, the system may comprise an adjustable stimulation frequency so that the user can optimize it for personal use. The range of available frequencies are preferably between 1 Hz (fastest) and 1/10 Hz (slowest). The different sensorial signals preferably vary with the same frequency. However, it is also possible that one or more of the sensorial signals varies with a frequency which is ½, ¼, 1/8 [more generally l/(2^An)] of the frequency of another sensorial signal, as this will also assist in capturing the attention of the tinnitus patient. For example, a repetitive audio signal of a wave breaking with frequency F could be combined with a cushion which rocks the head of the patient every 2 times the wave breaks (1/2 F). Phase differences are not crucial as the brain is flexible to shift signal interpretation in time. For this reason, waveforms which comply with the above embodiments may be unaligned in phase up to at least ¼ of a cycle, maybe even more. In preferred embodiments, both the rocking rate and the sound amplitude variation rate adjust to 90% of the breathing rate to create a paced breathing experience.

To sum up, the invention provides a stimulation system with a stimulator device, e.g. comprising an inflatable/deflatable pillow, arranged to engage with a person's head in order to generate rocking movements of the person's head in a manner stimulating the person's vestibular system, e.g. side-to-side rolls of the person's head. A control system controls the stimulator device in accordance with an auditory input to the person. Preferably, the control system serves to rhythmically synchronize the auditory input and the rocking head movements, e.g. to have the same repetition frequency of between 1/30 Hz and 2 Hz, e.g. 1/10 Hz. The combined synchronous audio and vestibular-tactile stimulation has been shown effective in distracting tinnitus patients form their discomfort, and to help them to fall asleep, and in reducing blood pressure of persons. The auditory input may be a repeated sound signal provided by headphones to the person, e.g. a recording of reaking seawaves, singing birds etc., with a dominating audible feature having a perioditicy aligned with the head movements.

While the invention has been illustrated and described in detail in the drawings and foregoing description, such illustration and description are to be considered illustrative or exemplary and not restrictive; the invention is not limited to the disclosed embodiments.

Other variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims. In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality. A single processor or other unit may fulfil the functions of several items recited in the claims. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measured cannot be used to advantage. A computer program may be stored/distributed on a suitable medium, such as an optical storage medium or a solid-state medium supplied together with or as part of other hardware, but may also be distributed in other forms, such as via the Internet or other wired or wireless

telecommunication systems. Any reference signs in the claims should not be construed as limiting the scope.

Claims

CLAIMS:

1. A stimulation system for providing a person (P) with a stimulation, the system comprising

a stimulator device (SD) arranged to engage with the person's head in order to generate rocking movements (R_f2) of the person's head in a manner stimulating the person's vestibular system, and

a control system (CS) arranged to control the stimulator device in accordance with an auditory input (A_fl) to the person (P), so as to align at least one audible feature in the auditory input (A_fl) with the rocking movements (R_f2) of the person's head.

2. Stimulation system according to claim 1, wherein the at least one audible feature in the auditory input (A_fl) is rhythmically aligned with the rocking movements (R_f2) of the person's head.

3. Stimulation system according to claim 1, wherein the control system (CS) is arranged to control the stimulator device (SD) so as to provide periodic rocking movements

(R_f2) of the person's head with a repetition frequency of between 1/30 Hz and 2 Hz.

4. Stimulation system according to claim 1, wherein the control system (CS) is arranged to initiate a stimulation session by a fade-in phase in which a rocking movement of the person's head is different from later in the stimulation session.

5. Stimulation system according to claim 1, comprising a sensor connected to the control system (CS) , wherein the sensor is arranged to detect a parameter indicative of the person (P) sleeping.

6. Stimulation system according to claim 1, comprising a further sensor coupled to the control system (CS) , wherein the sensor is arranged to measure a blood pressure, respiration rate, heart rate or heart rate variability of the person (P).

7. Stimulation system according to claim 6, wherein the control system (CS) is arranged to control the stimulator device (SD) in dependence of the measured blood pressure, respiration rate, heart rate or heart rate variability of the person (P).

8. Stimulation system according to claim 6, wherein the control system (CS) is arranged to control the stimulator device (SD) so as to provide periodic rocking movements (R_f2) of the person's head with a repetition frequency of about 90% of the value of the measured respiration rate.

9. Stimulation system according to claim 6 or 8, wherein the control system (CS) is arranged to adjust a sound amplitude variation rate of the auditory input (A fl) to about 90% of the value of the measured respiration rate.

10. Stimulation system according to claim 1, wherein the stimulation device (SD) is arranged to provide rocking movements of the person's head in a vertical plane (V).

11. Stimulation system according to claim 1 , wherein the stimulation device (SD) is arranged to provide rocking movements of the person's head in a horizontal plane (H).

12. Stimulation system according to claim 1, wherein the stimulator device (SD) comprises a pillow arranged for the person's head to rest thereon, wherein the pillow comprises at least one compartment (I_C) capable of being inflated and deflated, so as to cause the rocking movements of the person's head, upon successive inflations and deflations of the at least one compartment (I_C).

13. Stimulation system according to claim 12, comprising a pump system connected to the control system (CS), and connected to inflate and deflate the at least one compartment (I_C), wherein the pump system comprises a plurality of micropumps built-into the pillow.

14. Stimulation system according to claim 1, comprising a sound system (A D) arranged to provide the auditory input (A fl) to the person (P).

15. Stimulation system according to claim 1, wherein the control system (CS) is arranged to adjust at least one of: a frequency of an audible feature in the auditory input (A fl), and a repetition frequency of the rocking movements (R_f2) of the person's head.

16. Stimulation system according to claim 1, wherein the control system (CS) is arranged to adjust a frequency of the rocking movements (R_f2) of the person's head in response to a frequency of an audible feature in the auditory input (A fl).

17. Stimulation system according to claim 1, wherein the auditory input (A fl) comprises a repetitive audio sequence with a repetition frequency being an integer times, or an integer fraction of, a repetition frequency of the rocking movements (R_f2) of the person's head.

18. Method for stimulating a person, the method comprising

- rocking the person's head (R H Fl) so as to provide movements of the person's head in a manner stimulating the person's vestibular system, and

controlling said rocking of the person's head in accordance with an auditory input to the person (PB A Fl), so as to align at least one audible feature in the auditory input with the rocking movements of the person's head.

19. Method for reducing discomfort of a person suffering from tinnitus, the method comprising

rocking the person's head (R_H_F1) so as to provide movements of the person's head in a manner stimulating the person's vestibular system, and

- controlling said rocking of the person's head in accordance with an auditory input to the person (PB A Fl), so as to align at least one audible feature in the auditory input with the rocking movements of the person's head.

20. Method of reducing blood pressure of a person, the method comprising - rocking the person's head (R H Fl) so as to provide movements of the person's head in a manner stimulating the person's vestibular system, and