AU2004218727A1 - Tinnitus rehabilitation device and method - Google Patents

Description

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AUSTRALIA

PATENTS ACT 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT

ORIGINAL

Name of Applicant: Actual Inventor: Curtin University of Technology Paul Benjamin Davis Address for Service is: SHELSTON IP Margaret Street SYDNEY NSW 2000 CCN: 3710000352 Attorney Code: SW Telephone No: Facsimile No.

(02) 97771111 (02) 9241 4666 Invention Title: TINNITUS REHABILITATION DEVICE AND METHOD Details of Original Application No. 31370/00 dated 17 March 2000 The following statement is a full description of this invention, including the best method of performing it known to us:- File: 35896AUP01 500448863_1.DOC/5844 la-

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TINNITUS REHABILITATION DEVICE METHOD 0O FIELD OF TE INVENTION s The present invention relates to a tinnitus rehabilitation device and method for providing relief and treatment to persons suffering from the disturbing effects of tinnitus and relates particularly, though not exclusively, to such a method and device that employs intermittent masking ofthe tinnitus.

BACKGROUND TO THE INVENTION Tinnitus is the perception of a sound in the absence of any corresponding external sound.

It is most commonly perceived as a ringing, buzzing, whirring type sound, but can also be.

perceived as a beating, or pounding sensation. Around one third of people who suffer from tinnitus can be quite highly disturbed by it. Continuous perception of tinnitus can lead to insomnia, an inability to relax, state and trait anxiety, depression, and even suicide in extreme cases. Often closely associated with tinnitus is the perception of hyperacusis, which is a great intolerance to external sounds, even the softer everyday sounds. This distressing condition can even occur as a precursor to tinnitus, and is thought to share the same underlying causes. Thus, every reference to tinnitus in this document should be construed as including the phenomena of hyperacusis or other types of loudness discomfort.

There are very few effective treatment options available for tinnitus sufferers, with the vast majority only being advised that "you'll have to learn to live with it". Most patients find that they can far more readily ignore an external sound than their tinnitus. One palliative method has been to use hearing aid-style devices that produce a band of noise to totally mask the perception of the tinnitus. This gives a sense of relief and control over the tinnitus in around half of patients, but usually has no long-term effect. The prohibitive cost (around AS1500) and aesthetic considerations limits the proportion of sufferers for whom this is a viable measure. The presence of hearing loss for external sounds in the tinnitus region often means that the masking noise needs to be unpleasantly loud before the tinnitus can be masked, and the noise is often judged to be not much better than the

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S-2tinnitus itself.

In the past four years, a new understanding of the neurophysiological processes underlying 00 tinnitus has been published, emphasising the role of the neural pathways in the emergence C 5 of distressing tinnitus and the possibility of using this neural plasticity to retrain its O perception. This has been dubbed "Tinnitus Retraining Therapy" or TRT. In this technique, patients are given intensive counselling, and use noise generators at a volume that does not completely mask the tinnitus. Long term reductions in tinnitus disturbance have been achieved in some patients, but it is usual for this process to take at least 18 months of therapy before any substantial benefit occurs. TRT also offers very little immediate sense of relief from the tinnitus, and no relief from the associated sleep disturbance and inability to relax.

The closest known prior art to the invention is the "Silentia Set" developed by Starkey Corp. which is a pair of hearing aid devices which wirelessly receive signals from a stereo system via an induction loop under a pillow at bedtime. Recording of high frequency noise bands ("water sounds"), babble noise, traffic sounds and music have been used to mask tinnitus using this system, however the high cost of the Silentia Set make it prohibitive for many sufferers.

Other prior art audiotherapeutic techniques using music are the Tomatis Method developed by Alfred A. Tomatis, and Auditory Integration Training. While neither method is designed for the treatment of tinnitus, the two techniques have some similarities in that they modify music for the treatment of auditory disorders. The Tomatis Method employs an "Electronic.Ear" developed by Alfred Tomatis, (US 4,021,611). It has its origins from an extremely outdated model of how the auditory system works, and has been widely debunked by audiological organisations. Auditory Integration Training is based on the Tomatis Method, but presents the music at extremely loud levels, that may result in hearing damage, and importation of devices using this technique have been banned by the American Food and Drug Administration.

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c' -3- SUMMARY OF THE INVENTION The present invention was developed with a view to providing a more effective S. rehabilitation technique and device for tinnitus suffrers that is consistent with 00 contemporary understandings of the underlying pathology in the auditory system, of C '5 which tinnitus is a symptom.

O Throughout this specification the term "comprising" is used inclusively, in the sense that there may be other features. and/or steps included in the invention not expressly defined or comprehended in the features or steps subsequently defined or described.

What such other features and/or steps may include will be apparent from the specification read as a whole.

According to one aspect of the present invention there is provided a tinnitus rehabilitation method for providing relief to a person suffering from the disturbing effects of tinnitus, the IS method comprising: providing an audio signal spectrally modified in accordance with a predetermined masking algorithm designed to modify the intensity of the audio signal at selected frequencies whereby, in use, when the spectrally modified audio signal is heard by the person it provides significant masking of the tinnitus.

Preferably the method further comprises the steps of: transmitting, using a computer, data representing an audiogram of the person suffering from tinnitus; processing said audiogram data at a remote location and producing required equalisation response data based on said audiogram data using said predetermined masking algorithm; receiving, using a computer, said required equalisation response data; and, combining said required equalisation response data with audio data 3 0 representing said audio signal to produce said spectrally modified audio signal.

According to a second aspect of the invention there is provided a method of using a 0 0 (N -4computer to provide access to a predetermined masking algorithm used in tinnitus rehabilitation, for providing relief to a person suffering from the disturbing effects of tinnitus, the method comprising: 00 receiving on-line, from a user, data representing an audiogram of the person suffering from tinnitus; processing said audiogram data using said predetermined masking algorithm to produce required equalisation response data based on said audiogram data; and, transmitting said required equalisation response data to the user.

According to a another aspect of the present invention there is provided a tinnitus rehabilitation sound recording for providing relief to a person suffering from the disturbing effects oftinnitus, the sound recording comprising: an audio signal spectrally modified in accordance with a predetermined masking algorithm designed to modify the intensity of the audio signal at selected fequencies whereby, in use, when the sound recording is heard by the person it provides significant masking of the tinnitus.

Preferably the predetermined masking algorithm provides intermittent masking of the tinnitus wherein, at a comfortable listening level, during peaks of the audio signal the tinnitus is substantially completely obscured, whereas during troughs the perception of the tinnitus occasionally emerges. In practice it has been found that such intermittent masking can provide an immediate sense of relief, control and relaxation for the person, whilst enabling sufficient perception of the tinnitus for habituation and long term treatment to occur.

Typically said predetermined masking algorithm is designed to modify the intensity of the audio signal across substantially the full spectral range of the audio signal. Preferably said audio signal is a highly dynamic signal in which the spectral content and intensity constantly varies over time. Most preferably the audio signal is a music signal. However other types of signals including speech or noise might also be employed.

Advantageously said predetermined masking algorithm is at least partly tailored to the 0C) audiometric configuration of the person. Typicall said predetermined mnasking algorithm Cl 5 is partly tailored to the hearing loss characteristic of the per Preferably the spectral qualities of the audio signal ar odified by the masking algorithm so as to provide a relatively equal sensation level across a major portion of the audio spectum in both ears.

Typically said p~redetermnined masking, algorithm.- also incorporates a set of calibration figures such as for converting dB HL (Hearing Level) to dB SPL (Sound Pressure Level).

or to correct for the presence of various coupling system types.

According to a still fiurther aspect of the present invention there is provided a tinnitus rehabilitation device for providing relief to a person suffering from the ditubing effects of tinnitus the device comprising signal filtering means adapted to spectrally modify an audio signal in accordance with a predetermined masking algorithm designed to modify the intensity of the audio signal at select ed fi-equencies whereby, in use, when the spectrally modified audio signal is hearc~byithe persn-it provides significant masking of the tinnitus.

Pieferably said signal filtering means is a programmable signal filtering means wherby, in use, the device can be programmed with a predetermined masking algorithm adapted to the particular needs of the individual suffering from innitus.

In a preferred embodiment of the device the predetermined masking algorithm is of the form; REQ M(SPL ELC (01.-5.1S,2,3,4.6,8.10.12 kHz) Baseline) where REQ Required equalisation response of the Thinitus Retraining Protocol Baseline= 0.5 B A mean dB SPL at the two adjacent greatest hearing loss frequencies

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5 ELC transfer values for 40 Phon Equal oudness Contours M gain multiplier 0.3 to 0.95 0 Preferably M 0.4 However, in an alernative software embodiment. of the invention, the mathematical algorithm by which the individual prescription of the audio signal is calculated may differ from the above algorithm. Such other embodiments of the invention would be consistent with the essential clinical technique that is intended to provide a modification of the intensity of an audio signal to account for hearing levels specifically for the relief and/or 5 treatment of tinitus ain th gratst haring loss ard hypeis.

Preferably the device is employed in conjunction with a personal music player (PP) and has an input adapted to connect to the audio outpjacent easthone jack on the Pqu es Preferably the devicedlasia-standard-headphone jack to which a standard PMP headphone can be connected. Altemately, a transmitter may be used to transmit a signal to a wireless type of receiver that may be placed in the ear canal, concha aea, behind'the ear, or some Sother a rehlae least hearing loss ear BRIEF DESCRIPTION OF THE DRAWINGS SIn order to facilitate a r ding threshos m dBthe nature of the invention preferred 5 ELC transfer values for 40 Phon Equal Loudness Contours 0 M gain multiplier 0.3 to 0.95 Preferably M 0.4 0 However, in an alternative soware embodiment of the invenrehabilitation device and ethd will now be described in algorithm by wchay of exathe individual pwith rescriptin of the audio signal is calculated may differdrawing in which: fromigure is above graphical representatiuch other embodiments of the invention would e consistent with0 and a typical prior art tia clinical technique that is intmaskerded to provid a modification of the intensity of an audio signal to account for hearing levels specifically for the relief and/or freatment of tinnitus and hyperacusis.

Preferably the device is employed in conjunction with a personal music player (PMP) and has an input adapted to connect to the audio output headphone jack on the PMP.

Preferably the device'hasa-'standard-headphone jack to which a standard PMP headphone can be connected. Alternately, a transmitter may be used to transmit a signal to a wireless type of receiver that may be placed in the ear canal, concha area, behind' the ear, or some other area relatively dose to the ear.

BRIEF DESCRIPTION OF THE DRAWINGS 2 5 In order to facilitate a more detailed understanding of the nature of the invention preferred embodiments of the tinnitus rehabilitation device and method will now be described in detail, by way of example only, with reference to the accompanying drawing in which: Figure 1 is a graphical representation of the long-term spectra of both a music recording and a typical prior art tinnitus masker, Figure 2 is a graphical representation of a typical patient's hearing thresholds and their

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required equalisation curve calculated using a first embodiment of the masking algorithm; C Figure 3 is a schematic diagram graphically illustrating intermittent tinnitus masking with 00 music; cN Figure 4 is a graphical representation of the same patient's hearing thresholds and their Srequired equalisation curves calculated using a second embodiment of the masking algorithm; Figure 5 is a schematic block diagram of a possible embodiment of a tinnitus rehabilitation device in accordance with the invention; and Figures 6 and 7 are flowcharts illustrating a preferred method of providing a tinnitus rehabilitation sound recording in accordance with the present invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS Tmnitus masking can be broadly defined as the obscuring of tinnitus perception with an external sound. Hearing aids can provide an effective form of environmental nois masking for only. around .1 S0 of suffeeres. The most reliable audiometric measure of the effectiveness of tinnitus maskers is the amount of noise required to just.mask an individual's tinnitus. This measure is known as the Minimum Masking Level Amongst the most important criteria for successful masking is that the acceptability of a masking stimulus is inversely proportional to its MML, and that the stimulus needs to be a sufficiently pleasant substitute for the tinnitus. In the present inventor's clinical practice, several sufferers have reported attempting to use music to find relief from their tinnitus, but often found that the volume required to mask their tinnitus was unacceptably high.

Most of these persons tended to have a steeply sloping hearing loss characteristic, and a tinnitus pitch which closely corresponded with the edge of the maximal hearing loss frequencies. One of the reasons why previous attempts at using music have not always been successful may be the extremely high co-morbidity of high frequency hearing loss with tinnitus.

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c -8- Typically, the presence of a sloping high frequency hearing loss would mean that at a relaxing sound volume level, only the low pitch components of the music are heard, and therefore the perception of any musicality and high frequency available for masking is 00 inhibited. The long term spectra of both a music recording and a typical prior art tinnitus masker (a Starkey TMS) are illustrated in Figure 1. A sound level analyser was used to average the response of each of the two recordings over a 64 second period. The spectra were then matched at I kHz to enable a comparison of the frequency composition of the two spectra, irrespective of overall soundpressure-levels. As can be seen from Figure 1, if the masker is assumed to be the optimal frequency response for hearing impaired listeners, then the unfiltered music has insufficient high frequency energy and excessive low frequency response. Therefore, the present inventor has developed a tinnitus masking protocol which modifies the frequency response characteristics of an audio signal with a view to overcoming some of the shortcomings of traditional tinnitus maskers.

Although the following description will be made primarily with reference to modifying the frequency response characteristics of music, it is to be understood that a tinnitus masking protocol in accordance with the invention may also be applied to other types of audio signal suitable for masking of tinnitus, or for providing auditory stimulation for tinnitus and hyperusis-therapywithout-masking.:Furthermore, in view of the relatively high cost of traditional hearing aid-style maskers, the following description will give particular emphasis to the use of conventional, insert or wireless headphone systems or insert type headphones in conjunction with a suitable personal sound reproduction system such as a high fidelity personal music player (PMP) for audio cassette, CD or MP3 recordings. In Australia, the retail cost of a high fidelity PMP is around one-tenth the cost of conventional binaural maskers. However, it is to be understood that the tinnitus masking protocol according to the invention may also be applicable to conventional hearing aid-style maskers. The technique can also be applicable to the setting of additional user programs in hearing aids, or the modified signal may be transmitted to the tinnitus sufferer through their hearing aids' telecoil or induction coil facility.

In addition to the low cost and high portability of PMPs, they generally possess small headphones with long-throw transducers thai enable far superior fidelity compared to most

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free field loudspeaker systems. Furthermore, headphones are generally more effective than loud speakers because they circumvent the extensive attenuation of high frequency sounds that occ urs through a free field. Changes in PM? earphone position on the pinna 00 have been shown to have very limited effects on the spectral composition of toned sweeps measured in a KEMAR (Knowles Electronic Mannequin for Acoustic Rzsearcb).

CI In developing a tininitus masking protocol, the required extended tipper frequency stimulus presented challehies -for. the conversion of audiograin results to the required real ear response, given that there are as yet no internationally agreed-upon standards for the conversion between dB HL to dB SPL for 10 and 12 kHz pure tone and narrow band noise stimuli. The manufacturer's calibration specifications for a Madsen OB 82 audiometer were used to extrapolate the required values for use with a telephonics TDH 39 headphones and MX 41/AR cushions. The audiometer was professionally calibrated accordingly. The values for 10 kcHz were 50 dB HL 59.5- dB SL and at 12 kHZ, 50 dB HL =61 dB SPL All ISO hearing level frequencies below 10 kHz were calibrated as per the relevant Australian standards (AS 1591.2 -1987). Table 1 lists the tansfed/calibration values in inverted format used for converting dB HL to d3 SPL Table 1 _____-Frequency kz 0.25 .0.5 11 1.5 2 3- 3 6 8 10' 12* IB 255 1.5 7.0 6.5 9.0 10.5 10-5 16-5 12.0 9.5 11.0 A further feture: of the first tinnitus masking protocol (T7MP I) developed by the inventor.

was an adaptation of the half gain rule, whereby amplification for heating loss is most effective when it compensates for-only around one half of the hearing deficit. Thiis rule underlies most current hearing aid prescriptive practices. TeTMP I attempted to mnaximise the acoustic energy centred around the pitch of the individual's tinnitus, and to "balance" the headphone output to correct for any asymmetrical hearing loss. A further goal was to enable the balanced per-ception of the masking stimulus throughout the person's head, rather than at the ear level like traditional uncos-related tinnitus maskers.

010 All PMPs; have a volume control range that far exceeds what is available in hearing aids, and so the TMIPI did not need to specify absolute gain figures However, PMPs generally OC) do not possess a left/right balance control, and this was expected to reduce their acceptability in cases of asymmetrical hearing loss and its associated loudness recruitmnent.

As the TMPI formulae aimed to minimise the perceptual loudness of the music or noise c-I required to mask an individuals tinnitus, it thus only needed to specify' the relative fr-equency respousei characteristics :forteach. ear.when presented in those reproduction systems that do not provicle individual control of each stereo channel.

The procedure for applying the TMPI was thus as follow.: The individual's- pure tone hearing level thresholds at each fr-equency were convierted to dB; SPL by the addition of the transfer values in Table 1.

Cii) The tinnitus pitch match frequency in the most severely affected ear was chosen for the maximal point of the base line calculation.. The two adjacent best hearing thresholds of te.lesser hearing :loss-ear wasalways chosen as the minimum point of the calculation. When a reliable pitch match was not found using pure tones, it was substitfted with the mean of the two adjacent best hearing firequencies. Thus, the base line constituted a mnid line value between the two greatest audiometric extremities.

iii) TIhe final equalisation values were then derived by subtracting the base line from the hearing threshold (expressed in diB SPE.) for each fr-equency and each ear. Thus the algorithm for patients whose tini'itus pitch could not be reliably determined was: Baseline 0 B Required Equalisation, REQ 0-5 SfaAI ,2O2- Baseline) The algorithm for non-tonal tinnitus was: Baseline

B

REQ =0.5 {SPL(0zoJ;5W.4 6 IlG0,1 Baseline) c-I Wherein, 0C) A =heating threshold (dB SPL) at frequency of tinnitus pitch match.

B =mean dB SPL at th2adjacent lasthearing loss fequencics.

C- mean dB SPL at the 2 adjacent greatest hearing loss frequencies.

Example I Figure 2 is a graphical representation of the relationship between a typical individual's hearing levels, tinnitus and their required ThlI equalisation curves. This individual has a steeply sloping high frequency bilateral hearing loss and tinitus at 10,000 Hz, both greater on the left side. Consequently, the required equalisation curves revolve around the equaliser's baseline, achieving a partial correction for hearing loss by boosting the amount Of high frequency gain and also correspondingly attenuating the low frequencies. As the IS hearing loss and tinnitus is worse on the lekt that ear receives correspondingly greater amplification. Because of the abnormnal growth of loudness perception which usually accompanies sensorineural hearing loss, (recruitment, and/o .r the presence of hyperacusis), complete correction for hearing levels is not provided, as this may exceed the individual's loudnes discomfort levels.

A tinnitus rehabilitition sound recording was then produced on an audio cassette tape for use in the individual's PMP. A stereo frequency. eqaliser (Genexxa 31-9082) was used in this procedure, which includes ten adjustable frequency bands per channel, with centre frequenicies at 0.031, 0.062. 0.125.0.25,0O.5. li 2.4, 8, 16 kHz. Each control had a range of or 12 dB SPL The equaliser featured an 'EQ record" facility, so that the audio signal could be passed through the equaliser circuit before being recorded. The equaliser's controls for each of the ten fr-equency bands was set to the calculated values for the left ear in the left channel of the equaliser, and the right ear values set in the right channel, in accordance with the particular individual's equalisation values as calculated by the TMP I algorithm. The stereo output from a broadcast quality cassette recorder was connected to the stereographic equaliser, which then had its output routed to another high fidelity cassette deck for recording onto high fidelity audio cassette tape. Dual leads and stereo 1-12- RCA connecters were used to preserve L/R channel separation.

c-- 00 trials with 30 participants. Each participant was counselled as to the rationale behind C 5 masking therapy and the possible benefits of using the tinnitus rehabilitation sound O recording. Each participant was issued with a new PMP with standard insert headphones (Sony MDR E552) that fit into the concha and thus do not require a headband. Sound level-peak analysis-measures were then.performed. With their custom-made tape playing in the PMP, they were asked to slowly turn up the volume until they could just no longer perceive their own tinnitus. This level was marked on the volume control wheel. Each participant was told to notify the audiologist if they subsequently needed to turn up the volume further than the marked position. They were encouraged to experiment downwards with the volume control over the course of each masking session, as they might find that they require progressively less volume to totally mask ifresidual inhibition occured.

One group of participants was given a noise tape whereas the other group was given a music tape. While both treatment groups has similar levels of pre-therapy distress associated with-theiPinnitus,:the-music group displayed a much greater impiovement by mid-therapy and these gains were maintained at the two-year post-therapy follow up. he noise group also displayed some improvement, but much less dramatic then the music group. 96% of the participants found their music or noise tapes to. be an effective masker.

which is a far higher acceptance rate than for conventional earlevel tinnitus maskers In some cases, the TMPI appeared to present an unbalanced perception of loudness where the individual possssed a substantial inter-aural asymmnetry. The real-car perception of loudness may have deviated from the prescribed response due to perception of loudness differences at various points across the frequency range. It was also thought that the half gain rule for hearing aids might be best suited. for the moderate hearing loss population,: and that a mild hearing loss might only require one-thind gain. Furthermore, it is possible that the recruitment of loudness phenomena might be greater in tinnitus patients than nontinnitus patients, particularly given its high co-morbidity with hyperacusis and

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S-13phonophobia (the fear of external sounds). These factors suggested that the TMPI might be over-compensating for hearing loss, and that further modifications were required to optimise the procedure.

00 S The main purpose of the TMPI algorithm was to produce an acceptable substitute for the tinnitus at the lowest possible MML and to accommodate for any intemraual symmetries.

C- However, it was subsequently realised that an improved masking algorithm would be more robust if the prescription of the requirdd equalisation response was performed solely on the basis of maximum and minimum hearing levels, and thereby attempt -to provide relatively equal sensation levels at all frequencies. Data from the TMPI study indicated that 44.4% of the music group, and 28.6% of the noise group participants preferred to set the volume of their audio tapes at a level which only partially masked their tinnitus. This occurred despite being instructed that the optimal setting was to totally mask. The differences in masking level preferences between the two types of stimuli also suggests that music was more acceptabl than noise when used at volume levels where the tinnitus could still be partly perceived. Whilst the historical approach has been to totally mask tinnitus, and the current clinical trend is to partially mask, the present inventor has developed an improved tinnitus masking protocol based on intermnnittent masking. Since music is a highly -dynamic.signal,.it-appears possible that the intensity of music which partially masks might actually constitute a form of intermittent masking. A schematic representation of intermittent tinnitus masking using a music signal is illustrated in Figure 3.

Without wishing to be bound by theory, it is believed that the intermittent masking of tinnitus with a relaxing stimulus (such as music) may be effective on a psychological, as well as on an acoustic or neural level. In theory, it is feasible that intermittent tinnitus masking with music might constitute a form of systematic desensitisation. Whilst in a relaxed state, the listener might be alternatively perceiving, then not perceiving the tinnitus, according to the fluctuations in the peak levels of the music. The predicability of the music may mean that the tinnitus might not even be consciously perceived during the "troughs" of the music. Additionally, the tinnitus might "reappear" from the music often enough for habituation to occur. But the ongoing dynamic nature of the music signal -14prevents this limited exposure from being disturbing, and this may reduce any limbic system enhancement. Thus, the proposed intemnittent-masking-with-raxation-music C' technique may promote a synergetic effect through its additional mechanisms of Q facilitating a sense of control, a reduction in general anxiety levels, and a form of autohypnosis leading to a reduction of fear about the tinnitus itself Therefore, an improved masking algorithm based on a tinnitus retraining protocol (TRP) was developed that was designed to produce intermittent masking of the tinnitus.

In practice, the TMPI algorithm's use of the half-gain rule appeared to over-compensate for hearing loss as noted above, sometimes making the recording seem unbalanced or "tinny". Conversely, there were several factors that suggested that the one-third rule might not provide sufficient equalisation. The long term music spectrum has considerably less high frequency energy than what is typically available from conventional tinnitus maskers, and yet the greatest hearing loss is typically concentrated in this region (see Figure 1).

Therefore, any substantial reduction of gain could prevent achieving adequate high frequency equalisation to overcome the limitations in the music spectra and the effects of hearing loss. Therefore, because the half gain rule was sometimes excessive, but one third gain may be insufficient for the purposes of modifying music for long term tinnitus retraining, a mediumwas selectedbythe-incorporation ofa 0.4 gain multiplier, To further facilitate the provision of equal sensation levels of music across the full spectral range of the music signal, the improved TRP algorithm adopted the ISO Equal Loudness Contours (ELC. The ELC transfervalues correct for any differences in loudness perception depending on the discreet frequencies (International Standards Association, 1961). The 40 phon contour curve was selected because the earlier study found that the mean participant's customised music recordings, under total masking conditions, displayed a RMS of 45.7 dB SPL. Thus, with g dB representing an approximate doubling of perceived loudness, 37.7 dB was extrapolated to be the midpoint between the threshold and total masking, and thus representative of the intensity around which intermittent masking would occur with those with a mild to moderate sloping hearing loss. The phon contour was thus utilised becuse it was the closest to this mid point, and choice of the lower value curve also helped compensate for loudness recruitment.

The standard audiometric procedure is. to obtain- hearing thresholds using TDH 39 headphones, and the results are expressed in dB HlL (Heaing Level). However, the 0C) convention for specifying hearing aid characteristics is to utilise, dB SPL (Sound Pressure CI 5 Level) values. Consequently the hearing thresholds (dB HlL) obtained in the 6cm 3 headphones need to be converted into dB SPL by the addition of the transfer values in Table 1.

These transfer values wre then summnated wth the 40 Plum contour values. The resulting transferfealibration values are displayed in Table 2.

Table 2 Frequency kd-z .25 .5 1.75 1 1-5 j2 j 4 6 8 10 1 Corretion 235 75 5.57 6.5 7 5.5 25 16.5 121 1 1.

The tinnitus retmainingprotoctd (TRP-gorithnis:a modification of the TMPI algorithm given on page 10 above, and is as follows: REQ 0.4 {ELC S?1 A10..Ijt Baseline) Wbere: Baseline 0.5 B A mean dB SPL at the two adjacent greatest hearing loss frequencies in the greatest hearing loss ear.

8= Mean 0B SPL at the two adjacent least hearing loss frequencies in the least hearing loss ear.

SPL =hearing thesbolds Cm dB HL). converted to dR SPL.

ELJC =transfer values for 40 Phon Equal Loudness Conitours.

Alternatively, the patient~s hearing thresholds may be obtained using 1/3 octave 'narrow band noises, and the gain multiplier becomes 0.7 (or between the range of 0.5 -16 0.95).

The procedure for applying the flU was as follows: 00 The person's audiogram was perused to ascertain the two adjacent greatest hearing loss frequencies in the greatest hearing loss car and also the two adacent least hearing loss frequencies in the least hearing loss ear i i) These four dB HL values were then converted to dB SPL. by t addition of the transer values inTable I (on page 9).

(iii) The dB SPL mean. of the two adacent greatest hearing loss frequencies in the greatest hearing loss ear was then calculated in dB SPL. and the procedure repeated for the two adacent least hearing loss frequencies in the least hearing loss ear (iv) A midline value was then calculated by the subtraction of B from A, which value is then halved, and the result added to the B value. This is the TRP baseline.

All o~thedBHL thresholdsfrom the audiograM w~ere then added to the values in Table 2 above which is the summation of the ISO 40 Phon ELC correction values, and thie d3 HL to dB SPL transfer functions. This produces a measure of hearing in terms of the relative perceived loudnes of stimuli at each of the discrete fiequencies. The. values were expressed in dB SPL so ftht the. desired equalisation fi-euency response could boe determined w~ithin the 24 dB SPL range of the graphic equaliser.

(vi) The baseline value was then subtracted from each transformed threshold, and its result then multiplied by the 0.4 gain rule. Tlfis process is repeated for each fr-equency of each ear.

(vii) These values were then .used to manually set the graphic equaliser with the left ear's required equalisation. response (RLEQ) used in the left channel, and the right ear's REQ used in the right channel of the equaliser.

Example 2 The audiogramn for the participant chosen to demonstrate how the TMPI accounts for a steeply-sloping asymmnetrical hearing loss (see Example!I above), was also chosen to 00demonstrate how the TRP algorithm modifies the intensty of the audio signal at selected fi-equencies to provide intemittent masking of the tinnitus. Tables 3 and 4 below show the calculations at each fr-equency for the left and right ears respectively using the TRP algorithm above. The baseline calculation was made as follows: Baseline =0.5 B 0-5(L SPLO+L SPL 1 .5(R SPL 0 SPL,,,JxO5+O.5(R SPL 0

SPL.,,

[0.5(89.5 91) 0.5(l.5 8.5)1 x 0.5 +0.5(1.5 (90.25 x 0.5 47.625 -18- Table 3 Corrtians and Calculations LFreq. Ps Ps ELC SPL (Hz) dB HL SPL- tansfer functions x0.4 REQ Baseline 250 5 23.5 28.5 47.625 -19.15 x 0.4 -7.66 500 -10 75 -2.5 471625 -50.15 x 0.4 -20.06 750 2.5 5.5 8 47.625 -39.65 x 0.4 -15.86 1000 15 7 22 47.625 -25.65 x 0.4 -1026 1500 25 6.5 315 47.625 -16.15 x 0.4 -6.46 2000 40 7 47 47.625 -0.65 x 0.4 -0.26 3000 65 5.5 70.5 47.625 22.85 x0.4 9.14 4000 60 2.5 62.5 47.625 14.85 x 0.4 5.94 6000 60 16.5 76.5 47.625 28.85 x 0.4 11.54 8000 60 21 81 47.625 3335 x 0.4 13.34 10000 80 89.5 16.5 96.5 47.625 48.85 x 0.4 1954 12000 80 91 13 93 47.625 45.35 x0.4 18.14 Table4 Corrctions and Calculations R Frq. P's Ps ELC& SPL (Hz) dBHL SPL- transfer functions x0.4 'REQ Baseline 250 20 23.5 43.5 47.625 4.15 x 0.4 -1.66 500 -10 1.5 7.5 -25 47.625 -50.15 x 0.4 -20.05 750 0 1.5 5.5 5.5 47.625 -41.12 x0.4 -16.85 1000 5 7 12 47.625 -35.65 x 0.4 -1426 1500 0 65 6.5 47.625 -41.15 xOA.4 -16.46 2000 IS 7 22 47.625 -25.65 x0.4 -10.26 3000 45 5.S 50.5 47.625 2.85 x 0.4 1.14 4000 30 2.5 32.5 47.625 -15.15 x 0.4 -6.06 6000 30 16.5 46.5 47.625 -1.15 x 0.4 -0.46 8000 20 21 41 47.625 6.65 x OA -2.66 10000 60 16.5 76.5 47.625 28.85 x 0.4 11.54 12000 75 13 88 47.625 4035 x 0.4 16.14

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-19- The REQ equalisation curves for both ears'are illustrated graphically in Figure4. A comparison of Figure 4 with Figure 2 will confirm that the patient's right and left hearing thresholds [HTL (SPL)] curves are identical.

00 A second clinical study was conducted in which 90 people who suffer from tinnitus participated. The participants were allocated with block randomisation into one of four treatment groups: one group to test a second generation total masking algorithm (TMP2),

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1 one to test the tinnitus retraining algorithfat(RP);one to empirically measure the current TRT approach of using low-level broadband noise stimulants, and a quasi-control group to receive counselling alone. The second study exceeded expectations, with dramatic levels of habituation experienced by more than three-quarters of the participants using spectrally modified music. The adoption of bibliotherapy and TRT-style counselling resulted in significant improvements in clinical outcomes for all treatment groups. However, counselling alone appeared to be insufficient treatment for most participants. An important finding was that the TRP group experienced the greatest mean improvements in tinnitus distress. The TMP2 stimulus group initially displayed a more rapid improvement, but the more gradual gains of the TRP group were sustained for longer, and ultimately were superior. There was little difference between the noise and counselling alone groups at post therapy-andfollow-up,.although.the mean improvements experienced by the counselling alone group were ultimately not statistically significant While all treatment groups recorded mean reductions in tinnitus distress over therapy, the two music groups ultimately appeared to be the most effective. Approximately three-quarters of the two music group participants experienced significant habituation to their tinnitus (TMP2 78.6%, TRP There were substantial reductions in hyperacusis scores for both music groups, and a slight reduction for the noise group. The group without acoustic stimulation (Counselling-only) displayed an increase in hyperacusis over the same period, strongly indicating that the provision of acoustic stimulation was a key ingredient in the hyperacusis improvements. The music group participants often reported that their hyperacusis levels tended to improve faster than their tinnitus perception.

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C1) 0c The clinical studies therefore suggest that total masking with music is more effective to facilitate a rapid improvement in distress and relaxation levels, despite the fact that intermittent masking with music eventually proved to be more effective on several r-- 00 measures. This indicates that a two-stage approach might be most efficient, whereby patients initially should employ a total masking algorithm to give a stronger sense of relief and control, then later switch to intermittent masking to remove the tinnitus detection.

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In the clinicaL studies, :.pre-recorded music: :.was spectrally modified using the predetermined masking algorithms, and re-recorded on audio cassette tapes for participants' use. This approach is unlikely to be acceptable for widespread clinical use, in view of the potential copyright infiingemcnt problems in some states or countries.

SPurchase of the rights to re-record music from selected recording companies is one means of circumventing this, or the commissioning of recordings specifically for this purpose. In one embodiment it is proposed to provide a programmable "black box" device for use by private practitioners The device thus envisaged can be programmed by a qualified audiologist to account for each individual's tinnitus and hearing loss characteristics, using the tinnitus masking algorithms and clinical protocols developed by the inventor. In one embodiment, the device may take the form of a musician's hearing aid-type device designed to spectrally.-modify. the.audio signal.as it enters the wearers cars. A more 2 0 preferred embodiment is to provide the device in the form of a "black box" which can be employed in conjunction with a PMP and has an input adapted to connect to the audio output headphone jack on the PMP. The device would have a standard headphone jack to which a conventional PMP headphone can be connected. In an alternative embodiment, a modified sound recording is automatically generated in the audiologist's clinic, tailored to the patient's audiometric configuration, using software accessed via the World Wide Web.

Figure 5 illustrates in schematic block diagram form a possible embodiment of a tinnitus rehabilitation "black box" device. The device 10 has an input 12 adapted to receive a twochannel stereo signal from the headphone output jack of a PMP. The device 10 also has an output 14 which provides a two-channel stereo signal, spectrally modified by a predetermined masking algorithm programmed into the device 10, which is suitable for listening to through a conventional PMP headphone. Preferably, the device 10 employs digital signal processing, and therefore the left and right input audio analog signal is converted to digital format in an analog to digital converter (ADC) 16. The digital output signal of ADC 16 is then sent to a digital filter 18 which filters the digitised audio signal in 00 accordance with a predetermined masking algorithm. The digital filter 18 modifies the C-i 5 intensity of the audio signal at selected frequencies in accordance with the masking algorithm.

The filter characteristic of. the..digital filter 18 .may be programmed manually using thumbwheels. However, more preferably the digital filter 18 is programmed electronically 1o by means of a microprocessor-based controller 20 having a communications port 22 that may be connected to a desk top computer. Using a custom-designed software program which accompanies the device 10, an audiologist or other hearing aid dispenser can program the device 10 by means of a graphic user interface.(GUI) which facilitates the input of the required clinical data into the non-volatile memory of the controller 20. Thus, for example, the clinical audiologist would simply enter the patient's pure tone hearing level thresholds at each of the 10 discrete frequencies from 0.25 to 12kHz. The audiologist may also be required to enter the two adjacent least hearing loss frequencies the hearing threshold- at the frequency of tinnitus pitch match and/or the two adjacent greatesthearingloss frequencies.(C). Either the software or the controller 20 will then use these figures to calculate the baseline value, and employ the predetermined masking algorithm to calculate the required equalisation values. These values are employed by the controller 20 to set the filter constants at each frequency in the digital filter 18.

The device 10 may also include an additional signal processing means 24, which is also under control of the controller 20, for providing further'spectral modification of the digital audio signal after filtering by the digital filter 18. The spectrally modified audio signal is then converted back to analog format in a digital to analog converter (DAC) 26. An amplifier 28 may be provided to control the amplitude of the analog output signal provided at the output 14 of the device. It will be understood that each of the digital components of the device 10 may be integrated into a single integrated circuit, so that the dimensions of the device 10 can be made quite small and the device therefore remains inconspicuous.

Further investigation has revealed that the proprietary algorithms or digital processing of 0C) the audio signal may be entirely sofiwmr-based, facilitating the production of a stored music medium (compact disc or alternative format) for playback by the tinnitus sufferer on a standard personal sound reproduction system, such as a personal music player (PMP).

'with headphones. In this embodiment the method of providing a tinnitus rehabilitation sound recording- takces Til.ladvantage oft he-speed-cand economies provided by the Internet for fast digital communications and remote processing power. With no more than a desktop personal computer (PC) wAith CD-writing capablity, the ability to provide a custormised tinitus rehabilitation sounid recording can be placed at the fingertips of the audiologist 'By utilising the reach of the World Wide Web and developing an application service provider (ASP), (also described as "on-line operating software"), the method can be extended to provide tinnitus relief and treatment to a global mark et. Figures 6 and 7 illu~stae in flowchart form a preferred method of providing a timuritus rehabilitation sound recording utilising the world Wvide web and the ser-vices of an Asp.

The process commences in the audiologist's clinic where the patient consults 100 with the audiologist. ni.-audioogit.enterslo12 th.jptient's personal details into the -appropriate fields in an application form located oni a proprietary website. The audiologist then conducts 104 an audiogramn on the patiet's left and right ears. The audiogramn is converted into an appropriate digital format and stored 106, on the audiologist's PC The audiologist may then activate 108 the application service provider (ASP) via the wcbsite, which automatically acce 'sses: the patient data, including the digital audiogram, and transmits it via the website to-the ASP.

Data. is received 200 by the ASP and split into left and right ear processing channels. A central processing server (accessed via the ASP) houses the software containing the Proprietary algorithms for converting the patient data to a digital filtering format herein referred to as a Masking Profile. This Masking Profile is then transmitted back to the audiologist's PC The central processing server uses the digital audiogram to determine 2 0 2 L, 202,~ the pure tone level thresholds at each of the predetermined frequencies for the

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-23left and right ears. The software ascertains 204 the two adjacent greatest hearing loss frequencies in the greatest hearing loss ear, and also the two adjacent least hearing loss Sfrequencies in the least hearing loss car. In each of steps 206, 208,, 210, 212, 2 1 4 216

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00 and 206,, 2 08t, 2 10 2 12 R, 214,, 2 16 the tinnitus retraining protocol algorithm is applied to the left ear and right ear levels respectively, as is illustrated graphically in Tables 3 and 4 above.

In steps 218, 220.and 222 the baseline:value is.calculated, which is subtracted from each of the transformed threshold values for the left and right ears at 210 L, 210,. The left and right car Required Equalisation Response (REQ) values are then transnitted 224 to the audiologist's PC via the ASP website. The website, which is visible on the audiologist's PC, notifies 226 the audiologist that the REQ values are being downloaded onto the audiologist's PC, and also prompts 302 the audiologist to insert a music CD into a CD player connected to the PC. The audiologist is also prompted 304 to insert a blank CD into the CD writer connected to his PC. It is to be understood that any suitable audio recording may be employed, preferably a music recording, stored on any suitable storage medium, such as a compact disc, audio cassette or MP3 card. Typically, the patient is offered a choice of music CD's, for which the appropriate copyright licence fees have been paid, to be.used as.-the- base recording. An audio software application on the audiologist's PC accesses 306 the CD recording 308 and stores 310 the audio data to a file in the memory ofthe PC.

Proprietary software accessed by the ASP online reads the audio files stored in the PC, splits- the signal into left and right stereo signals and converts them to Fast Fourier Transform 312 (FFT) format 314. Meanwhile, the REQ data received by the audiologist's PC is allocated 316 a channel reference (ie left channel data and right channel data 318).

The software then converts 320 this left and right channel data into left and right Masking Profiles 322 respectively. Software provided on the audiologist's PC accesses 324 and applies the Masking Profiles to the right and left FFT signals for each of the stored songs in order to produce the left and right channels of the spectrally modified music signal.

Proprietary software 326 converts 326 the modified left and right signals back to. the frequency domain for playback as a conventional audio file. The modified audio files 328,

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c -24one corresponding to each of the songs on the original music CD, are then utilised 330 by the CD Writer Software stored in the audiologist's PC, and are written to a blank CD 332.

00 The advantage of using an ASP and the audiologist's PC is that the amount of data transmitted and the processing power required by the server is in relative tens, very restricted web page; only qualified audiologists having access. Additional security measures such as 'one-time-only-downloads' or limiting the time the data is available on the website are also possible.

The consultation can easily be held in conjunction with a therapy session with the audiologist or as part of a coordinated therapy regime of on-going treatment. Posible revenue streams include the download of the proprietary software from the website and a royalty on each'datadoRnload;-ie for each CD:made (not per patient, as:each patient may wish to modify more than one CD). The Internet website could also provide a number of other services to assist in the relief of and treatment oftinnitus and hyperacusis.

Thus, while music is the preferred embodiment CDs can also be produced using noise, environmental sounds, pure tones or even speech signals if this is strongly preferred by the sufferer. The more computer-literate sufferers could enter their audiogram details without the help of an audiologist. When the audiologist or hearing aid dispenser does not have a CD burner, facility will be available for the CD to be produced at the ASP or other site, then posted to the clinic. As the data transmission speed of the Interet significantly increases, facility will be available for the processing of the audio signal to be performed within the ASP server if requied.

Now that several embodiments of the tinnitus rehabilitation method and device have been described in detail, it will be apparent that the described method and device for providing

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relief for persons suffering from tinnitus has a number of significant advantages over prior art techniques, including the following: 00 by facilitating the use of a personal music player with relaxing music, it is much C 5 more acceptable to patients than conventional hearing aid-style maskers; 0 (ii) it compensates for high frequency hearing loss which accompanies the tinnitus in thus providing .the broadest spectrum ofacoustic stimulation; (iii) the masking algorithms developed to spectrally modify the masking/retraining audio stimuli correct for each individual's particular hearing loss configuration as well as accounting for the effects of loudness recruitment, thus enabling effective stimulation at a relaxing intensity level; (iv) intermittent tinnitus masking with music can provide a form of systematic desensitisation to the disturbing effects of tinnitus; and, spectrally modified sound recordings produced using the masking algorithms reduce tinnitus distress.to.the.point where it was no longer significantly interfering with quality of life in more than 75% of trial participants. Significant reductions in MMLs were measured, and hyperacusis levels had significantly improved.

It will also be apparent to persons skilled in the audiological and electronics arts that numerous variations and modifications may be made to the described method and device, in addition to those already described, without departing from the basic inventive concepts. For example, a masking algorithm in accordance with the invention may be employed to set the frequency response of existing tinnitus maskers which use bands of noise, rather than music, to achieve similar results. Varioustypes of noise, pure tones aid speech could also be used in addition to music. The same masking algorithms may also be employed in existing wireless receiver devices, (such as the Starkey Silentia Set), or through hearing aid induction coil systems. Furthermore, the mathematical algorithms used for calculating the individual prescription of the audio signal may differ from the ~KI -26above described algorithm, and extra sounds may also need to be inserted. However, other embodiments of the invention would be consistent with the. essential clinical technique that is intended to provide a modification of the intensity of audio signals to 00 account for hearing levels, specifically for the relief and/or tetment of tinnitus and! hyperacusis. All such variations and modifications are to be considered within the scope of the present invention, the nature of which is to be determined from the foregoing description and the appended claims.

Claims (62)

1. A method of providing treatment for an auditory system disorder comprising: generating a treatment signal by accentuating frequency components in a signal in a frequency range where a person has deficient hearing and ameliorating any objectionable nature in the treatment signal by including coherent signal components within a general listening range of the person. 0 2. The method of providing treatment for an auditory system disorder as claimed in claim 1, wherein any objectionable nature in the treatment signal is further ameliorated by attenuating the signal in frequencies where a person's hearing is relatively less deficient.

3. The method of providing treatment for an auditory system disorder as claimed in claim 1, wherein the auditory system disorder is tinnitus and the treatment signal is a masking signal.

4. The method of providing treatment for an auditory system disorder as claimed in claim 3, wherein the treatment signal includes a frequency substantially similar to the tminnitus. The method of providing treatment for an auditory system disorder as claimed in claim 1, wherein the treatment signal is a highly dynamic signal whose spectral content and intensity constantly varies over time.

6. The method of providing treatment for an auditory system disorder as claimed in claim 5, wherein the treatment signal is a music signal.

7. A computer readable recording medium on which is recorded a program for carrying out the auditory system disorder treatment method as defined in claim 1.

8. A carrier signal encoded to transmit, via a global computer network, a computer executable program for carrying out the auditory system disorder treatment method as defined in claim 1.

9. A method of providing treatment for an auditory system disorder of a patient comprising: exposing the patient to a treatment signal; and manipulating application of the treatment signal to the patient so that the patient's perception of the auditory system disorder is modified on a neural level wherein the patient is gradually desensitized to the auditory system disorder over time, to thereby habituate the patient to the auditory system disorder. -28- O

10. The method of providing treatment for an auditory system disorder of a patient as aclaimed in claim 9, wherein the treatment signal is specifically tailored to the patient. 0 11. The method of providing treatment for an auditory system disorder of a patient as claimed in claim 9, wherein treatment signal includes components that are specifically tailored to each ear of the patient. IN 12. The method of providing treatment for an auditory system disorder of a patient as 00 claimed in claim 11 wherein treatment signals are delivered in a binaurally balanced N way. O 13. The method of providing treatment for an auditory system disorder of a patient as O claimed in claim 9, wherein the treatment signal is a highly dynamic signal whose spectral content and intensity constantly varies over time.

14. The method of providing treatment for an auditory system disorder of a patient as claimed in claim 13, wherein the treatment signal is a music signal. The method of providing treatment for an auditory system disorder of a patient as claimed in claim 9, wherein the treatment signal includes at least an active treatment portion which is spectrally modified to patient specifications.

16. The method of providing treatment for an auditory system disorder of a patient as claimed in claim 9, wherein the treatment signal includes at least one passive treatment portion such that delivery of the active treatment portion is more comfortable to and possibly not perceived by the patient, whereby the patient becomes habituated to the auditory system disorder by gradually increasing the exposure to the auditory system disorder during treatment.

17. The method of providing treatment for an auditory system disorder of a patient as claimed in claim 9, wherein the auditory system disorder is tinnitus and the treatment signal is a masking signal.

18. The method of providing treatment for an auditory system disorder of a patient as claimed in claim 9, wherein the treatment signal is a music signal.

19. The method of providing treatment for an auditory system disorder of a patient as claimed in claim 9, wherein the treatment signal accounts for a person suffering from a condition characterized by reduced tolerance to sound. The method of providing treatment for an auditory system disorder of a patient as claimed in claim 19, wherein the condition includes hyperacusis. -29-

21. The method of providing treatment for an auditory system disorder of a patient as .,claimed in claim 9, wherein the treatment signal is applied intermittently to the patient to 0 provide active treatment periods in which the auditory system disorder is actively treated and passive treatment periods in which the auditory system disorder may exist but not necessarily be perceived by the patient. CN 22. The method of providing treatment for an auditory system disorder of a patient as r- 00 claimed in claim 9, further comprising providing the treatment signal via an external device. O 23. The method of providing treatment for an auditory system disorder of a patient as claimed in claim 22, wherein the external device comprises headphones, earphones or wireless earphones.

24. The method of providing treatment for an auditory system disorder of a patient as claimed in claim 9, further comprising providing the treatment signal via an internal device.

25. The method of providing treatment for an auditory system disorder of a patient as claimed in claim 9, further comprising providing the treatment signal via a hearing insert.

26. A method for providing treatment for a patient's auditory system disorder, comprising: measuring the patient's hearing loss characteristics; calculating an optimal gain for each hearing threshold at each frequency in each ear; and applying the contour curve to a dynamic input signal to obtain an individually prescribed ideal output signal.

27. The method for providing treatment for a patient's auditory system disorder as claimed in claim 26, wherein at least a main portion of the output signal is centered near a mid point of two extremes of the patient's hearing configuration.

28. The method for providing treatment for a patient's auditory system disorder as claimed in claim 26, wherein the relevant transform values for dBHL to dBSPL, optimal gain multiplier functions, or frequency-dependant loudness weighting curves are taken into account to provide a balanced perception of the signal in each ear.

29. The method for providing treatment for a patient's auditory system disorder as Sclaimed in claim 26, wherein the auditory system disorder is tinnitus and the output O signal is generated by spectrally modifying an audio signal as it enters the wearer's ears. The method for providing treatment for a patient's auditory system disorder as claimed in claim 26, wherein the auditory system disorder is tinnitus and the output N, signal is a masking signal. 00 31. The method for providing treatment for a patient's auditory system disorder as claimed in claim 26, wherein the treatment signal is a highly dynamic signal whose O spectral content and intensity constantly varies over time. N 10 32. The method for providing treatment for a patient's auditory system disorder as claimed in claim 31, wherein the treatment signal is a music signal.

33. The method for providing treatment for a patient's auditory system disorder as claimed in claim 26, wherein the centering is bi-lateral centering and is performed by determining the greatest hearing ear of the patient and noting the hearing thresholds at a greatest hearing loss frequency region; determining the least hearing loss ear and noting the hearing thresholds at the least hearing loss frequencies; and calculating a midpoint between the two extremes to define a baseline from which approximately equal amounts of acoustic energy can be added or subtracted, thus maximizing usable range while minimizing distortion.

34. The method for providing treatment for a patient's auditory system disorder as claimed in claim 26, wherein the centering is performed by determining the midpoint between the desired ear's worst hearing threshold region and the same ear's best hearing threshold region, to define a baseline value from which approximately equal amounts of acoustic energy can be added or subtracted, thus maximizing usable range while minimizing distortion. The method for providing treatment for a patient's auditory system disorder as claimed in claim 26, wherein the perception of the signal in each ear is maintained by a correlation in time between two different signals.

36. A method of treating tinnitus comprising generating a treatment signal by accentuating frequency components in a signal in a frequency range where a person has deficient hearing and which treatment signal includes a frequency substantially similar to the tinnitus. -31-

37. A method for treating tinnitus as defined in claim 36, further comprising ameliorating any objectionable nature in the masking signal by including coherent signal O components within a general listening range of the person. (,1

38. A method for treating tinnitus as defined in claim 37, wherein the treatment signal is a music signal. N, 39. A computer readable recording medium on which is recorded a program for 00 carrying out the tinnitus treatment method as defined in claim 37.

40. A carrier signal encoded to transmit, via a global computer network, a computer executable program for carrying out the tinnitus treatment method as defined in claim 10 37.

41. The method of providing treatment for an auditory system disorder of a patient as claimed in claim 1, wherein the treatment signal accounts for a person suffering from a condition characterized by reduced tolerance to sound.

42. The method of providing treatment for an auditory system disorder of a patient as claimed in claim 41, wherein the condition includes hyperacusis.

43. The method of providing treatment for an auditory system disorder as claimed in claim 37, wherein the treatment signal is a highly dynamic signal whose spectral content and intensity constantly varies over time.

44. A tinnitus rehabilitation method for providing relief to a person suffering from the disturbing effects of tinnitus, the method comprising: providing a treatment signal; modifying the treatment signal to include troughs and peaks wherein the modified treatment signal intermittently masks the tinnitus during at least one of the peaks and does not fully mask the tinnitus during at least some of the troughs.

45. A tinnitus rehabilitation method as defined in claim 44, wherein the treatment signal is audio signal.

46. A tinnitus rehabilitation method as defined in claim 45, wherein the audio signal is a music signal.

47. A tinnitus rehabilitation method as defined in claim 46, wherein the music signal provides a relaxing stimulus on at least one of a psychological, acoustic, and neural level.

48. A tinnitus rehabilitation method as defined in any one of claims 44 to 47, further comprising providing the treatment signal to the person via an external device. -32- r, 49. A tinnitus rehabilitation method as defined in claim 48, wherein the external O device comprises headphones. O A tinnitus rehabilitation method as defined in any one of claims 44 to 47, further comprising providing the treatment signal to the person via an internal device.

51. A tinnitus rehabilitation method as defined in claim 50, wherein the internal device 1 comprises a hearing insert. 00 52. A tinnitus rehabilitation method as defined in any one of claims 44 to 51, wherein 1 the modifying is based upon a predetermined masking algorithm.

53. A tinnitus rehabilitation method as defined in any one of claims 44 to 52, wherein the modifying accounts for a person suffering from a condition characterized by reduced sound tolerance.

54. A tinnitus rehabilitation method as defined in claim 53, wherein the condition includes hyperacusis. A computer readable recording medium on which is recorded a program for carrying out the tinnitus rehabilitation method as defined in any one of claims 44 to 54.

56. A carrier signal encoded to transmit, via a global computer network, a computer executable program for carrying out the tinnitus rehabilitation method as defined in any one of claims 44 to 54.

57. A multi-stage tinnitus rehabilitation method for providing relief to a person suffering from the disturbing effects oftinnitus, the method comprising: providing a treatment signal; during a first treatment stage, fully masking the tinnitus whereby the person does not perceive the tinnitus; and during a second treatment stage following the first treatment stage, modifying the treatment signal to include troughs and peaks wherein the modified treatment signal intermittently masks the tinnitus during at least one of the peaks and does not fully mask the tinnitus during at least some of the troughs.

58. A tinnitus rehabilitation method as defined in claim 57, wherein the treatment utilizes an audio signal.

59. A tinnitus rehabilitation method as defined in claim 58, wherein the audio signal is a music signal. -33-

60. A tinnitus rehabilitation method as defined in claim 59, wherein the music signal provides a relaxing stimulus on at least one of a psychological, acoustic, and neural O level.

61. A tinnitus rehabilitation method as defined in any one of claims 57 to 60, further comprising providing the treatment signal to the person via an external device. N, 62. A tinnitus rehabilitation method as defined in claim 61, wherein the external 00device comprises headphones. N, 63. A tinnitus rehabilitation method as defined in any one of claims 57 to 60, further comprising providing the treatment signal to the person via an internal device. 10 64. A tinnitus rehabilitation method as defined in claim 63, wherein the internal device comprises a hearing insert. A tinnitus rehabilitation method as defined in any one of claims 57 to 64, wherein the modifying is based on a predetermined masking algorithm.

66. A tinnitus rehabilitation method as defined in any one of claims 57 to 65, wherein the modifying accounts for a person suffering from a condition characterized by reduced tolerance to sound.

67. A tinnitus rehabilitation method as defined in claim 66, wherein the condition includes hyperacusis.

68. A computer readable recording medium on which is recorded a program for carrying out the tinnitus rehabilitation method as defined in any one of claims 57 to 67.

69. A carrier signal encoded to transmit, via a global computer network, a computer executable program for carrying out the tinnitus rehabilitation method as defined in any one of claims 57 to 67. A tinnitus rehabilitation method for providing relief to a person suffering from the disturbing effects oftinnitus, the method comprising: providing a music signal; and spectrally modifying at least a first portion of the music signal in selected frequency ranges tailored to the person to at least partially mask the tinnitus.

71. A tinnitus rehabilitation method as defined in claim 70, wherein at least a second portion of the music signal is unmodified, wherein the person remains comfortable and relaxed when transitioning from the second portion to the first portion of the music signal, thereby creating an environment in which discomfort to the person is diminished upon application of the first portion to the person. j -34-

72. A tinnitus rehabilitation method as defined in claim 71, wherein the first and csecond portions of the music signal are alternately and repeatedly provided to the person 0 for treatment.

73. A tinnitus rehabilitation method as defined in claim 71, wherein the first and second portions form a continuous signal. N, 74. A tinnitus rehabilitation method as defined in any one of claims 70 to 73, wherein 00 the modifying at least a first portion of the music signal utilizes a predetermined N, masking algorithm. A tinnitus rehabilitation method as defined in any one of claims 70 to 74, wherein the modified music signal provides a relaxing stimulus on at least one of a psychological, acoustic, and neural level.

76. A tinnitus rehabilitation method as defined in any one of claims 70 to 75, wherein the person perceives intermittent masking of the tinnitus.

77. A tinnitus rehabilitation method as defined in any one of claims 70 to 76, further comprising: during a first treatment stage, delivering full masking of the tinnitus to the person; and during a second treatment stage following the first treatment stage, delivering intermittent masking of the tinnitus to the person.

78. A tinnitus rehabilitation method as defined in any one of claims 70 to 77, further comprising providing the music signal to the person via an external device.

79. A tinnitus rehabilitation method as defined in claim 78, wherein the external device comprises headphones. A tinnitus rehabilitation method as defined in any one of claims 70 to 77, further comprising providing the music signal to the person via an internal device.

81. A tinnitus rehabilitation method as defined in claim 80, wherein the internal device comprises a hearing insert.

82. A tinnitus rehabilitation method as defined in any one of claims 70 to 81, wherein the modified music signal accounts for a person suffering from a condition characterized by reduced tolerance to sound.

83. A tinnitus rehabilitation method as defined in claim 82, wherein the condition includes hyperacusis.

84. A computer readable recording medium on which is recorded a program for Scarrying out the tinnitus rehabilitation method as defined in any one of claims 70 to 83. A carrier signal encoded to transmit, via a global computer network, a computer executable program for carrying out the tinnitus rehabilitation method as defined in any one of claims 70 to 83. r, 86. A tinnitus rehabilitation method as defined in any one of claims 70 to 83, wherein 00 the selected frequency ranges are high frequency ranges which are boosted. N 87. A tinnitus rehabilitation method as defined in claim 86, wherein the high Sfrequency ranges are in the frequency range of about 3-16 kl-lz.

88. A tinnitus rehabilitation method as defined in claim 87, wherein the high frequency ranges are in the frequency range of about 6-12 kHz.

89. A tinnitus rehabilitation method as defined in claim 86, wherein the selected frequency ranges are low frequency ranges which are attenuated. A carrier signal encoded to transmit, via a global computer network, a computer executable program for carrying out a tinnitus rehabilitation method substantially as herein described with reference to any one of the embodiments of the invention illustrated in the accompanying drawings and/or examples.

91. A multi-stage tinnitus rehabilitation method substantially as herein described with reference to any one of the embodiments of the invention illustrated in the accompanying drawings and/or examples.

92. A computer readable recording medium substantially as herein described with reference to any one of the embodiments of the invention illustrated in the accompanying drawings and/or examples. DATED this 12 th day of October 2004 Shelston IP Attorneys for: Curtin University of Technology