WO2008129083A1

WO2008129083A1 - Apparatus for processing the bioelectric signal obtained as response to an auditory stimulus and method for processing of said signal by said apparatus

Info

Publication number: WO2008129083A1
Application number: PCT/ES2007/070079
Authority: WO
Inventors: Julio Sanjuan Juaristi
Original assignee: Julio Sanjuan Juaristi
Priority date: 2007-04-19
Filing date: 2007-04-19
Publication date: 2008-10-30

Abstract

Apparatus for processing the the bioelectric signal obtained as a response to an auditory stimulus and method for processing said signal by said apparatus. The apparatus comprises a pure tone generator with a characteristic trigger signal in each wave cycle and a receiver equipped with a set of bioelectric sensors, at least one differential amplifier with a band-pass filter in the range to be studied, at least one frequency filter, wherein the signals outside the target range are eliminated; and an information management device, for use in correlating and storing the signals received.

Description

Apparatus for the treatment of the bioelectric signal obtained in response to an auditory stimulus and method of treatment of said signal by said apparatus.

The present invention has as an apparatus for the treatment of the bioelectric signal obtained in response to a sound stimulus that includes an emitter of an external acoustic signal, and a receiver of the bioelectric response by means of electrodes that are disposed in the skin of the a patient as well as frequency filters ..

The present invention also comprises a method for the treatment of said bioelectric signal carried out by said apparatus, which allows obtaining a direct correlation between the signal emitted as a stimulus and the one received as a biological response, from which its response level can be inferred .

The detection of hearing impairments has been a problem throughout history, particularly when trying to detect these problems in young children, who are not able to tell when they hear a signal and when they do not. In addition, in the case of adults, in conventional systems in which the ear is stimulated with a variable acoustic signal in frequency and intensity, it is the patient who must indicate at what time he hears and at which time he does not. This results in a subjectivity, since the feeling of hearing has a diffuse threshold and depends not only on the physical condition of the person, but also on subjective criteria. Some people will say that they hear when they seem to start hearing, and others when the hearing is clearly perceived. In addition, in some cases, especially in newborn children it is not possible to seek a subjective response and in those of young age, shyness may prevail, which will prevent a correct detection of the degree of hearing. Hearing problems can have different causes. The eardrum acts as a membrane that receives the sound pressure waves and its vibratory movement is transmitted through the chain of ossicles to the inner ear where the auditory receptors that transform the sound pressure into bioelectric currents are located. The primary transducers are the external hair cells implanted in the basilar membrane, which generate the cochlear microphonic potentials.

Therefore, the object of this invention is the description of an apparatus useful in the detection of the cochlear microphonic response generated in the outer hair cells.

STATE OF THE TECHNIQUE

There are different methods that are carried out for the detection of hearing impairments.

Otoemissions. It consists of the application of an acoustic signal ("click" as a stimulus)) and subsequent detection of an acoustic response as an "echo", lacking precision and reliability. If the result is negative and there is no answer or it is not in the "normal" ranges, other methods are used.

PEATC (Auditory Brain Trunk Evoked Potentials)

They detect electrical potentials at the level of the brainstem before sound stimuli as impulses of milliseconds called "click" It does not allow obtaining an audiogram, and the results are distorted by the effect of the click that is a transitory stimulus of unpredictable amplitude and component of frequencies PEE (Stable State Potentials)

Use as stimulus pure tones amplitude modulated by a very low frequency wave, you cannot register results below 500 HZ. The response is obtained at the level of cerebral tranco and doubtful audiometric deductions are made by processing the potential spike at the level of the brainstem. The result, in derived tension, would correspond to the number of potential spikes caused by cochlear microphonic potentials (PMC), which in turn depends on the state of the hair cells and the amplitude of the pure modulated tone. It is a better procedure than the PEATC with the possibility of tonotopic determination, but it is a complex way to analyze the cochlear function. The reason that its registration is carried out so far from the auditory receptor (elbow) is that at the level of the brainstem the derived potential is of the order of microvolts, while in the cochlea, for PMCs, it is nano or picovolts, becoming much more difficult the registration of the latter because of the unfavorable signal-to-noise ratio

The present invention aims at an apparatus whose function is to take exclusively the potential of the external hair cells in response to a sound stimulus corresponding to an acoustic signal of pure tones produced by the apparatus and perform a corresponding filtering of the bioelectric signal obtained which comprises at least one emitter of a sound at a predetermined frequency or frequencies, including the emitter a sequential signal generator or triguer and at least one receiver which in turn comprises:

• A set of bioelectric sensors, capable of adherently adhering to the patient's skin; • At least one differential amplifier with bandpass filter in the range to be studied;

• Frequency filters, with which the signals that are outside the range of interest are eliminated; and «An information management device, capable of interpreting the received signals.

The method of signal processing includes the processes of:

• Emission of a pure tone acoustic signal at a certain frequency and intensity; The frequency and intensity may be varied from one scan to another; said acoustic signal is accompanied by a pulse signal indicator or triguer;

• Receiving a bioelectric signal; The bioelectric signal comprises the placement in the patient's body of contact electrodes that collect the signal by sending it to an amplifying device; • Amplification of the signal, in one or more stages;

• Filtering of the detected electrical signal corresponding to the frequency of the signal emitted as a stimulus.

• Selection by computer means of the resulting electrical signal from the acoustic signal emitted with its identification by the triguer brand. • Determination of the degree of response between the acoustic emission as a stimulus and the biological signal as a response.

Brief description of the drawings In order to illustrate the explanation to be followed, three sheets of drawings are attached to the present specification, in which the object of the present invention is schematically represented in a three-figure figure, and in which:

Figure 1 shows a block diagram representing the apparatus and method of the present invention;

Figure 2 shows a graph of the primary data of the microfonites; from them, the cochlear microphone audiogram is obtained; and Figure 3 shows a cochlear microphonic audiogram and recruirment graphs obtained by the apparatus of the invention.

DETAILED DESCRIPTION OF THE INVENTION As it has been said, the present invention consists of an apparatus for the treatment of the bioelectric signal of the auditory sensory receptors, obtained in response to a sound stimulus and method of treatment of said signal by said apparatus comprising the stimulus production by means of a generator, which is a pure sinewave electrical signal with a certain frequency and intensity, both calibrated and adjustable parameters. The generator includes a transducer that converts said electrical signal into a sound to apply it to the patient under study.

In the cochlea there is the set of sensory cells (external ciliates) transducers of the received pressure wave, in microphonic potential, that is, there is a change in the sound stimulus of a mechanical nature in electrobiological potential. For example, if the emitted signal Io is at a frequency of 2000 Hz, the filters must eliminate all signals of a frequency other than said 2000 Hz.

Consequently, among the remaining signals, there are all the perturbations of the same frequency to that of the stimulus and therefore to the cochlear microphonic response. It is necessary to eliminate these disturbing potentials. For this we have the triguer pulse that is always in phase agreement only with the cochlear microphone evoked by software eliminating all those disturbances that even being of the same frequency are random in phase.

In this way, clean information can be obtained on the correlation between the stimulus issued and the response received, and obtained in real time, at the time the corresponding test is performed, and, in short, obtain an objective audiogram.

The invention is schematically represented according to a block diagram of Figure 1, in which a patient who is making the diagnosis is indicated with 1, with 7 a pure tone generator, with 9 an audio frequency signal from the generator pure tones 7 and the corresponding triguer, with 6 a transducer that transforms the audio frequency signal 9 into an acoustic signal 8, with 2 a differential prior amplifier, with 3 a set of filters of the bioelectric signal received and amplified by the amplifier 2; with 4 a processor of the filtered signal received, as well as the information corresponding to the tone generator and triguer 7, with 5 a display monitor, with 10 a printer output.

Application in auxiliary devices for medicine.

Claims

1.- Apparatus for the treatment of the bioelectric signal obtained in response to a sound stimulus characterized by comprising: «At least one generator of continuous pure tones, that is to say an emitter of a single frequency signal to be selected; together with the pure signal, the generator generates a pulse or triguer for each wave cycle emitted; and • A receiver, which in turn comprises: o A set of electrodes capable of adhering to the patient's skin; o At least one differential amplifier with bandpass filter in the range to be studied; o At least one frequency filter, in which signals that are outside the range of interest are eliminated. An information management device, capable of correlating and storing the received signals.

2.- Method of treatment of the signal emitted by the apparatus of claim 1, characterized by understanding. • Emission of at least one continuous pure tone acoustic signal at a certain frequency and intensity; The frequency and intensity may be susceptible to calibrated variation.

• Emission, of a sequential signal in each wave cycle (triguer) to perform the final cleaning process of the signal by phase synchronism. • Receiving a bioelectric signal;

• Transmission to an amplifying device; • Filtering of the electrical signal corresponding to the frequency object of the emitted signal;

• Amplification of the signal, in one or more stages;

• Selection between the disturbing frequencies of the same frequency as the resulting electrical signal from the emitted acoustic signal, depending on the triguer mark that corresponds only to the microphone power. Determination, by computer means, of the degree of response between the acoustic emission and the received signal.