Patent Application
20050201574
1. Field of the Invention
The present invention relates to a system and method for improving the threshold hearing sensitivity and discrimination ability of an individual. In particular, the present invention relates to a system and method for improving threshold hearing and discrimination ability of an individual using high frequency signals to stimulate the cortical auditory and/or other neurons in the individual's brain.
2. Description of the Prior Art
Mild to moderate sensorineural hearing loss is a common affliction. Prior to the present invention, there has been no effective cure for such hearing loss, with current treatments being limited to the use of amplifying prosthetics, i.e., hearing aids. Sensorineural hearing loss refers to hearing loss that involves the sensory and neural components of the ear such as occurs in inner ear hearing losses.
Hearing loss is sometimes accompanied by tinnitis, which maybe defined as any ringing for which there is no external source. Tinnitis is considered a phantom sound which arises in the brain and not actually in the ears as it appears to subjectively. For example, a ringing, buzzing, whistling, or roaring sound may be perceived as tinnitis. Tinnitis can be continuous or intermittent, and in either case can be irritating to one who has such an affliction. Tinnitis has been successfully treated by applying ultrasound to the head of a patient as described in U.S. Pat. No. 6,394,969 to Martin L. Lenhardt, which is incorporated herein by reference.
Nevertheless, there is a need for an effective treatment for hearing loss, including the treatment of hearing loss that is accompanied by tinnitis, without the use of amplifying prosthetics. This need is achieved for the first time by the present invention.
Various embodiments of the invention are directed to methods for improving the hearing of an individual by applying a vibration stimulus between about 2 kHz and about 5 MHz to the individual by means of a transducer (e.g., a piezo transducer) for a period of time, such as about one hour. This period may be set in advance or adjusted during treatment by a clinician or the individual. The method may be combined with the application of a sonic vibration stimulus between about 2 kHz and about 20 kHz to the individual by means of headphones placed on or near the ears. Alternatively, the vibration stimulus may be applied by means of headphones alone. Without being bound by any theory, hypothesis or putative mode of action, the vibration stimulation of the brain of the individual is believed to cause neural reprogramming of high frequency sensitive neurons, thereby improving threshold hearing sensitivity.
Various embodiments of the invention are also directed to methods for treating individuals having sensorineural hearing loss (i.e., partial sensorineural hearing loss), which include applying a transducer, such as a piezo transducer, to the individual's head or neck, and connecting the transducer to a vibration signal so as to provide a vibration stimulus between about 2 kHz and about 5 MHz to the individual for a period of time, such as about thirty minutes to about one hour. This period may be set in advance or adjusted during treatment by a clinician or the individual. Alternatively or in addition, headphones may be placed on, in, or near the individual's ears and connected to a sonic vibration signal so as to provide a sonic vibration stimulus including frequencies between about 2 kHz and about 20 kHz is applied to the individual for a period of time, such as one hour. This method of treatment may be repeated periodically as necessary to maintain the level of hearing improvement.
Various embodiments of the invention are directed to systems and devices for detecting and/or treating hearing loss by applying a vibration stimulus to an individual.
The above-mentioned object and advantages of the invention will become more fully apparent from the following detailed description when read in conjunction with the accompanying drawings, with like reference numerals indicating the same or like parts throughout, and wherein:
Various embodiments of the invention are directed to methods, apparatus and systems for treating sensorineural hearing loss, particularly high frequency hearing loss. The incidence of sensory hearing loss tends to increase with age, thus affecting much of the population. Age, drugs and/or intense sound can permanently damage the hair cells within the ear that sense sound waves. Such damage often leads to a loss of high frequency stimulation in the cochlea, which leads to a reduction in the amount of neural signals (i.e., neural information) provided to the cortex. Such sensory hearing loss may be characterized by increases in the threshold volume at which an individual perceives tones at different frequencies. An example of a patient population suffering from such effects are those individuals exhibiting mild to moderate sensorineural hearing loss. Another example patient population are those suffer partial hearing loss and loss of frequency, time and intensity discrimination.
It has been shown that musicians exhibit expanded auditory cortex and related neural structures with musical training. This is the likely reason for their improved detection and discrimination of sound. Similarly, it has been found that a reduction in the amount of high frequency sound detected in the cochlea may lead high frequency-sensitive neurons to reprogram to be sensitive to lower frequency sound by shifting their best frequency response toward lower frequencies. It is believed that when there is high frequency hearing loss without tinnitis due to damage in the cochlea, auditory neurons reprogram to achieve best frequency responses below the band of frequency loss in the cochlea. Further, a reduction in high frequency neural signals received in the cortex may lead to changes in synaptic connections and/or a shrinking of the population of neurons processing high frequency sound. Such adaptive reprogramming of cortex neurons and reductions in the population of high frequency sensitive neurons in the cortex may lead to further high frequency hearing loss. References herein to reprogramming of neurons means the natural adaptation that neurons and neural structures exhibit in response to training, stimulation or lack of stimulation.
The present invention stimulates the cortex by applying high frequency or ultrasonic vibrations (approximately 2 kHz to approximately 5 MHz) to the head (neck or body) of an individual in order to prevent or reverse the deleterious programming of high frequency sensing and processing neurons to lower frequencies. As used herein, “vibration” encompasses periodic movement of a physical surface (e.g., the active face of a transducer) and/or a nongaseous fluid (e.g., water or blood) that when placed in contact with the head of an individual are sufficient to induce pressure pulses within the cochlea and/or the brain of the individual. A single tone vibration may be characterized in terms of its frequency (i.e., a vibration has a frequency) and amplitude (e.g., volume). Further, a vibration stimulus may comprise the combination two or more vibration frequencies, such as two or more tones or chords, e.g., music. A vibration stimulus applied to the skin may be perceived as a vibration or as an audible sound for high frequency signals or may be inaudible ultrasound. Such vibrations are referred to herein as “stimulus” or “vibration stimulus.” Block diagrams of exemplary systems suitable for applying such stimulation to individuals are shown in
Vibration stimulus applied to the head or neck of an individual according to various embodiments of the present invention is believed to lead to reprogramming of cortex neurons that resets their best frequency response. It is possible that such reprogramming occurs neurochemically by changing inhibitory inputs to cortical cells. Consequently, the simulation is believed to cause adaptive cortical neural reprogramming, which may be referred to as cortical reorganization or remapping, that leads to improved sensitivity to high frequency sound and discrimination (i.e., the ability to detect high frequency sound at lower threshold volume). Further, it is believed that such reprogramming occurs rapidly, taking place within less than 1 day, likely within approximately 1 to 3 hours, and possibly as rapidly as within 5 to 35 minutes, approximately.
The present invention also may simulate the cilia of hair cells within the cochlea, and also the vestibular system; canals, utricule and/or saccule. It appears that vibration stimulus in the form of high frequency noise or ultrasound applied to the head of an individual is demodulated in the cilia of hair cells due to the ultrasonic resonance of the cilia. Thus, movement of endolymph caused by a compressive intracochlear ultrasonic wave may induce vibration of the cilia at their ultrasonic resonance. This may have rejuvenative effects on the hair cells by way of the direct stimulation. Further, stimulation of nearby hair cells that may not be damaged may also stimulate adjunct areas in the central nervous system, which may send additional stimulating signals to the cortex.
Treatments according to various embodiments of the present invention may be repeated periodically. Since it is believed that hearing threshold and discrimination improvements result from reprogramming of neurons in the cortex and/or rejuvenation of hair cells and neurons in the cochlea, periodic repetition is expected to increase the effectiveness and lasting benefits of the treatment. Further, periodic treatment may be effective in preventing or reducing the reprogramming of high frequency sensitive cortical neurons that occurs due to reduced stimulation provided by damaged high frequency hair cells in the cochlea. Additionally cortical cochlear feed forward and feed back networks may modulate the receptiveness of the ear and brain.
Since high frequency sensory hearing loss may have its roots in degenerated or damaged high frequency hair cells within the cochlea, listening to high frequency sound, referred to herein as “airborne conduction,” may not provide sufficient stimulation to cause reprogramming of neurons and training of the cortex to detect high frequency sound. To address this physical limitation, various embodiments of the present invention provide vibration stimulus to the cochlea and/or cortex by applying high frequency and/or ultrasound vibration energy directly to the head or neck of an individual in a manner that induces conduction through the bones and/or fluids (e.g., blood, muscle, brain tissue, etc.). Vibration stimulus may be applied to the individual by placing a transducer in direct physical contact with the scalp or skin. Alternatively, vibration stimulus may be applied through nongaseous fluids (e.g., water) in direct contact with the individual's head, neck and/or ears. It is believed that vibration stimulus so applied is provided into the individuals brain and/or inner ear by conduction through bones of the head (referred to as bone conduction), through fluids (e.g., blood) and tissues (e.g., muscle, brain tissues) of the head and neck (referred to herein as fluid conduction), or through both bone conduction and fluid conduction.
Mild hearing loss and noise exposure is often accompanied by tinnitis. Tinnitis can be described as a phantom sound (e.g., whistling, buzzing, ringing, etc.) that arises without any external stimulation. Often the source of tinnitis is assigned to the ear by an individual because it “sounds” like a sound in that it has the pitch, loudness and timbre of a sound. Tinnitis can be matched in quality to an external sound, and it is often associated with one ear or the other, or both ears.
There are researchers who pose a central origin to tinnitis, with that central origin being beyond the ear and in the brain. For example, an article by Lockwood et al., published in 1998, found widespread activation of the primary cortex contralateral to the ear as being the source of tinnitis. In other words, the source of tinnitis may actually be cortical and not in the ear. Similarly, in “Ultra-High Frequency Acoustic Stimulation and Tinnitis Control: A Positron Emission Tomography Study,” The International Tinnitis Journal, Vol. 10, No. 2, 2004, pp. 113-126, Lenhardt, et al. found activation of the primary cortex and other sites within the brain as the source of tinnitus. This is a reasonable view since it has been demonstrated that auditory cortical neuron reprogramming in the ear is not capable of providing frequency-specific stimulation. Further, Lenhardt et al. reported that ultra-high-frequency external acoustic stimulation quieted brain activity in the sites of tinnitus. Thus, the reprogramming of the cortex in response to high frequency signal deprivation due to loss or damage of high frequency sensitivity of cochlear hair cells may well produce tinnitis as a by-product.
This view is supported by position emission tomography (PET) scans of individuals with tinnitis. The neural imaging data show that tinnitis activates the primary auditory cortex contralateral to the ear in which the tinnitis is localized, with that area activated being broader than that activated by sounds of similar frequency.
While there may be disagreement about the site of tinnitis (ear versus brain), most researchers agree that tinnitis and hearing loss often are associated. Therefore, the treatment of mild to moderate high frequency hearing loss should also address tinnitis associated with that hearing loss. Further, since a treatment that also suppresses tinnitis would remove the tinnitis noise that tends to impede perception of high frequency sound, treatments according to various embodiments of the present invention are expected to provide even greater improvements in threshold hearing sensitivity of patients with both hearing loss and tinnitis.
To determine a treatment for sensorineural hearing loss and potentially associated tinnitis, one has to understand the workings of the inner ear and the brain. External sounds activate both primary cortices, and each cortex is connected to a respective ear via a descending auditory nervous system. When auditory stimulation is applied using air conduction alone, the brain will actively try to reduce the amount of auditory stimulation arising up the auditory pathway by activating the descending auditory neural track. The result is that the brain will try to turn down the auditory stimulation, limiting the effectiveness of treatments using air conduction in stimulating cortical neurons. Further, energy from sounds above the middle ear resonance frequency, which is on the order of 3,000 Hz, are impeded within the middle ear due to interference from reflected waves. As a result, what is needed is a stimulus that is sufficiently salient to stimulate the high frequency responsive neural structures of the cortex and/or cochlea, but is not treated as an unwanted sound signal that will be inhibited by the brain. A stimulator that provides such a stimulus will be effective in terms of auditory cortical activation. Such a stimulator will be effective with individuals having hearing loss due to degraded cochlear hair cells. Such a stimulator will also be effective in treating individuals having hearing loss and associated tinnitis.
High frequency or ultrasonic noise or tones provide a stimulus that will meet all of the above criteria, and therefore can be used in the systems and methods for treating sensorineural hearing loss according to various embodiments of the invention. Such noise or tones can be made up of any part of the spectrum from about 2,000 Hz up to about 200,000 Hz (approximately 2-200 kHz). In various embodiments, the ultrasonic noise band may extend from about 2,000 Hz to about 20,000 Hz (approximately 2-20 kHz), from about 6,000 Hz to about 16,000 Hz (approximately 6-16 kHz), or from about 8,000 Hz to about 14,000 Hz (approximately 8-14 kHz). In another embodiment, vibration stimulus in a frequency band of from about 200,000 Hz (200 kHz) to about 5 MHz may be used, with or without the other ranges in the aforementioned embodiments. Alternatively, single or multiple tones in the ranges provided in the aforementioned embodiments may be used instead of noise. In another embodiment, a single tone or noise (e.g., pseudo-randomly varying tones) in a range of from about 2 kHz to about 20 kHz may be used, whereby this frequency range corresponds to an upper audio frequency range. In each of the aforementioned vibration stimulus frequency ranges, the tonal or noise stimulation may be applied directly to the head or neck of an individual such as via a transducer placed in direct contact with the skin or scalp, via a fluid in contact with the skin or scalp, or alternatively in combination tones or noise applied via both a transducer and via a fluid in contact with the skin or scalp. As used herein, the term “about” in the context of numerical values and ranges refers to values or ranges that approximate or are close to the recited values or ranges such that the invention can perform as intended, such as having a desired degree or extent of cochlear and/or cortical stimulus, as is apparent from the teachings contained herein. Thus, this term encompasses values beyond those simply resulting from systematic error.
The spectral energy that may be applied to an individual to treat sensorineural hearing loss is from about 2 kHz upward and can be a single tone, multiple tones or filtered noise. Further, it can be continuous or pulsed, and/or modulated with an audible signal such as music. The spectral energy is preferably delivered near or at no more than about 20 dB or so above the individual's threshold hearing level (e.g., between threshold and 20 dB above threshold).
Under various embodiments of the present invention, delivery of vibration stimulus to an individual may be by a vibrator placed directly on the skin of the head or neck of the individual receiving treatment. As used herein, a vibrator is a device for applying audio range to high frequency vibrations to an individual directly, such as directly to the skin, or indirectly, such as via an intermediary fluid like water or via the air conduction (i.e., sound). One embodiment of a vibrator is a piezoelectric transducer, such as transducers similar to those used in transcranial Doppler insonation. By way of example but not by way of limitation, a suitable transducer is illustrated in
Under various embodiments, delivery of vibration stimulus to an individual may be via a vibrator featuring fluid placed in contact with the head or neck of the individual receiving treatment. As but one example, a portion of the patient's head, such the back of the head up to and potentially including the ears, may be placed under a fluid, such as water, in which a transducer is submerged. The relatively strong vibrational coupling between a fluid, such as water, and the patient's tissues will result in a large fraction of the vibration energy being transmitted into the patient's head. In various embodiments employing fluidic coupling of vibration stimulus to the patient, fluid filled earphones such as shown in
In the case where MHz tonal or noise frequencies are used according to an embodiment of the invention, the stimulus may be provided in a pulsed manner. The rate of pulsing is not critical, but a slow rate of pulsing, such as a rate from about 1 to about 10 Hz, is preferred. Because the stimulator according to various embodiments of the invention is high pitched and broad in spectrum, the high frequency sensitive area of the cerebral cortex will be stimulated. Since the delivery intensity will be low, the minimal energy (i.e., threshold) auditory sensitivity of an individual receiving such treatment will be improved. Since ultrasound is difficult to detect by air conduction, the stimulator according to various embodiments of the invention may be personal and inaudible to others who may be nearby the person undergoing treatment. A MHz pulser, to be used to deliver MHz noise signals according to the third embodiment, will preferably be delivered to the skin over the foreman magnum (back of skull by the neck).
High frequency and ultrasound signals applied to the head or neck affects not only a wide area in the ear (sending afferent information to the auditory cortex), but they also affect the brain itself. Ultrasound actually pulses the brain since the brain's fundamental resonant frequency is in the low ultrasonic range to the high audio range (determined by the diameter of the brain and sound velocity in water).
Pulsed ultrasound noise according to an embodiment will also send the brain into oscillation at its resonant frequency, and thus is also a viable means of stimulation according to an embodiment of the present invention. Delgado and Monteagudo (1995) demonstrated that low frequency amplitude-modulated (AM) ultrasound can effectively stimulate cortical neutrons, which may be used to stimulate brain tissues for brain modification. The present invention also stimulates cortical neurons, but for the purpose of inducing neural reprogramming to improve the perception of high frequency sound, which was not recognized by Delgado and Monteagudo.
Therefore, various embodiments of the present invention provide for the use of high frequency or ultrasound to treat sensorineural hearing loss by stimulating any remaining high frequency area in the ear and by acting on cortical auditory neurons in the brain. Thus, the various embodiments of the present invention deliver high frequency or ultrasonic energy occipitally to the patient, thereby stimulating the high frequency areas of the cochlea and cortices. Other embodiments make use of direct stimulation via bone conduction to provide a high frequency audiometer that overcomes problems posed by ear canal acoustics and provides measurements suitable for designing personalized treatments for high frequency hearing loss.
Another embodiment uses an amplitude modulated carrier signal that is solely in the upper audio range in order to provide high frequency stimulation to an individual. This embodiment has an advantage in that, due to the use of a lower frequency range, the power consumption is less than it is for the other frequency ranges used in other embodiments. In this embodiment, the treatment signal may be provided to the patient via fluid filled headphones or a fluid filled neck ring, either alone or in combination with a transducer applied to the head or neck. Since the high frequency sound detected in the cochlea will result in stimulation of the high frequency neurons within the cortex, leading to neural reprogramming, this embodiment may have similar beneficial effects on threshold hearing sensitivity. This conclusion is supported by recent tests on mammals (ferrets) that noted changes in cortical neural structures following training with high frequency signals, as reported in The Acquisitive Auditory Cortex by John C Middlebrooks and Rapid Task-Related Plasticity of Spectrotemporal Receptive Fields in Primary Auditory Cortex by Jonathan Fritz, Shihab Shamma, Mounya Elhilali & David Klein, published in Nature Neuroscience Vol. 6, No. 11, 2003, pages 1122-23 and 1216-1223, respectively.
In one or more embodiments, signal transmission is by way of double sideband modulation (suppressed carrier). Full amplitude modulation (full AM carrier plus both sidebands) or single sideband modulation (either upper or lower sideband with the carrier and the other sideband suppressed) can alternatively be utilized. Modulation depth generally does not exceed about 90% though a modulation of up to about 100% can work under ideal conditions, and the energy does not exceed about 15 kPa (measured in water at 3.5 cm). Total power is preferably limited to about 30 mW cm2. Commercially available piezoelectric transducers may be used to deliver the ultrasound in vibratory form to the patient's head or to a fluid in contact with the patient's head. The precise level of energy (not to exceed about 15 kPa) may be determined for each patient during testing of each patient, or based upon predetermined values. Ultrasound signals may or may not be audible during therapy. Sound pressures may be maintained at or below comfortable listening levels and in compliance with federal safety standards on sound exposure.
Referring back to
A further embodiment of the invention employs music as part of the vibration stimulus, which may be in the form of pulsed vibration stimulation. Within the vibration source 310, a music signal may be filtered, and then multiplied by a high or ultrasound frequency vibration signal, which corresponds to a carrier having a frequency value within the range of from about 2 kHz to about 200 kHz. The carrier may be tonal (e.g., one or more single frequency tones between about 10 kHz and about 20 kHz), noise (e.g., white noise between about 2 kHz to about 20 kHz), or a swept carrier in the frequency range from about 2 kHz to about 200 kHz, more preferably between about 5 kHz to about 20 kHz. The music may be pulsed in such a fashion as to be culturally agreeable to the listener, since music is (typically) meant to be enjoyed when heard. The output signal, which is the filtered music multiplied with the carrier (or plurality of carriers, if more than one tone is used) in the range of from about 2 kHz to about 20 kHz, may not be recognizable as music, but the output signal has the temporal essence or timbre of music.
In an alternative implementation of this embodiment described above, the stimulus signals are recorded on a suitable recording device or medium, such as by way of example but not by way of limitation, a digital or analog magnetic tape, video cassette recorder (VCR) tape, magnetic disc, compact disc (CD), digital video disc (DVD), an MP3 player or a player using other compression algorithms, a computer hard drive, a disk drive of a server computer hosting an Internet website, random access memory (RAM), read only memory (ROM), flash memory or erasable programmable read only memory chips, or other electronic, magnetic and/or optical storage device or technology that will be developed in the future, with segments, files or tracks varying in intensity level. Using a CD as an example, the listener may adjust the volume of the stimulation by selecting the appropriate track of the CD.
Referring to
Low frequency stimulus signals can be combined with ultrasound stimulus by amplitude modulating the ultrasound signal by very low audio frequencies, for example, from about 1 Hz to about 50 Hz. The perception of such a stimulus is of high pitch sound having a low frequency periodicity. The periodicity can be increased or decreased by changing the modulating audio frequency. Thus, using an apparatus and methods according to various embodiments of the invention, the ultrasound treatment for high frequency hearing loss can be tuned to also provide low frequency stimulation, which may be beneficial for also treating or suppressing low frequency tinnitis often seen with the hearing loss. Further, auditory nerve low frequency synchronous firing stimulation may also be incorporated in the ultrasound treatment regime according to various embodiments of the invention.
A site of action of the treatments according to various embodiments of the present invention appears to be the hair cells in the inner ear when a MHz amplitude modulated signal is applied, in which an audio tone is reintroduced by demodulation. In the ultrasound stimulus methods and apparatus according to various embodiments of the invention, demodulation does not appear to take place in the cochlea, but instead, the site of action appears to take place in the cilia of the hair cells. The cilia have ultrasonic resonance, and a movement of endolymph by a compressive intracochlear ultrasonic wave may have rejuvenative effects on the cell directly. The effect may also occur in the vestibular system, which is also activated by ultrasound. Stimulation of nearby cells (with respect to those injured) may also stimulate adjunct areas in the central nervous system, thereby providing additional stimulation to neurons in the cortices.
Referring to
In a configuration of the transducer utilized with the present invention, an oscillator (not shown) delivers a high ultrasound frequency, e.g., about 20 kHz frequency, at low level to the transducer 410. The high ultrasound frequency activates, or stimulates, the vibratory motion such that less energy is required at frequencies near the fundamental and first harmonic to produce a useful amount of displacement at the skin (e.g., approximately 1 micrometer displacement), than what would be required if the high ultrasound frequency was not provided to the transducer 410. Energy savings may be achieved using a 200 kHz tone in conjunction with the audio or low ultrasonic frequencies that are supplied in accordance with the present invention so as to mask or suppress tinnitis. Other high ultrasound frequencies besides 200 kHz may be utilized to achieve this energy savings (for example, using a high ultrasound frequency in the range of from about 100 kHz to about 500 kHz).
b shows an alternative vibrator in the form of a fluid filled neck ring that can be utilized in any of the various embodiments of the present invention, in order to provide a vibration stimulus to a patient's head by way of bone and/or fluid conduction. In this embodiment a fluid filled neck ring 700 illustrated in
An example of an embodiment utilizing music (or any complex acoustic pattern) to modulate a high frequency or ultrasound carrier signal to provide a treatment vibration stimulus, employs two tones used as the carrier signal, such as one at about 12 kHz and the other at about 16.384 kHz. Of course, other frequencies or number of tones may be chosen within an acceptable range (e.g., from about 10 kHz to about 20 kHz). Two frequencies may be chosen so as to better support music as an input signal. Music with an even spectral spread at a substantially constant volume may be preferable for use in this embodiment to provide an effective and more pleasing stimulus.
As an optional element, a final adjustable gain stage 794 may be utilized to mix in some unprocessed base band signal 792 with the signal 790, if desired. For example, a 200 kHz (approximate) tone can be mixed with the signal 790 at optional gain stage 794. The 200 kHz tone activates the transducer that receives the output signal, to cause the transducer to operate at one of its higher resonance frequency modes. This results in less energy in the lower frequency range (e.g., processed noise) to be detected by the patient. The use of such a high frequency tone may not be utilized in the embodiments that use air conduction to provide the treatment.
The final output signal 796 may be recorded onto a suitable signal storage medium which may include by way of example but not by way of limitation CD, DVD, magnetic tape, magnetic disc, VCR, random access memory (RAM), nonvolatile electronic memory (e.g., flash memory) in an MP3 player, and/or other storage medium or technology that will be developed, for playback through a transducer treatment device, fluid filled headphones or a fluid filled neck ring according to various embodiments of the invention.
Tests were performed on volunteers to confirm the effectiveness of treating mild to moderate (i.e., partial) hearing loss in patients without tinnitis according to embodiments of the present invention. Four individuals exhibiting mild sensorineural hearing loss without tinnitis were first tested to determine their threshold hearing sensitivity over the auditory range. The composite results of this testing are shown in
Tests performed using the present invention on individuals suffering from mild hearing loss and tinnitis were also conducted which demonstrated improvements in threshold hearing sensitivity. Moreover, by suppressing tinnitis, the hearing improvements afforded by treatments according to the invention are expected to be even greater for patients exhibiting both hearing loss and tinnitis. Specifically, six (6) individuals exhibiting mild sensorineural hearing loss and tinnitis were first tested to determine their threshold hearing sensitivity over the auditory range. These individuals were then treated twice per week for eight weeks with a one-hour session of ultrasound stimulation according to an embodiment of the present invention using bone conduction stimulation at high frequencies (about 2-about 20 kHz) provided by a transducer applied to the head of the individuals. The amplitude spectrum of high frequency noise applied to these individuals is shown in
The apparatus and systems described herein are suitable for use in improving the hearing of an individual, particularly the threshold hearing of high frequency sound. Specifically, to improve the hearing of an individual, a vibration stimulus between about 2 kHz and about 5 MHz is applied to the individual, preferably to the head or neck by means of a transducer (e.g., a piezo transducer) applied to the skin or scalp for a period of time, such as about one hour to about three hours, preferably to approximately one hour or less and most preferably between about 35 minutes and about one hour. Alternatively or in addition, a vibration stimulus with frequencies between about 2 kHz and about 20 kHz is applied to the individual by means of fluid filled headphones or fluid filed neck ring placed on or near the ears.
The apparatus and systems described herein are also suitable for use in treating individuals having partial sensorineural hearing loss, particularly hearing loss in the high frequencies. Specifically, to treat a person having partial sensorineural hearing loss, a transducer, such as a piezo transducer, is applied to the individual's head or neck, and then a vibration signal is connected to the transducer so as to provide a vibration stimulus between about 2 kHz and about 5 MHz to the individual for a period of time, such as approximately one hour. Alternatively or in addition, fluid filled headphones or a fluid filled neck ring are placed on, in or near the individual's ears and connected to a vibration stimulus signal so as to provide a vibration stimulus including frequencies between about 2 kHz and about 20 kHz for a period of time. The period of time is up to about three hours, more preferably approximately one hour or less. This method of treatment using the described systems may be repeated periodically as necessary to maintain the level of hearing improvement.
While preferred embodiments have been described herein, modification of the described embodiments may become apparent to those of ordinary skill in the art, following the teachings of the invention, without departing from the scope of the invention as set forth in the appended claims. For example, the pulsing as described in one embodiment, may also be utilized in any of the other embodiments, so as to stimulate the brain at one or more of its resonant frequencies. Also, all of the components necessary to provide the treatment, may be accommodated on a single printed circuit board, to thereby make a small-sized treatment device, including portable devices that may be battery powered. A signal output from the printed circuit board may be stored directly on the board in random access memory (RAM), nonvolatile electronic memory, or on any form of digital storage medium or method that may be accessed by the device or a microprocessor, with may include by way of example but not by way of limitation a CD, DVD, magnetic tape, magnetic disc memory, VCR tape, electronic memory in a suitable format, such as for example digital MP3 format or other compression algorithms, and/or other storage technology that will be developed in the future, for playback on a device capable of accessing the digital storage medium, such as a CD player, magnetic tape player, or MP3 player coupled to headphones, a fluid filled neck ring or a suitable transducer to provide an inexpensive treatment for sensorineural hearing loss that may be applied in a doctor's office or at a patient's home or workplace.
In another embodiment, the vibration stimulus is stored in the form of vibration stimulus signals on a suitable random access memory (RAM), nonvolatile electronic memory (e.g., flash memory), optical, magnetic (e.g., magnetic tape or magnetic disc) or other storage media, including storage technologies that will be developed in the future. The stored stimulus signals may be retrieved by the appropriate storage media reading device or player, which may include by way of example but not by way of limitation, a CD player, a DVD player, a magnetic tape player, a magnetic hard drive, a VCR, a web-based server, laptop or notebook computer, an MP3 player or a player using other compression algorithms, a personal computer, a personal digital assistant (PDA) and/or other devices and technologies that will be developed in the future. Further, the appropriate storage media reading device or player may be coupled to a telecommunications system, cable, computer network, satellite telecommunications link, telephone link, wireless data link, or other data link to provide the stimulus signals to a remote location where they may be received on a suitable reception device, such as a cellular telephone, computer, laptop or notebook computer, PDA, radio, or other technology receivers for providing the stimulus signals to a transducer and/or fluid filled headphones or a fluid filled neck ring. The device player (e.g., CD player, DVD player, VCR, MP3 player, laptop or notebook computer, personal computer or PDA) may be used with or without a separate transducer disposed on the neck or head of the user to provide the stimulation treatment signals by way of bone or fluid conduction. In this embodiment, a doctor can provide access to the vibration stimulus signals by providing the individual with an individual prescribed (personalized) treatment stored on a signal storage medium, e.g., linear or non-linear storage media, a optical disc, CD, DVD, magnetic tape, VCR, magnetic disc, magnetic optical disc, random access memory (RAM), EPROM or other storage technology that will be developed in the future, the storage medium containing the signals that the individual can then use to receive treatment using an appropriate player device.
In another embodiment, the vibration stimulus is stored in the form of vibration stimulus signals on a suitable electronic, optical, magnetic or other technology storage media that will be developed in the future, with the storage media coupled to a computer accessible to the patient via a telecommunications system, such as, for example, a computer or web-based server hosting a website connected to the Internet. A system according to this embodiment is illustrated in
Referring to
In a configuration of the systems and methods contemplated under this embodiment, treatment can be dispensed from a central treatment service over the Internet at the time and place chosen by a patient, audiologist or attending physician. In one configuration of this embodiment the patient may be required to pay a fee in return for receiving the treatment stimulus signal, such as by completing an electronic funds transfer or credit card transaction via an Internet website. This embodiment encompasses Internet-based pay-per-treatment access to stimulus signals and/or Internet-based on-line hearing loss treatment prescription fulfillment services, such as where the patient completes an Internet electronic payment of a fee (e.g., by completing a credit or debit card transaction) before receiving the treatment signal via the Internet. Alternatively, an Internet website allowing access to a vibration stimulus signal may monitor the duration that an individual accesses a stimulus signal and then generate an invoice based upon the duration of usage.
Another example embodiment of the present invention is illustrated in
Since many of the components in this embodiment may be fabricated as integrated circuits, the auditory stimulator device can be assembled into a portable unit for convenient use by a patient. An example of such packaging is illustrated in
In addition to components required to generate the stimulus signal, the auditory stimulator device 1400 may include circuitry for transmitting data to and receiving data from an external computer. Such circuitry may include a wireless transmitter/receiver (transceiver) 1413, such as for example an infrared (1R) data link or radio frequency (RF) data link (e.g., for example, a Bluetooth or 802.11g wireless data link) as are well known in the electronic arts, or other wireless data communication technology or standard that will be developed in the future. In addition to the transmitter 1413, the auditory stimulator device may include circuitry (not shown) associated with the wireless transceiver for handling data communications tasks. A wireless transceiver 1413 enables the auditory stimulator device to receive configuration and personalizing data from a clinician, including a personalized stimulus signal and treatment profile, software updates from a clinician or manufacturer, music or language files that may be mixed with the stimulus signal or played alone (e.g., for entertainment), or data associated with other functions. A compatible transceiver coupled to a personal computer connected to the Internet would permit a user to send and receive data and software between remote sources (e.g., clinician or manufacturer servers) and the auditory stimulator device in a manner similar to that illustrated in
A signal generator (e.g., a digital sound playback chip 1302, 1407) may be a custom chip containing circuitry configured to receive data from a stimulus data store and generate audio frequency signals consistent with the intended auditory stimulus treatment. Such a custom chip may comprise one or more digital signal processors, memory, signal conditioning circuits, amplifiers and other circuits as are well known in the electronic arts. Alternatively, a signal generator (e.g., digital sound playback chip 1302, 1407) may be one or more programmable digital signal processor chips as are commercially available, such as digital signal processor chips used in MP3 players. A signal generator based upon one or more programmable digital signal processors will operate with a sampling rate of about 96 kHz or more for generating stimulus signal frequencies in the range of about 21,000 Hz to about 42,000 Hz, and of about 44 kHz or more fore generating stimulus signal frequencies below about 21,000 Hz.
The foregoing description and
In operation, a user of an auditory stimulator device as illustrated in
As mentioned above, a first step in developing the treatment stimulation signal involves testing an individual to determine his/her hearing threshold profile. This may be accomplished by a clinician, such as an audiologist, using an audiometer. An audiometer is basically an audio frequency generator capable of generating periodic (e.g., sinusoidal) signals of controlled amplitude (i.e., volume) whose frequency ranges from about 125 Hz to about 20000 Hz suitable for driving headphones to produce sounds in that frequency range. Typically, the individual being tested wears headphones to listen to the generated tones, and presses a button when he/she hears each tone. Typically, testing is accomplished at a number of discrete frequencies across the audible range, such as, for example, 250, 500, 1000, 2000, 3000, 4000, 6000 and 8000 Hz. The amplitude (i.e., volume) of each tone is raised and lowered in response to the individual pressing a button when each tone is perceived in order to determine a hearing threshold or hearing level (HL) for that tone. This process is repeated in each ear and for each tone and then graphed to provide a hearing level profile. An example hearing level profile is illustrated in
While human hearing extends up to about 20,000 Hz, testing of the hearing levels above about 8000 Hz is rarely conducted due to the acoustical interference that occurs in the ear canal at high frequencies. Acoustical interference results from the size and shape of the ear canal, occurring when the frequency of a tone is such that one-fourth of the tone's wavelength is similar to the length of the ear canal. Such interference reduces the amplitude of high frequency sound reaching the ear drum in an unpredictable manner, and making it nearly impossible to accurately measure hearing thresholds by air conduction audiometric methods.
According to an embodiment of the present invention, the difficulties in testing individuals at high frequencies can be overcome by utilizing a piezo transducer applied to the neck or head to supply the test signals via bone conduction. This method bypasses the outer and middle ear and applies the vibration directly to the inner ear. A comparison of the air conduction and bone conduction hearing level (HL) thresholds of a typical individual are illustrated in
For frequencies in the range of about 6000 to about 8000 Hz, the output of some audiometers may be supplied directly to the transducer. However, for hearing level testing at higher frequencies, driving the transducer directly will not yield reliable results due to the differences in sound conduction to the ear drum via air (air conduction) and bone (bone conduction) at such frequencies. To accommodate this difference in conduction, an embodiment of the present invention provides a matching circuit 1700, a nonlimiting example of which is illustrated in
Referring to
The variable resistors may be adjusted during a calibration procedure for a particular audiometer or make/model of audiometer. The appropriate resistance can be determined by measuring the energy reaching the inner ear for each frequency by both air and bone conduction and calculating the ratio between the measured values. Quality reference standards may be established for bone conduction at selected frequencies, such as for example 12,000 and 16,000 Hz, which relate to air calibration standards for those frequencies.
In another embodiment of the present invention, the output 1708 of the matching circuit 1700 may be connected to the input of an auditory stimulator system according to the various embodiments of the present invention. This configuration is illustrated in
In a further embodiment, the signal generator functions of an audiometer may be combined with or incorporated into the functionality of the auditory stimulator itself. For example, the frequency and amplitude control circuitry of an audiometer can be implemented within a single integrated circuit (an “audiometer chip”) that can function in conjunction with other components of the auditory stimulator device to permit the device to function as an audiometer using some or all of the components associated with the stimulator functionality. Additional memory or amplifier chips necessary to accomplish audiometer functions may also be incorporated into the auditory stimulator device circuitry. Optionally, the audiometer chip may be packaged as an external module, such as for example a PCMCI card or external module with a USB or Firewire connector, that can be plugged into an auditory stimulator device to permit it to also (or alternatively) function as an audiometer. User input to indicate perception of a test sound may be provided by pressing one or more control buttons on the input key pad (e.g., key pad 1308 in
As a further alternative configuration of this embodiment, the audiometer function may be accomplished by an audiometer software module capable of running on the microprocessor in the auditory stimulator device, where the audiometer software module instructions cause the microprocessor to direct or control digital signal processors in the device to perform the functions of an audiometer chip. Digital signal processors may be employed in the device for generating the stimulation therapy, such as in the digital sound playback chip 1302 illustrated in
In addition to incorporating the audiometer function into the auditory stimulator, additional functionality may be implemented by software to enable the device to calculate a personalized auditory stimulation treatment based upon the results of the hearing level testing. Operating such software, the microprocessor would perform suitable algorithms on test results data stored in memory to produce the appropriate stimulus signals, and then store those signals for use during treatments.
Combining the audiometer function into the auditory stimulator device enables several benefits to clinicians and users. A combined device would eliminate the need for expensive and bulky audiometers, enabling a clinician to offer less expensive services or treat individuals in their home or in remote locations. A combined device may also permit more accurate treatments since the same electronics and transducers are used to test hearing thresholds and to provide stimulation therapies. A combined device would permit individuals to monitor their own hearing levels, track improvements in their hearing, and otherwise participate in their treatment. A combined device would permit connecting clinicians to their patients via electronic networks, such as the Internet, an intranet or a wireless fidelity (WiFi) network, since the patient's device contains both the testing and treatment equipment, and it may configured to communicate test results and other parameters to the clinician via the network (e.g., by communicating with a computer connected to the Internet). A combined device may also permit detection and treatment of hearing loss without the participation of a trained clinician, such as may be appropriate in remote areas and lesser-developed countries.
A block diagram of a combined audiometer/auditory stimulator device is illustrated in
An illustration of an embodiment of a combined audiometer/auditory stimulator device is provided in
In operation, a user of a combined audiometer/auditory stimulator device 1300, 1400 may activate the audiometer function by selecting an option via the key pad 1308, 1402. In response, a script may be presented on the display 1309, 1403 providing the user with instructions for conducting the test. This may involve placing the vibrator, such as piezo transducer 1306, headphones 1412 or a fluid filled neck ring (not shown), on the user's head or neck, and initiating the test by pressing an appropriate button. During the test, the user listens for tones and presses an appropriate key pad button 1308, 1402 whenever a tone is perceived. Software within the device varies the volume presented for each tone and for each ear until the user has provided threshold hearing indications for all test tones. At this point, the results may be displayed, such as in numerical or graphical form, on the display 1309, 1403. Test results may be communicated to a clinician, such as via a communication link 1413 connected to a suitable communication device, such as a personal computer connected to the Internet. The clinician may then determine a suitable, personalized treatment stimulus and communicate it to the device, such as via the communication link 1413, for storage in a memory chip 1406 or digital sound storage card 1301. Alternatively, the microprocessor 1307, 1408 may perform an algorithm to generate suitable, personalized treatment stimulus and store it in a memory chip 1406 or digital sound storage card 1301. Having completed the hearing level test, the user may then operate the device to provide auditory stimulation as described above.
An integrated audiometer/auditory stimulator device may also incorporate additional features and functions to provide effective treatment. For example, the device may incorporate circuitry to permit it to self calibrate, thereby ensuring that the test and treatment signals are provided at the proper frequencies and volumes. A self calibration circuitry may comprise an oscillator circuit that produces a known acceleration output or force level positioned within the device and switched on to check the calibration of the transducer. A visual display and an output adjustment circuit or user input may also be provided as part of the calibration circuit and functionality. As another example, an auditory stimulator device may also be used for entertainment, such as to play music, when treatment is not being applied.
The foregoing description of various embodiments of the invention has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed, and modifications and variations are possible in light of the above teachings or may be acquired from practice of the invention. The embodiments were chosen and described in order to explain the principles of the invention and its practical application to enable one skilled in the art to utilize the invention in various embodiments and with various modifications as are suited to the particular use contemplated.
This application claims priority to U.S. Provisional Application No. 60/536,987 filed Jan. 20, 2004, the contents of which is incorporated herein by reference in its entirety.
| Number | Date | Country | |
|---|---|---|---|
| 60536987 | Jan 2004 | US |
