SE531690C2 - Adjustment and verification procedure for direct bone conductive hearing aids - Google Patents

Description

20 25 30 35 5213 :! E50 A1 person's dynamic hearing area to ensure that the amplified speech will be audible to the listener. In the second method, a one-time measurement is first made in the ear canal using a probe microphone. Another one-time measurement is then made in a 2-cc Coupler. The difference between these two measurements (known as the difference between the real ear and the 2-cc Coupler - real ear to coupler difference; RECD) can be used to transform the hearing aid's sound pressure output level (SPL) measured on a 2-cc coupler relative to the real ear. response, when placed in the ear canal of a patient, as the unique acoustic transform is known.

Both the in-situ ear and the coupling-based verification procedure for air-conducting hearing aids have proven to be valid and reliable (Scollie & Seewald, 2002) and both procedures allow direct comparisons of hearing aid output level characteristics with the dynamic hearing range on a personal basis.

Not everyone uses air-conducting hearing aids. If we assume that a hearing-impaired patient has an adequate residual sensory-neural inner ear function, some patients may be candidates for direct bone-conducting hearing aids. Usually, a skin-penetrating (percutaneous) titanium implant is placed in the parietal bone of the head and used to anchor a direct bone-conducting hearing aid, see e.g. BAHA sold by Cochlear Corp. Although it has been clinically available for many years, valid and reliable fitting and verification procedures for direct bone conduction hearing aids have not become available.

State of the art Today, a verification of direct bone-conducting hearing aids usually takes place in one of two ways: patients are asked to tell about their subjective experiences of the volume and sound quality of the hearing aid based on an experimental ("trial and error") basis. With the device connected to the patient and during a conversation with the audiologist, the volume control and the high / low frequency controls are adjusted until the patient considers that the device "sounds best" to them. while the sound field thresholds with the device in place, the tester receives information about the faintest sounds but provides only limited information about the audibility of speech at speech levels.

In addition, the sound field thresholds with the device in place have been shown to be invalid and unreliable (see Hawkins, 2004; Seewald et al., 1996). 10 15 20 25 51131 EEE? Summary of the Invention The present invention provides a method for relating the patient's hearing ability to the gain characteristics of the direct bone conducting hearing aid in the same units (mechanical quantities) and with a common reference point. First, hearing thresholds and discomfort levels are measured with e.g. a direct bone-conducting BEST vibrator in which an accelerometer (eg piezoelectric accelerometer) is attached to its back and the acceleration levels associated with the dynamic hearing range are measured directly at the patient's implant (reference point). Furthermore, the mechanical output of the direct bone conduction hearing aid can also be measured directly at the implant by attaching an accelerometer to a BEST vibrator and then the output of the apparatus can be compared directly with the patient's hearing discomfort levels and hearing thresholds.

However, these acceleration level units can be converted to equivalent power levels.

The reason for this transformation is that the power output level of the hearing aid itself can be measured objectively on an artificial "skull simulator". When the dynamic hearing range is defined in the corresponding power levels, the output level of the bone-conducting hearing aid can be directly compared with the patient's unique hearing characteristics. The output frequency response of the hearing aid can be manipulated and measured on the artificial skull simulator and compared with the dynamic range of that hearing, in order to be able to measure verify that the fit is adequate on each patient.

With alternative methods, the force levels can be measured directly on the patient with a force meter mounted on the front or indirectly through a constant force-generating vibrator.

Although transcutaneous (inductive signal transmission) direct bone conduction hearing aids with implanted vibrator are not yet available on the market, the present invention can also be applied there. iïšš fl ii fï; Detailed description Definitions Direct bone conduction hearing aids: Direct bone conduction hearing aids are defined as devices in which the speaker (vibrator) is attached directly to the skull without intermediate skin and soft tissue. These devices can either be skin penetrating, i.e. that the vibrator is connected to a skin penetrating implant attached to a fixture integrated with the skull bone or the vibrator can be implanted under the skin, where the driving side of the vibrator is connected to the skull bone (under the skin). Such subcutaneously placed vibrators have an outer housing of titanium.

Sound pressure level (SPL): Whenever possible, the sound pressure level (SPL) was used as the objective measure of sound pressure, where SPL dB refers to 20 | .i Pascal.

Acceleration level (A): For bone conduction applications (hearing via the skull), Acceleration can be used as the objective vibration measure where A dB refers to 1 m / sz.

Force level (F): Instead of Acceleration, the Force can be used as a vibration measure where F dB refers to lu Newton.

Hearing Thresholds (HT): Hearing thresholds are defined as the faintest sound a person can perceive at any given frequency. There are several methods for determining hearing thresholds such as e.g. "L-lughson-Westlake ascending technique" Hearing threshold levels can be measured in several units such as Sound Pressure Level (SPL), Acceleration Level (Am) or Power Level (F HT).

Discomfort Levels (LDL): The discomfort levels are defined as the highest noise a person can tolerate at each frequency. There are several procedures for determining the levels of discomfort described in Hodgett's 2007 (dissertation). Discomfort levels can be measured in several units such as Sound pressure level (SPL), Acceleration level (Am) or Krait level (Fm). 10 15 20 25 30 35 LT * »du» there '. = LD C11 Mechanical impedance (2): The mechanical impedance is defined by Z = F / v (applied force / response speed). The velocity is determined by v = Aljw where A is the acceleration, j is the complex constant and w is the angular frequency. By using these relations in the same connection point, the Acceleration levels (A) can be converted to Power levels (F) and vice versa according to F = A * Z / jw.

Acceleration-frequency-response function (AFRF): The acceleration-frequency-response function is defined as output level acceleration (A) from a vibrator attached to a special load divided by the input voltage level to the vibrator's electrical terminals (Vin) ie AFRF = ANin. This ratio is determined for each patient for all frequencies of interest.

Force-frequency-response function (FFR, =): The force-frequency-response function is defined as the output level force (F) from a vibrator attached to an artificial shell-force measuring device divided by the input voltage level (Vin) to the vibrator's electrical terminals, ie. . FFRF = FNin. This ratio is determined once for all frequencies of interest.

Audiometric vibrator: An audiometric vibrator is defined as a vibrator, which transforms electrical energy into mechanical energy, to measure a patient's hearing thresholds and discomfort levels (LDL) at a mechanical stimulus. Such a vibrator can be of different types, e.g. BEST, but it must have an additional device / function that enables direct or indirect measurement of the mechanical stimulation level at a given input voltage.

BEST vibrator: A Balanced Electromagnetic Separation Vibrator (BEST) is a conversion principle described by Håkansson 2003 and in patents SE Patent No: 0000810-2, SE Patent No: 0201441-3, and SE Patent No: 0600843-7.

Artificial skull force measuring device: An artificial skull force measuring device sometimes called Skull Simulator is a device that has the ability to objectively measure the power output level from a direct bone-conducting hearing aid, such as the. described by Håkansson 1989 or SE patent No: 850241 i-5. 10 15 20 25 30 35 5511! Force meter: A force meter de fi nieres as a measuring device, which is capable of measuring the force at the point of contact between the vibrator and the implant.

Constant force vibrator: A constant force vibrator is defined as a vibrator designed to deliver a constant force for a given size range of load impedances such as the range of skull impedances among patients. Such a vibrator has an output impedance that is sufficiently much lower than the patients' skull impedances. Such a vibrator can be cooled so that for a given electrical input voltage to the vibrator, there is a given power output level, which is independent of which patient it is connected to.

Prescribing rule: A prescribing rule is defined as a mathematical algorithm that uses individual patients' hearing parameters, such as hearing thresholds and discomfort levels, to put together an "optimal" (in some sense) mechanical output from a direct bone conduction hearing aid for a specific acoustic input.

Acousto-mechanical force targets (so-called force targets): Desired force output level from a vibrator for a given specific acoustic stimulus to a direct bone conduction device in accordance with a prescribed adaptation principle or algorithm.

Description The invention relates to a method for adapting and validating direct bone conduction hearing aids to a patient which is characterized in that: a. In a first step hearing threshold and discomfort levels are measured directly on the patient's bone anchored implants, b. In a second step these hearing threshold and discomfort levels are converted to the corresponding equivalent force thresholds (Fm) and discomfort levels (FLDL) on an artificial skull force measuring device, c. as a starting point for the final adjustment of the device. In a preferred embodiment, the acousto-mechanical power levels of the hearing aid are calculated according to some prescription rule at a specific acoustic input signal and then the properties of the device are measured and adjusted to achieve the power level. in a preferred embodiment, acceleration thresholds (Am), acceleration discomfort thresholds (Am) and the acceleration frequency response (AFRF) are measured on said scale-anchored implant on a patient with an audiometer vibrator. The power frequency response (FFRF) of the audiometer vibrator is also measured on an official ski power measuring device and then the FFRF / AFRF ratio is calculated which is then used to convert AHT and ALDL data to corresponding equivalent Fm and FLDL data. in a preferred embodiment, the acceleration threshers (Am), acceleration discomfort levels (Am) and acceleration frequency response (AFRF) are measured on the patient with an audiometric BEST vibrator where an accelerometer is applied to its back.

In a preferred embodiment, the patient's acceleration thresholds (AHT), acceleration discomfort levels (Arm) and acceleration frequency response (AW) are measured with an audiometric vibrator, where an accelerometer is applied to its front.

In a preferred embodiment, the forceps and the patient's discomfort levels are measured directly with a force gauge between the vibrator and the implant.

In a preferred embodiment, the patient's force threshold (FHT) and discomfort levels (FLDL) are measured indirectly with a constant force vibrator, for example a specially designed BEST vibrator.

In a preferred embodiment, the patient's force threshold (Fm) and discomfort levels (Ftot) are measured indirectly with a BEST vibrator, which acts as a constant force vibrator. In a preferred embodiment, the frequencies used are the usual audiometric frequencies. in a preferred embodiment, the frequencies are 125 to 8000 Hz, normally divided into standardized frequencies. in a further aspect of the invention it relates to an apparatus for carrying out the method, which apparatus comprises an artificial force measuring device, a test station. a 10 15 20 25 30 35 šíšš tšššít 2 speakers, a microphone, an audiometer (6) and an audiometric transducer including a sensor or a constant power output transducer. In a preferred embodiment thereof, it further comprises a direct bone conducting hearing aid.

A measurement set for the proposed adaptation and verification procedure.

Figure 1 shows a measurement set for applying the present invention to a patient i, which consists of an artificial skull force measuring apparatus ii, which generates a force signal to a computer-based sound test station iii. The computer-based audio test station provides a speaker iv with a signal, the sound of which is received by a reference microphone v, which provides an additional input signal to the computer-based audio test station iii. An audiometer we receive and transmit control signals (automatically or manually) from and to the computer-based audio test station iii, and supply a voltage signal to a Balanced Electromagnetic Separation Vibrator (BEST) vii which is defined as an audiometric vibrator and generates the vibration signal and provides an acceleration signal, an accelerometer 8a attached to its rear central part, to the computer-based sound test station iii. The microphone v is placed close to the microphone of the direct bone conduction apparatus ix, which is to be adapted to the patient i, and which excites the artificial skull force measuring apparatus ii. The determination of the patient's hearing thresholds and discomfort levels is measured in mechanical units on a titanium implant 10 on the patient in.

In addition, the hearing thresholds 11 and the discomfort levels 12 are displayed on the audio test station iii screen as well as certain hearing aid characteristics such as the hearing aid's maximum power output level (MPO) 13 and the hearing aid's noise floor 14. The hearing aid output level 15 can also be measured and displayed at a specific acoustic input. By comparing these data, a trained audiologist can adjust the characteristics of the device, to improve the rehabilitation of the patient's hearing.

To be more objective, the output level 15 of the hearing aid at a specific acoustic input signal can be compared with the calculated acousto-mechanical force measures 16 for the specific acoustic input signal calculated in accordance with some prescription rule.

The output level of the device can then be adjusted to match the power target curve for the specific acoustic signal.

Figure 2 shows an alternative embodiment where the audiometric vibrator has a front-connected accelerometer or force meter 8b i: "Ill im wm Figure 3 shows another embodiment, where the audiometric vibrator is designed to be a constant force vibrator So electrical input voltage.

References Hawkins, D, B. (2004). Lirnitations and uses of the aided audiogram, Seminars in Hearing (Vol. 25, pp. 51).

Hodgetts W. (2007) Contribution to better understanding of fitting procedures for a Baha (PhD thesis).

Håkansson, B. and Carlsson, P., (1989), Skull simulator for direct bone conduction hearing devices. Scandinavian Audiology, 18, 91-98.

Håkansson, B. E. V. (2003). The balanced electromagnetic separation vibrator a new bone conduction vibrator. Journal of the Acoustical Society of America, 113 (2), 818-825.

Scollie, S.D., & Seewald, R.C., (2002). Electroacoustic Veri fi catlon Measures with Modern Hearing Instrument Technology. Chapter 10 of the Proceedings for the Second International Conference 'A Sound Foundation Through Early Amplification' Chicago, lL.

Seewald, R. C., Moodie, K. S., Sinclair, S. T., & Cornellsse, L. E. (1996). Traditional and theoretical approaches to selecting amplification for infants and young children. ln F. H.

Bess, J. S. Gravel & A. M. Tharpe (Eds.), Amplification for children with auditory deficits (pp. 161-191). Nashville, TN: Bill Wilkerson Press.

SE Patent No: 0000810-2 An electromagnetic vibrator SE Patent No: 0201441-3 Apparatus for electromagnetic vibrator SE Patent No: 0600843-7 Method for manufacturing balanced vibrators SE patent No: 8502411-5 Test equipment for direct bone conducting apparatus

Claims (12)

E35 E50 PATENT REQUIREMENTS Method for adaptation and verification of direct bone conduction hearing aids characterized in that a. In a first step hearing threshold and discomfort levels are measured directly on the patient's bone-connected implants, b. In a second step these hearing threshold and discomfort levels are converted to corresponding equivalent force equivalents) and discomfort levels (FLDL) on an artificial skull force measuring device, c. in a final step, the power output levels from the direct bone conduction hearing aid are measured in a free sound field with the device attached to said skull force measuring device and compared with FHT and FLDL as a starting point for a final adjustment of the device. A method according to claim 1, wherein the acousto-mechanical force measurements are calculated for the hearing aid in accordance with any prescription rule at a specific acoustic input signal and then the properties of the apparatus are measured and adjusted to achieve the force measurements. A method according to claim 1, wherein the acceleration thresholds (AHT), the acceleration discomfort levels (Am) and the acceleration frequency response (AFRF) are measured on said bone-connected implant on the patient and the force frequency response (FFRF) is measured on an artificial skull force measurement device. is used to convert Am and ALDL data to corresponding FHT and Fm data. Apparatus according to claim 3, wherein the acceleration thresholds (Am), the acceleration discomfort levels (ALDL) and the acceleration frequency response (AFRF) are measured on the patient with an audiometric BEST vibrator where an accelerometer is applied to its back. A method according to claim 3, wherein the patient's acceleration thresholds (Ami acceleration discomfort levels (Atol) and acceleration frequency response (AFRF) are measured with an audiometric vibrator, where an accelerometer is applied to its front. A method according to claim 1 with which the patient's force threshold and discomfort levels are measured directly with a force gauge between the vibrator and the implant. Method according to claim 4, with which the patient's force threshold (F in) and discomfort levels (Fm) are measured indirectly with a constant force vibrator, 55 "? SSU Apparatus according to claim 7, wherein the patient's force threshold (Fm) and discomfort levels (FLDL) are measured indirectly with a BEST vibrator, which acts as a constant force vibrator. A method according to claim 1, wherein the frequencies used are the usual audiometric frequencies. A method according to claim 9, wherein the frequencies are 125 to 8000 Hz. Apparatus for performing the method according to claims 1-10, which comprises an artificial skull force measuring apparatus (2), a test station (3), a loudspeaker (4), a microphone (5), an audiometer (6) and an audiometric vibrator ( 7) including a sensor (Sa, 8b) or a constant rake output vibrator (8c). Apparatus according to claim 11, wherein it further comprises a direct bone conducting hearing aid (9).