ES2858150A1 - HEARING MEASUREMENT METHOD AND SYSTEM AND DEVICE THAT UNDERSTANDS IT (Machine-translation by Google Translate, not legally binding) - Google Patents

Abstract

Auditory measurement method and system. The hearing health measurement method involves performing a predefined sequence of instructions or steps. A first step to emit, in at least one ear, a sound signal of variable intensity over time and of a frequency belonging to a selection of frequencies from the spectrum audible by the human being. A step to record, in response to a user perception indication or continuously, the intensity of the sound signal. A step to emit, during a first interval, a pulse of the sound signal with a known intensity and frequency. A step to acquire the intensity of the sound signal corresponding to the echo and its attenuation during a second interval. A step to compare both the recorded signal strength and the echo strength and attenuation with a range of values and establish if there is a significant deviation. (Machine-translation by Google Translate, not legally binding)

Description

HEARING MEASUREMENT METHOD AND SYSTEM AND DEVICE THAT

UNDERSTANDS

Technical field of the invention

The present invention belongs to the field of audiology, in particular to techniques applicable to a wearable device.

State of the art

At present, the detection of auditory pathologies and the evaluation of the functioning of the middle ear implies the intervention of the otolaryngologist and specific medical devices. In clinical practice, there are mainly two hearing tests to perform this evaluation: tympanometry and audiometry.

Tympanometry is a test used to analyze the transmission of sound through the middle ear. By means of air pressure gradients in the ear canal, the mobility and rigidity of the eardrum (tympanic membrane) and the conductive ossicles present in the middle ear can be determined. It should not be used to evaluate the sensitivity of the ear.

This technique is performed through a device known as a tympanometer. The tympanometer is made up of a loudspeaker, a microphone and a pressure pump that allows the pressure gradient of the air to be changed. In this way, the device applies pressure differences to the patient's ear while emitting sound signals of known frequency and intensity, the echo of which is picked up by the microphone to construct the tympanogram. The sound signal consists of a constant low-frequency tone emitted through the speaker. The echo consists of the sound signal reflected by the middle ear canal and the tympanic membrane. The tympanometer requires maintenance to be properly calibrated and to ensure that it emits at standardized frequencies.

A low-frequency tone is used because the behavior of the middle ear canal, formed by the eardrum and the ossicular chain, is dominated by rigidity. The tympanic membrane present is usually rigid. However, when the air pressure is similar on both sides of the eardrum, it becomes more flexible. The ossicles of the middle ear are small and therefore do not have much mass. Thus, stiffness is the main source of opposition to the passage of sound through the middle ear. Stiffness opposes the passage of low frequencies and resonates at high frequencies, while mass opposes the passage of high frequencies and resonates at low frequencies. In this way, it is ensured that a small amount of sound is reflected from the tympanic membrane, even when the middle ear is not highly rigid.

On the other hand, the other test to assess hearing function is audiometry, which assesses the ear's ability to perceive vibrations at various frequencies of the audible spectrum. The most widely used is subjective pure tone (frequency) audiometry. It is a standardized test that consists of the analysis of a frequency band between 125 and 8000 Hz. The unit of intensity used in audiometry is the decibel of sound pressure level (dB SPL).

The device used is called an audiometer. The audiometer electronically generates the sound signals at frequencies with precise values in an acoustic transducer, for example, a headphone or a loudspeaker. If the evaluated subject detects the tones or other stimuli, it indicates it by pressing a button or push-button. Audiometers need maintenance to be properly calibrated and to ensure that they emit at standardized frequencies.

Both tests require a specialist. This implies several drawbacks. The first of all is face-to-face assistance to a consultation or clinic to perform the tests, with the consequent collapse of the medical centers specialized in otorhinolaryngology (ENT). This collapse could be avoided if these tests were done automatically and remotely. The next drawback or limitation is the price, since these equipment must have the CE sanitary certificate and therefore are usually expensive to design, develop and certify, a fact that has its consequence in the final price. Being so reliable and robust, these devices are usually heavy and not very portable equipment, this being the main reason why people should go to the mentioned ENT consultations. The calibration and maintenance of this equipment is also a limitation derived from its precision. Calibration processes have to be done with very expensive devices and the process is very complex. Finally, when a report is required for a diagnosis, a requires a suite of complementary tests to obtain clinically reliable results.

Brief description of the invention

Among the objectives of the present invention is the estimation of hearing quality without measuring the pressure difference between the environment and the interior of the tympanic membrane. In this way, the intervention of a specialist is not necessary. The test is more comfortable and without the need for expensive devices. Consequently, the invention is capable of being implemented in any type of personal protective equipment, being a consumer electronics wearable , or it can itself constitute a new generation of medical equipment that favors telecare in ENT.

A method, a system and a storage medium are proposed according to the independent claims. Particular embodiments of the invention are defined in the dependent claims. The storage medium stores readable instructions on any medium, such as an SSD memory, a CD, DVD, ROM memory, etc. When these instructions are executed in a processor (or processors) of a computer, they carry out the steps of the proposed method.

Brief description of the figures

To complement the description that is being made and in order to help a better understanding of the characteristics of the invention, a set of drawings is attached as an integral part of said description, in which, with an illustrative and non-limiting nature, the following has been represented. following:

FIG. 1: Schematic of the state-of-the-art tympanometer probe.

FIG. 2: Examples of different types of tympanograms.

FIG. 3: Examples of hearing loss and non-hearing loss audiogram.

FIG. 4: Representation of the sound signals used.

FIG. 5: Step diagram for an example method.

FIG. 6: Block and component diagram for an example system.

Detailed description of the invention

FIG. 1 shows a schematic of a typical tympanometer used in a clinical setting, where its components can be identified. The figure shows a 226 Hz tone generator 23, a microphone 5, and an air pump 21 with a pressure gauge 22.

FIG. 2 shows a conventional tympanogram with its characteristic tent-like shape (type A curve). The horizontal axis shows the negative, neutral and positive air pressure gradients. The units of air pressure on the horizontal axis are mm H2O or decapascals (daPa). These pressure units have a similar absolute value on either side of the air pressure gradient null value.

The vertical axis shows admittance or compliance. Admittance is measured in milliliters (ml) or cubic centimeters (cc) of air. It is an inverse magnitude of stiffness and is defined as the mobility or elasticity of the ear referring to the ease of transmission of sound through it. Another common unit to refer to admittance is the mho (inverse unit of resistance measurement: ohm).

Identifying whether there is a variation in admittance provides information on how sound is conducted in the middle ear canal. From this functional evaluation, hearing problems can be detected.

Generally, the low-frequency tone used in tympanometry has a specific frequency of 226 Hz. This is done primarily for calibration reasons. At a regular air pressure at sea level, the admittance of 1 cc of air at a pitch of 226 Hz is exactly one mmho.

From the graph in FIG. 2, it is concluded that the middle auditory canal transmits the acoustic signal more efficiently when the pressure is equal on both sides of the eardrum. When the microphone picks up a lower level of sound signal, it is understood that most of the signal is passing through the ear canal, this is the interval that contains the peak (point H), in which the air pressure behind the membrane is same as external channel. When the microphone picks up a greater amount of signal (points L and L '), it is because a greater part of it has been reflected by the tympanic membrane.

This circumstance is more common the greater the pressure difference on both sides of the eardrum.

Also in FIG. 2 shows the different types of tympanograms that can be found regularly. The type A curve corresponds to normal hearing, while the type B and type C curves are related to different pathological processes. The type B curve corresponds to a very relevant rise in impedance. This high impedance value can be caused by the presence of fluid, earwax, or by some type of otitis, among other possible pathologies or even by the existence of a tympanic perforation. In the type C curve, the admittance point is displaced at very negative pressures, a circumstance that is common in situations of permanent depression of the middle ear that result in a malfunction of the tube.

These curves A, B and C are especially useful since three main types can be considered from which any other curve can be expressed as a variant, for example, because it has intermediate or combined characteristics.

Tympanometry characterizes the physical properties of the middle ear, through the reflectance of a 226 Hz tone with changes in air pressure. The goal is to identify its stiffness (or admittance) per se. If a tympanogram such as those exemplified in FIG. 2, it is seen how the admittance value would vary enormously between subjects. This is because different probe insertion depths change the volume of the ear canal in any person. Also, ear canals vary in size between different people. Therefore, what really matters is the geometry of the function and not so much its absolute values.

Measurement of admittance in units of mmhos provides tympanograms of similar size regardless of probe insertion depth or ear canal size. Allows a preset range of tympanogram size and shape to be used as normative or standard. Changes in dB SPL that are reflected from the tympanic membrane correspond to changes in admittance; the less sound is reflected, the higher the admittance.

On the other hand, FIG. 3 illustrates the example of two audiograms, one corresponding to a patient with loss (dashed line) and the other without hearing loss (solid line). By analyzing each ear separately, both the air conduction pathway like bone, obtaining data from the hearing threshold. This test is based on a different principle than the tympanometry test, since headphones cannot produce pressure changes in the inner ear by not incorporating a pressure pump.

This proposal does not measure pressure changes. It assumes that there is an unknown pressure difference between atmospheric or surrounding pressure and the pressure inside the tympanic membrane. The proposed hearing measurement technique will emit various tones at different points in the audible spectrum. With which the procedure would be similar to performing a tympanometry in each of the frequency points that the audiogram constructs. For each significant frequency point (as in audiometry), a tone is emitted that allows the hearing threshold to be measured, but the reflected echo is also collected. Therefore, the amount of sound that is transmitted through the auditory system is known (as in tympanometry). The value obtained by the microphone in charge of collecting the echo at each of these frequencies must be kept constant during the measurements taken on the same user, unless it is affected by some pathology and therefore presents abnormal oscillations.

FIG. 4 illustrates the intensity of the sound signals registered by the microphone when carrying out the methodology proposed in the invention. The human audible frequency spectrum ranges from 20Hz to 20kHz. Generally, it is sufficient to choose six to eight values from this audible frequency spectrum for your functional evaluation. As a practical example, the audiogram is constructed with tests at the frequencies of 250Hz, 500Hz, 1kHz, 2kHz, 4kHz and 8kHz. In the methodology proposed in the invention, the device performs a test for each point in frequency chosen in each ear.

In particular, as exemplified in the graph of FIG. 4, the sound signal is picked up by the device as a function of time along different sections following a sequence of steps:

• Section 1: During a minimum interval of 0.5s, the initial noise intensity is obtained, which we will call the first basal noise component. Basal noise is understood as the intensity of the environmental signal present at the time of acquisition. In this way, the basal noise will act as an offset for the collected signal.

• T branch 2: A tone begins to be emitted at a known frequency with zero intensity and the intensity (volume) of the tone is progressively and linearly increased (although it can be staggered with various intensity levels) until the user can perceive sound. At that moment, the device picks up the reflection of this emitted signal. Section 2 ends when the user indicates that they perceive the sound (through its interaction with an associated button). In this way the hearing threshold level is identified.

• Segment 3: This is a minimum interval of 0.5s with zero signal intensity to obtain the second baseline noise component. The baseline noise level is rechecked for evidence that it has not changed and remains at the same level throughout the test. In this way, it is verified that the test is not compromised by any unexpected acoustic interference.

• Section 4: It is a 0.1s interval where the same tone is emitted again and with the minimum intensity previously perceived by the user.

• Section 5: This is a minimum interval of 0.75s whose objective is to collect the attenuation of the reflected echo until reaching the basal noise level. It is used to capture the mechanical response of the ear. No tone is emitted at this stage. By mechanical response is understood the movement (dependent on its stiffness) of the tympanic membrane as a consequence of the energy transmitted by the acoustic signal.

Subsequently, the same test is carried out at the next frequency of interest and so on. DB SPL ranges, amplitudes of echo signals, RMS values of basal levels, and duration times of each sub-span and characteristic are compared.

As the next step to quantitatively characterize this mechanical response of the middle ear canal, a post-processing of the acquired signal is implemented by means of an analysis in the time-frequency domain to eliminate the noise components of the echo of each emitted pulse. Next, a statistical analysis of the most relevant parameters of the signal is carried out to conclude the characterization of the user's auditory response.

Through this proposal, the admittance present in the user's middle ear can be determined, in order to estimate their hearing health. To do this, the values mentioned above are taken to characterize the behavior of the system. auditory. It is known that the acquired values are admittances at different frequencies and that they should be constant values over time, indicating that the behavior of the system does not change.

Faced with a significant variation or oscillation of these values in any of the acquisitions, it is understood that there is a different behavior in the ear. Being a system dominated by stiffness, a significantly different response indicates a change in the pressure of some component that is given by a predictably pathological origin. By continually monitoring these admittances, hearing dysfunctions can be identified early.

The proposed technique does not obtain the exact vertical of the X axis of the tympanogram (see FIG.

2) where the user is (pressure difference) and therefore the point on the tympanometry curve that the headset is acquiring is unknown. However, once this parameter has been collected, monitored, analyzed over time, and knowing the literature and the principles of the test, it is known that a significant change in the acquired parameter implies a change in pressure in the middle ear that can be caused pathological origin. A significant change is defined by the presence of a similar effect in each of the frequencies that are analyzed. The significance of these changes can be supported by statistical evidence.

In this way, control over a parameter of hearing quality, similar to admittance, can be established through common components implemented as a system that can be integrated into portable devices for the population.

In FIG. 5 schematically illustrates a diagram of the method according to the invention with the sequence of the main steps carried out. It can be seen that there is a step 31 of initial sound emission with intensity variable in time and with a frequency in the audible spectrum. A first check 41 is made to check the perception of the pulse by the user. If not, go to step 36 of increasing the intensity and return to step 31. If the first check 41 is affirmative, the method continues with a step 32 of recording the intensity of the sound signal followed by a step 33 emission of a pulse with known intensity and frequency. Subsequently, a step 34 is performed to acquire the intensity of the sound signal corresponding to the echo and its attenuation during a second interval. This leads to a second check 42 to check the completion of the frequencies of interest for the pulses. If not, continue with a step 35 of increasing the frequency. In the affirmative case, that is, if there are no more frequencies of interest, a third check 43 is carried out to compare both the recorded signal intensity, the echo intensity and the attenuation with respect to the set of values acquired over time for the same Username. Thus, it is possible to establish whether there is a significant deviation in the acquired values.

In FIG. 6 illustrates a functional block diagram corresponding to an embodiment of the measurement system that carries out the sequence of steps and sections indicated in FIG. 4. This system can be implemented as a wearable device by the user. A processor 1 can be seen that is responsible for locally controlling various components. An interface 4 collects the indications of the user when he perceives the sound signal emitted. The characteristics of the perceived sound signal are stored in a memory 8. This sound signal is preferably emitted by a pair of headphones 2, 3 for the left and right ear. The processor 1 produces the signals of a given frequency and with increasing intensity in an earphone 2, 3 in a first phase. After applying a time-out interval, the same sound signal that was perceived by the user in the corresponding handset 2, 3 is repeated. By means of the microphone 5, 6 embedded in each earphone 2, 3 the sound signal corresponding to the attenuation and echo of the signal previously emitted in each earphone 2, 3 is captured. A third microphone 7 is in charge of measuring the ambient noise (basal ) in case its level is excessive and could affect the conclusions. The signals captured by the microphones 5, 6 are recorded and stored in memory 8.

The interface 4 may include a first button, intended to start the test to determine admittance, a second button, to indicate that the user is listening to the tones emitted at the different frequencies.

It is possible to have a server 10 to externally perform additional processing when it is complex. Therefore, the system can incorporate a communication unit 9 with which to exchange information between the processor 1 and the server 10. For example, data related to the deviation obtained after the comparison. Preferably, this communication unit 9 is integrated into the system and uses wireless technology.

The server 10 can behave as a master device for remote control of the microphones 5, 6 and / or the headphones 2, 3 included in the system through the communications unit 9, unloading tasks to the processor 1.

The invention can be integrated into different portable devices, for example in headphones connected to an audio player. In this case, it can be equipped with new features, such as personalized volume control automatically based on outside noise and the user's hearing health. In this way, the playback volume will be adjusted according to the external noise level and the user's hearing status to always seek the best listening quality.

Additionally, a volume correspondence can be established at permitted levels according to the level of ambient noise captured by the third microphone 7. It can be said that it is a way of controlling the abusive use that is sometimes made of this type of playback devices. audio and thus be able to prolong hearing health for longer.

NUMERICAL REFERENCES

1 Processor.

2 Left earphone.

3 Right earphone.

4 Interface.

5 Microphone embedded in left earphone.

6 Microphone embedded in right earphone.

7 Ambient microphone.

8 Memory.

9 Communication unit.

10 Remote server.

21 Air pump.

22 Pressure gauge

23 Tone generator.

31 Initial sound emission step.

32 Intensity recording step.

33 Step of emission of a pulse.

34 Acquisition step of echo intensity and attenuation.

35 Frequency increase step.

36 Step of intensity increase.

41 Pulse perception check step.

42 Step of checking the completion of frequencies of interest for the pulses.

43 Check step to compare recorded signal strength, echo and attenuation.

Claims (14)

1. Auditory measurement method for a user who understands performing the following steps: emitting, in at least one of the ears, a sound signal of variable intensity in time and of a frequency belonging to a selection of frequencies of the spectrum audible by the human being; recording, in response to a user perception indication or continuously, the intensity of the sound signal; emitting, during a first interval, a pulse of the sound signal with a known intensity and frequency; acquire the intensity of the sound signal corresponding to the echo and its attenuation during a second interval; compare both the recorded signal strength and the echo strength and attenuation with a range of values and establish if there is a significant deviation. A hearing measurement method according to claim 1, further comprising applying a zero intensity wait interval for the sound signal and recording the basal noise intensity after the step of recording the user perceived sound intensity. Auditory measurement method according to claim 1 or 2, further comprising re-acquiring and evaluating the intensity of the ambient sound signal corresponding to the outside during a third interval. Hearing measurement method according to claim 3, wherein the intensity of the environmental sound signal modifies the establishment of the significant deviation corresponding to a pathology. Auditory measurement method according to any one of the preceding claims, where: the first interval is a value in the range [0.05, 0.3] s; the waiting interval is in the range [0.3, 0.7] s; and the second acquisition interval are between [0.7, 1] s. 6. Auditory measurement system for a user that includes: a processor (1); a memory (8); an acoustic transducer; a microphone (5,6); characterized in that the processor (1) is configured to: emitting, in at least one of the ears through an acoustic transducer, a sound signal with a variable intensity over time and with a frequency belonging to a selection of frequencies from the spectrum audible by the human being; recording, in memory (8), in response to a user perception indication or continuously, the intensity of the sound signal; emitting, through the acoustic transducer, during a first interval, a pulse of the sound signal with the value of the recorded recognizable intensity; acquiring, through a microphone (5, 6), the intensity of the sound signal corresponding to the echo and its attenuation during a second interval; compare both the recorded recognizable intensity and the echo intensity and attenuation with a range of values and establish if there is a significant deviation corresponding to a pathology. System according to claim 6, wherein the processor (1) is further configured to apply a waiting interval with zero intensity for the sound signal and record the basal noise intensity after the step of recording the sound intensity perceived by the user. System according to claim 6 or 7, wherein the processor (1) is further configured to acquire the intensity of the ambient sound signal corresponding to the outside during a third interval through an additional ambient microphone (7). 9. System according to any one of the preceding claims 6 to 8, wherein the acoustic transducer is an earphone (2,3). System according to any one of the preceding claims 6 to 9, wherein the interface (4) comprises a button. System according to any one of the preceding claims 6 to 10, comprising a communication unit (9) configured to communicate with a server (10) to send and receive data relating to the deviation obtained after the comparison. System according to claim 11, wherein the communication unit (9) is configured to receive control instructions from the server (10) to control the acoustic transducer and / or the microphone (5, 6). 13. Portable device comprising embedded the hearing measurement system for a user according to any one of the preceding claims 6 to 12. 14. Computer-readable storage medium that stores instructions that when executed in one or more processors carry out the method claimed in any one of claims 1 to 5.