Apparatus and method for measuring clinical hearing parameters

Abstract

This paper describes an apparatus and method for determining middle ear immittance for clinical hearing testing over a wide range of frequencies at ambient pressure, based on MEMS microphone technology and measuring acoustic pressure waves and corresponding acoustic velocity waves with a pressure-pressure probe. The method of the present invention is non-invasive, since it can measure the acoustic admittance of the ear entrance at ambient pressure without changing the static pressure in the patient's ear canal. Another advantage is that it can analyze the functional status of the ear over a wide frequency range. Furthermore, using the p-p (pressure-pressure) approach to measure the acoustic admittance of the ear allows the use of pressure probes, i.e., microphones, based on MEMS technology, thereby reducing the manufacturing costs of impedance probes.

Description

[Technical Field]

[0001] The present invention relates to an apparatus and method for measuring middle ear immittance for clinical hearing testing in a simple, non-invasive, reliable and economical manner.

[0002] Such inventions are based on MEMS microphone technology and the simultaneous measurement of acoustic pressure waves and corresponding acoustic velocity waves by pressure-pressure type probes.

[0003] The present invention is primarily directed to ear impedance measurement (also called tympanometry) and is intended for diagnostic use to determine the condition of the tympanic membrane of the middle ear in humans or other animals with an auriculo-tympanic system and ear canal, such as dogs or cats. [Background technology]

[0004] Classical tympanometry allows objective analysis of the functional status of the outer and middle ear and the diagnosis of major pathologies by transmitting monofrequency sound waves (usually around 226, 678, 800, and 1000 Hz) and evaluating the change in acoustic volume impedance measured at eardrum level as a function of artificially created pressure variations in the ear canal (usually in the range of -600 to +400 daPa).

[0005] The classical tympanometry method has its drawbacks: in fact, the classical tympanometry test is performed by an invasive method, by indirect measurement with single-frequency stimulation, by externally induced fluctuations of static pressure in the ear canal, which is particularly troublesome for infants and children.

[0006] As an alternative to classical tympanometry, a broadband tympanometry method using pv microprobes has been developed, which detects the dependence of the specific admittance of the system including the ear canal and eardrum on the frequency of sound waves varying from 50 Hz to 8 kHz at a constant static pressure. This method is based on a pv (pressure-velocity) microprobe using MEMS (microelectromechanical systems) technology, which can directly measure pressure and velocity values ​​in response to external stimuli.

[0007] However, this method has the disadvantages that the cost of the pv-type microprobe is high and the velocity probe is fragile and prone to breakage. [Prior art documents] [Non-patent literature]

[0008] [Non-Patent Document 1] Kren Monrad Nφrgaard et al.: “Reproducing ear-canal reflectance using two measurement techniques in adult ears”, The Journal Of The Acoustical Society Of America, American Institute Of Physics For The Acoustical Society Of America, New York, NY, US, vol.147, no.4, April 17, 2020 (2020-04-17), pages 2334-2344, XPO12246238, ISSN:0001-4966, DOI: 10.1121 / 10.0001094. Summary of the Invention [Problem to be solved by the invention]

[0009] The object of the present invention is to overcome the above-mentioned drawbacks and to provide a reliable, non-invasive and economical way to carry out clinical hearing tests regarding the functional status of the ear.

[0010] The measurement uncertainty of ear canal reflectance associated with conventional measurement techniques was investigated by reproducing ear canal reflectance measurements using two different measurement techniques, as reported in non-patent document 1 by Kren Monrad Nørgaard et al. [Means for solving the problem]

[0011] A particular subject of the present invention is a method for determining the admittance of an ear canal for a clinical hearing test, said method comprising at least one or more iterations of a procedure, each iteration being associated with a respective coupling configuration (Q, Q1, Q2) between the impedance probe and the ear canal, said procedure comprising: A. A known volume of air, V probe via its first end (3), a calibrated sealed impedance probe having The air volume V sealed inside the impedance probe probe and the air volume inside the ear canal, V canal and the total air volume V overall Forming The longitudinal axis of the impedance probe is substantially aligned with the longitudinal axis of the ear canal and coupling the ear canal to the ear canal. B. transmitting a broadband excitation sound signal s(t) into the ear canal via a speaker of an impedance probe, such speaker being located at a second end of the impedance probe opposite the first end; C. The impedance probe includes a microphone array (8) that outputs electrical signals r1(t) and r2(t), and the distance between the microphones is Δx along the longitudinal axis of the impedance probe. 12 a step (220) of directly detecting the acoustic pressures p1(t) and p2(t) returning from the ear canal at at least two points x1 and x2 located at D. Obtain and discretize the electrical signals r1(t) and r2(t) output from the microphone array;

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[0012] According to another aspect of the present invention, the calibration constants α and β and the calibration function Γ(ω m ) can be known a priori and optionally provided by the microphone manufacturer.

[0013] According to a further aspect of the invention, the excitation sound signal s(t) is generated over a time T less than 10 seconds, optionally equal to 2 seconds, more optionally equal to 1 second. sweep Minimum frequency F greater than 100 Hz over the min to a maximum frequency F less than 5000 Hz max The signal may be a sweep signal varying from 0 to 1, optionally a linear or logarithmic sinusoidal signal.

[0014] According to an additional further aspect of the present invention, the distance Δx 12 can be equal to 12 mm.

[0015] According to another aspect of the present invention, step B comprises: B.1. synthesizing a digital sweep signal s(n) by a signal generator; B.2. A sub-step of converting the digital sweep signal s(n) into a wideband excitation sound signal s(t) to be input to a speaker via a D / A converter; may include:

[0016] According to a further aspect of the invention, step D may be performed via an A / D converter synchronized with a D / A converter.

[0017] According to a further aspect of the invention, said calibrated frequency spectrum of admittance

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[0018] According to another aspect of the present invention, the impedance probe and the ear canal are coupled in a first coupling configuration (Q1), and the excitation sound signal s(t) is applied for a time period less than 1 second.

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[0020] A further particular subject of the present invention is a device for implementing a method for determining the admittance of the auditory canal according to any one of claims 1 to 7, said device comprising: An impedance probe configured to couple with the ear canal (6), a box-like body having a first end configured to be coupled to an ear canal; a speaker located near a second end of the box-like body opposite to the first end and configured to emit an excitation sound signal, the box-like body being sealed to contain an air volume V at atmospheric pressure; probe a speaker contained within the A microphone array housed inside a box-like body and configured to detect a return signal from the ear canal, the distance between which depends on the frequency of the excitation sound signal s(t) being Δx 12 a microphone array comprising at least a first microphone and at least a second microphone positioned at a frequency of 1000 kHz, each microphone configured to directly detect a return acoustic pressure p(x,t) as a function of time t and output an electrical signal r(x,t); an impedance probe having a control and processing device configured to control and process the input and output signals of the impedance probe and to perform steps B to L, a generating unit configured to generate a digital signal s(n) and transmit it to a speaker via a D / A converter board detachably coupled to the speaker; an acquisition sound board configured to acquire an output signal from the microphone array via an A / D conversion board detachably coupled to the microphone array (8); a control and processing device having An apparatus comprising: The impedance probe and the control and processing device are removably coupled therebetween.

[0021] According to another aspect of the present invention, the control and processing device may be further configured to perform step M.

[0022] According to a further aspect of the present invention, the box-like body may be hollow cylindrical in shape.

[0023] According to a further aspect of the invention, the device may be configured to receive a broadband excitation sound signal s(t) in the frequency range between 100 Hz and 5000 Hz, and the distance Δx 12 is equal to 12 mm.

[0024] According to another aspect of the invention, the second end includes an adapter configured for easy coupling with the ear canal, and optionally the adapter is detachable.

[0025] According to a further aspect of the invention, the adapter is frusto-conical in shape and is optionally made from rubber latex. [Effects of the Invention]

[0026] The advantages offered by the method according to the invention with respect to prior art solutions are numerous and significant.

[0027] The method of the present invention is non-invasive because it can measure the acoustic admittance of the ear entrance at ambient pressure without changing the static pressure in the patient's ear canal. Another advantage is that it can analyze the functional status of the ear over a wide frequency range. Furthermore, using the pp (pressure-pressure) technique to measure the acoustic admittance of the ear allows the use of pressure probes, i.e., microphones, based on MEMS technology, thereby reducing the manufacturing costs of impedance probes.

[0028] To measure acoustic admittance, the reciprocal of acoustic impedance, it is necessary to measure the pressure and velocity signals obtained at the entrance of the ear canal in response to a sound stimulus. The pp technique is based on the Euler acoustic wave equation and allows the reconstruction of the acoustic particle velocity signal by numerically integrating the acoustic pressure gradient signal over time. Although this choice is in many ways suboptimal from a metrological point of view, it is satisfactory in the frequency range required for the application, and the current commercial success of MEMS technology applied to pressure microphones has significantly reduced the manufacturing costs of the probes. [Brief explanation of the drawings]

[0029] The present invention will now be described by way of example, and not by way of limitation, in accordance with preferred embodiments thereof, with particular reference to the figures of the accompanying drawings.

[0030] [Figure 1] 1 is a schematic block diagram of a preferred embodiment of an apparatus for measuring the acoustic admittance of the ear according to the present invention; [Figure 2] 1 shows a flowchart of the algorithm executed by a first preferred embodiment of the method for measuring the acoustic admittance of the ear according to the present invention;

[0031] In the drawings, the same reference numbers are used for similar elements. DETAILED DESCRIPTION OF THE INVENTION

[0032] Because the ear canal is deformed, the air is constrained to vibrate substantially along the longitudinal axis of the ear canal, and therefore the velocity vector can be approximated by a velocity along the direction of said axis, which we have designated as the x-direction, or x-axis.

[0033] 1, the device 100 comprises an impedance probe 1 having a box-like body 2 with a first end 3 configured to be coupled to an external measurement environment, which in the case shown in FIG. 1 is a patient's ear canal 6. The box-like body 2 includes therein at least one speaker 4 positioned adjacent to its second end 5 opposite the first end 3.

[0034] The speaker 4 is arranged to emit a sound signal s(t) for input into the ear canal 6 .

[0035] The box-like body 2 of the preferred embodiment of FIG. 1 has a hollow cylindrical shape. Conventionally, the first end 3 is located at a position x along the x-axis. a is the origin of the x-axis, and x a =0 was set.

[0036] The box-like body 2 is rigid and optionally made of brass or hard metal. The box-like body 2 is sealed and contains a known volume of air V at atmospheric pressure. probe Coupling the impedance probe 1 through its first end 3 to the patient's ear canal involves coupling an air volume V probe and the air volume in the ear canal V canal is the total air volume V at atmospheric pressure overall Forming V overall =V probe +V canal In other words, the total volume V containing air at atmospheric pressure overall is bounded by the impedance probe and the ear canal when they are coupled.

[0037] Furthermore, this coupling is such that the axis passing through the geometric centres of the first end 3 and the second end 5, conventionally the longitudinal axis of the impedance probe, is parallel to and substantially coincides with the axis of the ear canal, i.e. the x-axis.

[0038] In a preferred embodiment, the first end 3 includes an adapter 7, optionally frusto-conical in shape and made of rubber latex, configured to facilitate coupling to the ear canal 6. The adapter 7 can be detachable for replacement or cleaning before use with a different patient.

[0039] The microphone array 8 is configured to detect return signals from the ear canal 6 and is housed within the box-like body 2. The microphone array 8 comprises a first microphone 9 and at least one second microphone 10, each configured to directly detect a return acoustic pressure p(x,t) as a function of time t at a first measurement point x1 and a second measurement point x2, respectively, and provide an electrical signal r(x,t).

[0040] The distance Δx between the first measurement point x1 of the first microphone 9 and the second measurement point x2 of the second microphone 10 12depends on the frequency of the signal of interest. Ideally, to reconstruct a velocity signal from pressure signals measured by two microphones, a different distance Δx should be used for each frequency, i.e., each wavelength, of the sound field to be measured.

[0041] In the preferred embodiment, an optimal distance is used to cover the operating frequency range. To reduce experimental errors in the reconstruction of the velocity signal due to errors in the finite-difference approximation at high frequencies, the measurement wavelength should be approximately six times larger than the distance between the two microphones. For example, if the distance between the probes is 50 mm, the high-frequency limit of the sound field, at which the experimental error increases significantly, is 1.25 kHz; if the distance is 12 mm, the high-frequency limit is 5 kHz; and if the distance is 6 mm, the high-frequency limit is 10 kHz.

[0042] For impedance measurements inside the human ear canal, the distance Δx 12 is equal to 12 mm to optimize the measurement of acoustic admittance in the frequency range of 100-5000 Hz.

[0043] In another embodiment of the invention, the microphone array 8 is arranged at different distances Δx from one another to obtain a more accurate reconstruction of the velocity signal for each range of frequencies. ij The microphones are arranged in a manner such that the number of microphones is greater than two.

[0044] The minimum distance on the longitudinal axis between the second end 5 and the center point x0 of the microphone array 8, i.e. the distance between the first measurement point x1 and the second measurement point x2, must be such that it minimizes the measurement error of the microphone array 8 due to its proximity to the sound source. In a preferred embodiment, this distance is equal to 35 millimeters.

[0045] The impedance probe 1 is detachably coupled to a control and processing device 11 configured to control and process input and output signals from the impedance probe 1. The control and processing device 11 includes a generation unit 12 configured to generate and transmit a digital signal s(n) to a speaker 4 via a D / A conversion board 13 detachably connected to the speaker 4, and an acquisition sound board 14 configured to acquire an output signal from the microphone array 8 by an A / D conversion board 15 detachably connected to the microphone array 8. The generation unit 12 and the acquisition sound board 14 are connected to each other. Optionally, the control and processing device 11 can be detachably connected to one or more devices, such as PCs, smartphones, tablets, etc., and / or one or more screens 16 configured to display signals controlled and processed by the control and processing device 11.

[0046] To measure the acoustic admittance in the ear canal, it is necessary to measure the acoustic pressure signal and particle velocity signal in the air obtained in response to a sound stimulus sent at its entrance, i.e., an input signal. The impedance probe 1 can indirectly measure the velocity signal by starting from two acoustic pressure signals detected at a distance Δx from each other along the axis of the probe itself, as shown in Figure 1.

[0047] In fact, considering a one-dimensional sound field in a medium of density ρ, the Euler acoustic equations that connect the acoustic pressure p(x,t) at a point in the sound field to the particle velocity v(x,t) are

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[0048] Using the finite difference approximation, the pressure gradient

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[0049] However, this approximation is only valid if Δx is small compared to the shortest wavelength of the measured sound field.

[0050] Substituting equation 3 into equation 2, the velocity is

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[0051] Similarly, the acoustic pressure can be estimated as the average of pressures p(A) and p(B).

[0052] Therefore, for impedance probe 1, the spatial derivative of pressure is expressed as its increment ratio Δx 12 and perform time integration to obtain the component of the velocity signal along the x direction.

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[0053] The pressure and velocity signals calculated by Equations 5-7 are usually referenced to the center point x0 between the two microphones, which is therefore the actual measurement point {p(x0,t);v(x0,t)}.

[0054] To identify a linear, time-invariant acoustic system, such as the human or mammalian ear canal, its transfer function must be known, allowing its response to sound waves of any frequency to be analyzed. However, studying impedance requires knowledge of both the acoustic pressure response and the acoustic velocity response in the frequency domain. Therefore, the optimal stimulus for measuring these responses must be capable of exciting the system over the entire frequency range of interest. Therefore, this stimulus must be generated by a signal with the same average temporal energy for each frequency component. For this reason, the calculation of admittance is based on the impulse response of a linear, time-invariant acoustic system, calculated from field measurements excited by a chirp or sweep signal. This signal is a frequency-modulated signal whose instantaneous frequency varies linearly with time.

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[0055] A flow chart of a preferred embodiment of the present invention of a method for measuring the acoustic admittance of the ear is shown in FIG. 2, the internal blocks of which correspond to the control and processing device 11 of the apparatus 100 of FIG.

[0056] Preliminarily, the impedance probe 1 is configured to measure the air volume V contained within the impedance probe 1. probe To calculate , the tympanometer is calibrated using standard calibration methods used in tympanometry, for example. For example, the classical method, known to those skilled in the art, uses three known air volumes: 0.2 cc, 2 cc, and 4 cc.

[0057] In a first step, the calibrated impedance probe 1 is coupled via its first end (3) to the ear canal 6 in a coupling configuration (Q), so that its air volume V probe and the air volume in the ear canal V canal and the total air volume V overall Forming V complessivo =V sonda +V canale and its longitudinal axis is parallel to and substantially coincides with the axis of the auditory canal, i.e., the x-axis.

[0058] The coupling configuration means a mutual contact arrangement between the impedance probe 1 and the ear canal 6 .

[0059] In step 200, the generation unit 12 generates, in other terms, synthesizes, an excitation chirp or sweep signal s(n), which signal is generated over a time T less than 10 seconds, optionally equal to 2 seconds, and further optionally equal to 1 second. sweep Between the min to a maximum frequency F less than 5000 Hz max In a preferred embodiment, the excitation sweep signal s(n) is a logarithmic or linear sinusoidal sweep signal. In step 210, the signal s(n) is converted to an analog signal s(t) via the D / A conversion board 13, and then transmitted from the control and processing device 11 to the speaker 4.

[0060] In step 220, a first acoustic pressure p1(t) and a second acoustic pressure p2(t) are measured directly at points x1 and x2 by a first microphone 9 and a second microphone 10, which respectively output a first electrical signal r1(t) and a second electrical signal r2(t) as a function of time. In step 230, the control and processing device 11, via the acquisition sound board 14, acquires the first electrical signal r1(t) and the second electrical signal r2(t) and converts them into corresponding discretized values ​​r1(n), r2(n) via the A / D conversion board 15, where:

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[0061] Since the A / D conversion board 15 is synchronized with the D / A conversion board 13, the electrical signals r1(t) and r2(t) are synchronized in time. That is, they are acquired in synchronization with the excitation signal s(t). In other words, the acquisition of the electrical signals must start exactly at the moment the excitation signal is emitted.

[0062] The number of discretized values ​​N depends on the measurement sampling, ie, the time resolution of the acquisition, and therefore also on the excitation chirp or sweep signal s(n) synthesized in step 200 .

[0063] In step 240, the control and processing device 11 calculates the impulse response of the ear canal 6 according to Equation 8, and obtains a first impulse response from the first microphone 9 and a first impulse response from the second microphone 10, respectively.

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[0064] The control and processing device 11 then calculates in step 250 such an impulse response

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[0065] The superscript "au" in the pressure impulse response and velocity impulse response indicates that they are quantities in arbitrary units [au].

[0066] Then, the pressure impulse response and the velocity impulse response

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[0067] The calibration constants α and β are obtained by methods known in the literature. See, for example, Stanzial D., Graffigna CE, "Protocol of Amplification and Phase Per Pressure-Velocity Measurement in a Reference Range for Progressive Piano Propagation," Associazione Italiana di Acustica, 44° Convegno Nazionale, Pavia, June 7-9, 2017, ISBN: 978-88-88942-54-4. Here, the velocity signal is the signal reconstructed from the microphone pressure signal. In other words, both the signal p(x0) and the signal v(x0) reconstructed from the signals p(x1) and p2(x2) are calibrated. In a further embodiment of the present invention, the calibration constants α and β are provided by the manufacturer of the microphone probe.

[0068] Once the pressure and velocity impulse responses have been converted into physical units, a Fast Fourier Transform is applied to them by the control and processing device 11 in step 270 to obtain the frequency spectrum of the pressure and velocity impulse responses

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[0069] Next, in step 280, the not yet calibrated admittance

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[0070] Finally, in step 290, a measurement of the calibrated admittance of the ear canal 6 is obtained by the control and processing device 11 as follows:

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[0071] Calibration curve Γ(ω m ) takes into account the different response of the microphone probe with changing frequency. In a further embodiment of the invention, the calibration function Γ(ω m ) is provided by the microphone probe manufacturer.

[0072] Admittance Spectrum

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[0073] Acoustic Admittance

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[0074] Analysis of the shape of the acoustic admittance resonance curve can provide diagnostically useful parameters such as the separation of the air volume in the ear canal and the air volume in the probe, and the absorption of energy by the eardrum.

[0075] In an embodiment of the method according to the invention, in which the microphone probe 8 comprises more than two microphone probes, the above-mentioned steps may be carried out by selecting the microphone probes 8 at mutually different distances Δx ij The frequency admittance curves are then resynthesized for each frequency segment processed.

[0076] The coupling between the impedance probe 2 and the ear canal 6 is adequate, i.e., the air volume V probe and the volume of air in the ear canal 6, V canal and is the total volume V of air at atmospheric pressure overall Since it is very important to form the impedance probe coupling to the ear canal, a preliminary procedure is optionally performed to identify the correct coupling of the probe to the ear canal. This preliminary procedure is based on identifying the admittance resonance. Once the resonance is identified, more accurate admittance measurements are performed to obtain clinical hearing parameters while maintaining the coupling of the impedance probe to the ear canal where the resonance occurs.

[0077] This preliminary procedure begins with coupling the impedance probe (1) to the patient's ear canal (6) in a first coupling configuration (Q1), e.g., from an operator;

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[0078] It is checked whether the resonance condition of the admittance is met, i.e. whether the peak of the admittance module corresponds to the zero crossing of its phase.

[0079] If a resonance condition occurs, the first coupling configuration (Q1) corresponds to the correct coupling of the probe to the ear canal and the procedure ends.

[0080] Next, the method maintains the first coupling configuration (Q1) and

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[0081] If a resonance condition does not occur, the method is repeated with a second coupling configuration (Q2) that is different with respect to the previous coupling configuration (Q1), e.g., the operator changes the relative positioning of the probe and the ear canal, and the fast sweep signal s fast (t) to calculate the second calibrated admittance

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[0082] In other words, a resonance in the admittance spectrum means that the impedance probe is correctly positioned relative to the ear, and more accurate measurements can be performed to determine admittance.

[0083] In a preferred embodiment of the method, if a resonance condition is identified, the control and processing device 11 alerts the operator, for example by emitting an audible signal or by sending a signal on a screen, allowing the operator to maintain the coupling configuration in which resonance occurs while performing the final measurement. Having described a preferred embodiment of the invention, it must be understood by those skilled in the art that other variations and modifications can be made without departing from the scope of protection thereof, as defined by the appended claims.

Claims

1. 1. A method for determining the admittance of an ear canal (6) for a clinical hearing test, said method comprising at least one or more iterations of a procedure, each iteration being associated with a respective coupling configuration (Q, Q1, Q2) between an impedance probe (1) and said ear canal (6), said procedure comprising: A. Known volume of air V ｐｒｏｂｅ The calibrated sealed impedance probe (1) having a first end (3) is connected to The air volume V sealed inside the impedance probe (1) ｐｒｏｂｅ and the air volume V inside the ear canal (6). ｃａｎａｌ and the total air volume V ｏｖｅｒａｌｌ Forming The longitudinal axis of the impedance probe (1) substantially coincides with the longitudinal axis of the ear canal (6). and coupling the ear canal (6) with the ear canal (6) in such a way that B. transmitting a broadband excitation sound signal s(t) into the ear canal (6) via a speaker (4) of the impedance probe (1), the speaker (4) being located at a second end (5) of the impedance probe (1) opposite the first end (3); C. The impedance probe (1) includes an electrical signal r １ (t), r ２ The microphone array (8) outputs (t) along the longitudinal axis of the impedance probe (1) such that the distance between the １２ At least two points x located respectively at １ , x ２ and the acoustic pressure p returning from the ear canal (6) １ (t), p ２ (t) directly (220); D. The electrical signal r output from the microphone array (8) １ (t) and r ２ (t) is obtained and discretized (230); [Equation 1] Then, the discretized signal r １ (n) and r ２ (n) E. First impulse response [Equation 2] and the second impulse response [Equation 3] The following formula [Equation 4] Calculating (240) by s'(t) is the time-reversed wideband sound signal s(t), FFT is the fast Fourier transform, and IFFT is the inverse fast Fourier transform; F. Measurement point x along the longitudinal axis of the impedance probe (1) ０ The acoustic pressure p １ (t) and p ２ Impulse response of (t) [Equation 5] and the impulse response of the air particle velocity [Equation 6] of, [Equation 7] Calculating (250) Such a measurement point x ０ is the point x １ and point x ２ and a step, which is the center point between G. Pressure and Velocity Impulse Responses [Equation 8] where the a priori known calibration constants α and β are [Equation 9] converting (260) into physical units of pressure and velocity by multiplying as follows: H. By fast Fourier transformation, the frequency spectrum of the impulse response for pressure and velocity, respectively [Equation 10] Below [0011] Calculating (270) as follows: ω ｍ are the discretized frequencies, m∈[1;N / 2], steps; I. Admittance [0012] the cross spectrum of the spectrum of the impulse response of acoustic pressure and the spectrum of the impulse response of acoustic velocity [0013] and an autospectrum of the spectrum of the impulse response of acoustic pressure. [0014] As a ratio between [Equation 15] A step (280) of calculating L. A priori known calibration function Γ(ω ｍ ) via the calibrated frequency spectrum of the admittance [0016] , the equation [Equation 17] and a step (290) of obtaining the Including, A method wherein said steps D to L are performed by a control and processing device (11).

2. 2. The method of claim 1, wherein the calibration constants α and β and the calibration function Γ(ω ｍ ) is a method provided by the microphone manufacturer.

3. The excitation sound signal s(t) is detected for a time T that is less than 10 seconds. ｓｗｅｅｐ A minimum frequency F greater than 100 Hz over the entire ｍｉｎ to a maximum frequency F less than 5000 Hz ｍａｘ 3. The method according to claim 1, wherein the sweep signal varies from

4. The distance Δx １２ The method according to any one of claims 1 to 3, wherein is equal to 12 mm.

5. Step B is B.

1. Substep (200) of synthesizing a digital sweep signal s(n) by a signal generator (12); B.

2. Sub-step (210) of converting the digital sweep signal s(n) into a wideband excitation sound signal s(t) to be input to the speaker (4) via a D / A converter (13); The method of claim 3, comprising:

6. 6. The method of claim 5, wherein step D is performed via an A / D converter (15) synchronized with said D / A converter (13).

7. the calibrated frequency spectrum of the admittance [Equation 18] The method according to any one of claims 1 to 6, wherein the value of the image is further input (295) to a display (16) to be displayed.

8. The impedance probe (1) and the ear canal (6) are coupled to a first coupling arrangement (Q1), and the excitation sound signal s(t) is applied for a time period less than 1 second. [Equation 19] A fast sweep signal s whose frequency varies over ｆａｓｔ (t), and the first calibrated admittance [Equation 20] and the step further comprises: M. The calibrated admittance [0000] is satisfied, thereby obtaining the first calibrated admittance [Equation 22] and an additional step in which the peaks of the modules of correspond to the zero crossings of that phase, If a resonance condition does not occur, another iteration of the procedure consisting of steps A to M is performed, in which the impedance probe (1) and the ear canal (6) are coupled in another coupling configuration (Q2) different from the previous coupling configuration (Q1), and the excitation sound signal s(t) is coupled to a fast sweep signal s ｆａｓｔ (t), If a resonance condition occurs, steps B to L of the procedure are performed, the coupling configuration is a configuration for which a resonance condition occurs, and the excitation sound signal s(t) is a fast sweep signal s ｆａｓｔ (t) the time [Equation 23] and the one or more iterations of the procedure are terminated. The method according to any one of claims 1 to 7.

9. A device (100) for implementing a method for determining the admittance of an auditory canal (6) according to any one of claims 1 to 7, comprising: An impedance probe (1) configured for coupling with an ear canal (6), a box-like body (2) having a first end (3) adapted to be coupled to said ear canal (6); a speaker (4) located near a second end (5) of the box-like body (2) opposite the first end (3) and configured to emit an excitation sound signal (6), the speaker (4) being arranged such that the box-like body (2) is sealed to contain an air volume V at atmospheric pressure; ｐｒｏｂｅ a speaker (4) contained within the a microphone array (8) housed inside the box-like body (2) and configured to detect a return signal from the ear canal (6), the distance Δx depending on the frequency of the excitation sound signal s(t); １２ a microphone array (8) comprising at least a first microphone (9) and at least a second microphone (10) positioned between the first microphone (9) and the second microphone (10), each configured to directly detect a return acoustic pressure p(x,t) as a function of time t and output an electrical signal r(x,t); an impedance probe (1) having a control and processing device (11) configured to control and process the input and output signals of said impedance probe (1) and to carry out steps B to L, a generating unit (12) configured to generate a digital signal s(n) and transmit it to the speaker (4) via a D / A converter board (13) detachably coupled to the speaker (4); an acquisition sound board (14) configured to acquire output signals from the microphone array (8) via an A / D conversion board (15) detachably coupled to said microphone array (8); a control and processing device (11) having An apparatus (100) comprising: The apparatus (100) comprises the impedance probe (1) and the control and processing device (11) removably coupled therebetween.

10. The apparatus (100) according to claim 9, wherein the control and processing device (11) is further configured to perform step M in order to implement the method for determining the admittance of the auditory canal (6) according to claim 8.

11. 11. The device (100) according to claim 9 or 10, wherein the box-like body (2) is hollow cylindrical in shape.

12. The device is configured to input a wideband excitation sound signal s(t) in a frequency range between 100 Hz and 5000 Hz, and the distance Δx １２ The device (100) according to any one of claims 9 to 11, wherein is equal to 12 mm.

13. The device (100) according to any one of claims 9 to 12, wherein the first end (3) comprises an adapter (7) configured to obtain an easy connection with the ear canal (6).

14. 14. The device (100) according to claim 13, wherein the adapter (7) is frusto-conical in shape.

15. The device (100) described in Claim 13, wherein the adapter (7) is detachable.

16. The device (100) described in Claim 14, wherein the adapter (7) is made of rubber latex.

17. The method of claim 3, wherein the time T sweep is equal to 2 seconds.

18. The method of claim 3, wherein the time T sweep is equal to 1 second.

19. The method described in claim 3, wherein the sweep signal is a linear sinusoidal signal.

20. The method described in claim 3, wherein the sweep signal is a logarithmic sine wave signal.

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