WO2002042986A1

WO2002042986A1 - Method and system for the diagnostics and rehabilitation of tinnitus patients

Info

Publication number: WO2002042986A1
Application number: PCT/PL2000/000085
Authority: WO
Inventors: Andrzej Czyzewski; Henryk Skarzynski; Bozena Kostek-Czyzewska
Original assignee: Andrzej Czyzewski; Henryk Skarzynski; Kostek Czyzewska Bozena
Priority date: 2000-11-24
Filing date: 2000-11-24
Publication date: 2002-05-30
Also published as: AU2001214231A1

Abstract

The invention provides a method for developing a new type of interactive information, diagnostic and rehabilitation services for people suffering from noise in the ear (tinnitus) and excessive sensitivity to sound (hyperacusis). The new type of service uses the possibilities offered by state-of-the-art computer technology and telecommunications. In particular, a multimedia computer software using the concept covered by the invention, installed locally or on a network computer, makes screening tests of ear noise possible. It uses an electronic questionnaire and presents examples of sounds that resemble ear noise to the subject. Thanks to its unique method of fitting masking sounds to the patient's needs, tinnitus patients can be rehabilitated using the masking or habituation method. The sounds selected to combat the patient's ear noise can be played back according to a shedule set up by the computer programme or downloaded into a miniaturised sound file player with earphones, worn by the patient. Alternatively, the sounds can be in the form of the high frequency dither noise generated in an external ultrasound generator and transmitted to the patient's ear using a miniature vibrational ultrasound probe.

Description

Method and System for the Diagnostics and Rehabilitation of Tinnitus Patients

Background of the invention

The invention is an electronic diagnostic and rehabilitation system for people suffering from internal ear noise, i.e. tinnitus patients and people with an abnormally high hearing sensitivity, i.e. hyperacusis patients.

The problem and the methods for improving the situation of patients suffering from this kind of disorder are known from rich literature and some patent descriptions. Generally, the idea is to deliver external noise to the ear affected with tinnitus in order to mask the internal noise or to habituate patients to their subjectively perceived noise. These topics are extensively covered in the literature, e.g.:

- J. Tonndorf, "The Origin of Tinnitus", Tinnitus: Diagnosis/Treatment, Abraham Shulman Ed. 1991 pp. 41-49.

- J. A. Nernon, "Common Errors in the Use of Masking for Relief of Tinnitus", Tinnitus: Diagnosis/Treatment, Abraham Shulman Ed. 1991, pp. 50-66.

- A. Shulman, "Instrumentation", Tinnitus: Diagnosis/Treatment, Abraham Shulman Ed.1991, pp. 503-513.

- Ch. S. Watson, et al., "Committee on Hearing, Bioacoustics, and Biomechanics- Tinnitus, Facts, Theories, and Treatments", U.S. Department of Commerce, National Technical Information Service, Nov. 1982.

- H. Skarzynski Ed. "Tinnitus and Hyperacusis" (in Polish), Institute of Physiology and Pathology of Hearing, Warsaw, 1998

- H. Skarzynski Ed. "About Tinnitus in Everyday Life" (in Polish), Institute of Physiology and Pathology of Hearing, Warsaw,2000

The earliest US patent No. 4,034,741 dated 1977, presents a noise generator and transmitter employing a circuit that can be switched to provide a variable waveform from an active noise source out of an integrated circuit amplifier. The invention provides a device for improving the aforesaid application in assisting the induction of natural sleep. The proposed solution is rather technologically outdated.

A newer design of a tinnitus masker is provided by the US patent No. 4,222,393, wherein a tinnitus patient is subjected to external sounds of different pitch, one after another, to enable the patient to identify the particular external sound having the same pitch as the subjective tinnitus sound perceived by the patient. Then the patient is provided with a power operated sound generator producing a range of frequencies extending above and below the perceived pitch to mask the tinnitus sound. The sound generator may be worn in the same manner as a hearing aid and may be combined with a hearing aid, if necessary. The primary energy of the sound generator is produced between the frequencies of 1000 Hz, 5000 Hz and 10000 Hz. Some ideas in this patent seem valid such as the concept of matching the shape of the masking sound spectrum to the patients' needs. The proposed electronic design, however, based mostly on discrete elements is technologically outdated. A tinnitus masking device is also described in the European Patent No. 449 860 Bl comprising an electronic circuit for the generation of a sound spectrum which can mask the patient's tinnitus, designed in such a manner that the spectrum generated by the receiver contains a line spectrum of the basic tone, where the frequency of the basic tone is adjustable by the patient. The solution proposed in this patent is much too simplistic to be considered universal for all tinnitus patients.

The PCT Application WO 90/07251 discloses a tinnitus masking device having an electronic circuit arranged in a housing and an earphone for generating a sound spectrum that can mask the patient's tinnitus. It comes with a volume control for setting the sound intensity. In this device, the electronic circuit is designed in a such a way that the sound spectrum generated by the earphone contains a line spectrum with a fundamental tone while the frequency of the fundamental tone can be set by the user. A disadvantage of known tinnitus instruments is that the frequency range and the level of the masking noise cannot be set with sufficient flexibility.

The relatively new US patent No. 5,403,262 defines a tinnitus masking device and method for producing a masking signal with a selected centre frequency, selected bandwidth, and selected volume provided. A random noise generator and a clock circuit are employed in conjunction with a switched capacitance filter bank to produce a masking signal with the selected centre frequency and selected bandwidth. The masking signal is then received by a volume control unit and then amplified for delivery to the tinnitus sufferer's ear or ears by speakers or headphones. Additionally, the tinnitus masking device may include a timer and fade out unit. This solution is relatively close to the present invention, however, since the signal is still produced with a pseudo-random noise generator, it does not have the capacity to use sounds other than noisy sounds which in some cases could effectively mask tinnitus. Moreover, the described system does not perform tinnitus diagnostics.

The next US patent application which covers the related subjects is the US patent No. 5,788,656 which is an electronic stimulation system for treating patients suffering from a tinnitus disorder in which the patient hears ringing or other sounds originating in the ear. The system includes an electronically actuated probe to which a complex signal in the auditory range is applied to cause the probe to vibrate in accordance with the signal. The probe is placed on the patient in proximity of the cochlea of the inner ear. The probe vibrations are transmitted to the cochlea to stimulate this organ and thereby alleviate the tinnitus disorder. In this system, use is made of two adjustable audio-frequency oscillators, one operating in a low frequency range whose upper limit is about 400 Hz, the other operating in a high- frequency whose upper limit is about 1000 Hz. The outputs of these oscillators are combined and amplified to produce a complex signal applied to the probe. The mechanical vibrations transmitted by the probe in accordance with the complex signal must be properly related to the sonic frequencies of the tinnitus sounds being heard by the patient. This patent differs mainly from earlier patents in the way acoustic signals are delivered to the patients' ears which is based on the above mentioned vibrating probes. Similarly, the vibrating direct drive hearing device described in the US patent No. 5,795,287 stimulates hearing by vibrating the structure to which it is coupled. The user may select the frequency, intensity and phase of the tone generated. Additionally, a second tone or a background sound may be selected. Another vibrating device for diagnosing and treating hearing disorders including a supersonic transducer which has a resonance frequency in the supersonic range is described in the US patent application No. 6,068,590. The methods of stimulation proposed in the cited patents are not directly related to the present invention which uses a different concept of acoustic therapy of tinnitus.

The European Patent No. 9611047 concerning the problem of tinnitus has a priority date of 1996 while its American version dated April 2000 bears the number of 6,047,074. It defines a programmable hearing aid that can be used in a tinnitus therapy mode and correct other hearing impairments of the hearing aid user. For this purpose, the hearing aid contains a signal processing chain, between the hearing aid input and output, which is responsible for producing a useful signal by modifying the input signal in order to correct the hearing impairment of the hearing aid user. The signal processing chain also includes an arrangement for generating a tinnitus therapy signal, which is combined in the signal processing chain with the useful signal, depending on the selected or pre-set mode of operation. The tone of the patient's tinnitus can be exactly identified and the corresponding frequency can be covered with a narrow band noise. It is also possible to select a signal by generating melodic sound sequences or other tones to mask the tinnitus which eliminates the limitation of the generated noise. This patent is relatively closest to the present invention, because in the description of the preferred embodiments it says that the masking signals can be generated outside the hearing aid and can be made available to the patient in an arbitrary processed form for tinnitus therapy. However, it does not define any ways of making co-ordinated tinnitus diagnosis neither does it provide a description of the mentioned externally delivered masking sounds. It leaves out the problem of fitting masking sounds to patients and gives no information about the means of recording, shaping and transmitting external signals to the hearing aid in its role as a tinnitus masking device.

Disclosure of the Invention

The invention provides a method for developing a new type of interactive information, diagnostic and rehabilitation services for people suffering from noise in the ear (tinnitus) and excessive sensitivity to sound (hyperacusis). The new type of service uses the possibilities offered by state-of-the-art computer technology and telecommunications. In particular, a multimedia computer software using the concept covered by the invention, installed locally or on a network computer, makes screening tests of ear noise possible. Thanks to its unique method of fitting masking sounds to the patient's needs, tinnitus patients can be rehabilitated using the masking or habituation method. The system can easily deliver information to tinnitus patients, as well.

The system in the invention is explained using figures and an explanation, provided in detail in the next section. The essence of the system lies in the fact that it enables automatic diagnostic examination. In the course of the examination the patient is asked to complete an on-screen questionnaire and hear out a set of sounds whose tone resembles the typical noises subjectively perceived by the patients. The subject is asked to answer detailed questions in the electronic questionnaire and next to identify those sounds which most strongly resemble those they perceive as ear noise. Following an algorithm analysis of the results and analysis of the selection of sounds made by the patient, the computer diagnoses the patient as free from ear noise or classifies them into a risk group. Next, the patient is informed about the result and can then read about the causes of the ailment and the recommended treatment. At this stage, contacting a specialist is advisable. This can be done in person or using the medium of teleconference which can be arranged thanks to the computer system. To facilitate any further contact with the doctor, the system in the invention, upon diagnosing the patient can assign them a Personal Identification Number. Coupled with the diagnostic tool is also a rehabilitation tool which is a programmable ear noise masker. To use it, the patient can try out various masking sounds played back by the system from a sound card through the attached earphones and then download those sounds to a miniaturised personal digital player for further use during therapy. In this way, the system in the invention uses the modern multimedia computer to effectively provide information about the ear noise and diagnose the problem. It also suggests a therapy which uses optimised ear noise masking provided externally using a filtered noise or synthetic sounds or natural sounds.

Detailed Description of the Invention

The system in the invention can be used on a typical multimedia personal computer equipped with a sound card, earphones and a communication port for sending sound samples to miniaturised digital recorders. The software for diagnostics and rehabilitation of ear noise can be installed on a local or network computer with which the user's computer will communicate. In the second case, the system in the invention can be implemented as mass use service, e.g. by making it available on the Internet.

The electronic questionnaire used in the diagnostic and rehabilitation system in the invention can consist of about 10-30 questions elaborated by specialists. The questions can be about the results of hearing tests, genetic background, hearing disease record, dizziness, duration and frequency of the ear noise, exposure to noise in everyday life, consumption of stimulants, arterial hypertension, etc. The sound material used for a comparative examination of the nature of the ear noise subjectively perceived by the patient can include sound files, with band filtered white noise, simple tones of various frequencies, multi-tones, both harmonic and non-harmonic and different types of synthetic and natural sounds which resemble e.g. low frequency thumps, murmur, rustle, twitter of birds, sounds made by the cicada, dripping of water, whistling and many others. The preferred number of sounds to which the subject should be exposed for further comparison with the ear noise they hear, ranges between 10 to 20. The results of the questionnaire are analysed in an algorithmic analysis followed by an analysis of the selection of sounds made by the patient. Based on these, the computer diagnoses the subject as free from ear noise or classifies them into a risk group. The decision-making algorithm can use expert knowledge on ear noise diagnostics which gives it the deterministic function. It can also be a learning algorithm, like a neural network for example, which learns to make automatic diagnoses after it has been trained on sets of data obtained from a sufficiently large group of patients.

Alternatively, in the case of using the known method of tinnitus therapy where the patient is habituated, the computer system in the invention can have a software which supports the treatment through a programmable training of the patient's hearing controlled by the computer. In this case, the role of the computer system in the invention is to save in its memory the schedule of playback sessions, types of sounds to be played back by the patient and the level of their loudness. The computer programme can be set to not only store the recommendations as to the frequency and duration of the training but can also automatically remind the patient that they have to begin training. The training sounds can either be played back from the computer or sent to the miniature sound file player.

Alternatively, the patient's ear can be exposed to ultrasounds which are signals of frequencies that are inaudible to the human ear. In this case, an ultrasound generator can be used which can receive its settings from the computer through an interface, in particular a serial interface operating in the USB standard or through an infrared communication port. The role of the miniature ultrasound generator is to generate noise or tonal signals whose energy is typically concentrated between 20 kHz to 100 kHz or even higher. A miniature ultrasound probe is connected to the output of the ultrasound generator. The probe is placed inside the patient's ear canal, preferably in a position that enables the propagation of the acoustic wave through the tissue near the middle ear. The authors of the invention have observed that the problem of ear noise masking is analogous to the problem of reducing the noise made by the analogue-to-digital converter in the range of low signals and the so called digital deafness. These phenomena are known in digital signal acquisition. They originate when signals on the input of a digital channel are particularly low. As a result, in the digital input circuits self originating internal noises occur, of varying nature, which resemble certain cases of tinnitus. Because of this, in digital acquisition technology and signal conversion a method was developed to minimise those spontaneous noises and interference by adding to the input small amounts of extra noise, called dither noise. Dither noise linearises the threshold characteristics of the analogue-to-digital converter's sensitivity. As a result, the parasitic noise, originating inside the channel, is reduced. Recently, noise or a high frequency signal are used more and more often as the dither noise. To continue the analogy which in the case of hearing is caused by a raised auditory threshold resulting from inner ear diseases, one can draw the conclusion that the increased threshold level of auditory cells responses or excessive sensitivity to sounds can become the reason for a subjective perception of noises originating inside the patient's auditory system. The noises originate similarly to how noises originate in the digital audio channel. Combating the effects of the phenomenon is similar in that the dither technique can be used in which the spontaneous noise is masked by a noise or signal, especially a high frequency one, fed externally. For this reason, in the system in the invention it is postulated that a noise or signal whose spectrum is within the ultrasound frequencies be used as tinnitus masker acting as the dither noise.

Sounds from the audio band that the patient (preferably after additional consultation with a specialist) will select for use in everyday life as maskers or in habituation therapy, in the system in the invention can be downloaded from the computer to a digital sound file player, equipped with miniature earphones. It is important to note though, that patients who complain of ear noise should not have their ears blocked. Therefore, open earphones should be used. The basic advantage of this method of sound generation is that the sounds can be used directly and can be coded in the mp3 format. A modern digital player is very small, light weight, battery powered, has no rotating mechanical elements of the medium which makes it a very convenient portable tool for playing back a fitted tinnitus masker.

A block diagram of the system for fitting masking signals and how they are generated for therapy is given in Fig. 1. The acoustic signal fitted to mask the ear noise of the patient or recommended for habituation purposes is sent from the computer 1 through its sound signal input 2 to earphones 3 or to the ultrasound probe 7 or through a serial interface 4 is then downloaded to the miniature sound file player 5 which can come as a stand alone file player in the mp3 format or as mobile phone acting as player or a watch that can perform this function. The sound level can be adjusted in the computer 1 in the programme or in the device 5 using a gain control 6 to match the patient's needs. The computer 1 uses the software to diagnose and rehabilitate ear noise which is installed on a local or network computer with which the local computer is connected via a computer network. In the case, when the signal being sent to the patient's ears is a high frequency dither noise, the device 5 assumes the role of a programmable ultrasound generator whose settings can be sent from the computer 1 through the serial interface 4 and delivered near the tympanic membrane of the patient's ear through a miniaturised vibrational ultrasound probe 7.

Today, more and more people use mobile phones. Some models of mobile telephones have built-in sound file players. In this way, the audio background can be played back as is the case in the mp3 player, mentioned earlier. This solution minimises the costs and there is no need to carry a separate device. The earphones can also be used for talking on the phone. It can be connected to the computer using the USB interface's cable or another serial interface, e.g. an infrared port.

In addition to that, there are also electronic watches with a built-in sound file player. The quality of the player is just as good as that of other sound file players. The watches usually come with a cable to connect to the computer and special software for sending the files to the watch. The devices for tinnitus therapy can also be made using the design of the invention.

Brief description of the drawing

Fig. 1 presents a block diagram of the computer system used in tinnitus therapy.

Claims

1. Method for tinnitus diagnostic screening based on an electronic questionnaire, said method consisting of a set of questions and sounds imitating ear noise to enable the classification of the patient to one of the tinnitus risk groups on the basis of automatic analysis of the results of the questionnaire and the selection of the tinnitus sound pattern.

2. Method as given in claim 1, in which an automatic tinnitus diagnostics is made on the basis of a deterministic decision-making algorithm developed by tinnitus specialists or on the basis of algorithms which learn on the data sets obtained from a large group of patients including in particular artificial neural network based algorithms.

3. Computer system for tinnitus screening and rehabilitation, the system containing a locally or remotely installed software with the option to program an auditory training conducted using the habituation method by determining the frequency and level of loudness and duration of the particular sounds to be played back by the patient including the option to automatically alert the patient to the need to begin training.

4. System as given in claim 3, in which the sounds selected for the therapy can be played back from the computer through the earphones using the computer's audio output or downloaded through a transmission port to a miniature digital player which is a stand alone device or built into a mobile phone or an electronic watch and then directly used to play back the sounds with the loudness adjusted to the patient's needs.

5. System as given in claim 3, wherein the masking signal is a noise or signal whose energy is concentrated in the ultrasound frequencies used as dither noise generated in a miniature ultrasound generator worn by the patient which are then transmitted to the patient's ears using a miniature probe which is a vibrational ultrasound transducer.