Surgery – Diagnostic testing – Ear or testing by auditory stimulus
Patent
1998-11-09
2000-09-26
Hindenburg, Max
Surgery
Diagnostic testing
Ear or testing by auditory stimulus
A61B 500
Patent
active
061236772
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The invention relates to a method for obtaining data on hearing capacity by measuring distortion products of otoacoustic emissions, i.e. by so-called DPOAE measurement.
BACKGROUND OF THE INVENTION
It is popular opinion that the hearing capacity of man representative of vertebrates and, more particularly of mammals, is associated with active amplification processes in the internal ear which, as a whole, improve the sensitivity and frequency resolution of the ear, it being so-called otoacoustical emissions that are viewed as being the epiphenomenon of such processes. These are sound signals emitted by the ear capable of occurring spontaneously or being prompted by external stimulation, i.e. evoked, whereby the stimulation may occur, for example, acoustically or electrically.
The basic significance of evoked otoacoustical emissions for obtaining data as to hearing capacity has been known for a long time. Thus, it is described by Kemp in EP-B1-15258 that sound emissions as a reaction to a sound event can be measured in the outer auditory meatus which relate to the condition in the ear, whereby the otoacoustic emissions were measured by Kemp with the aid of an acoustical probe consisting of a highly-sensitive miniature microphone and a sound transmitter.
It is further known to determine the distortion products of otoacoustical emissions resulting from bitonal stimulation of the hearing organ, the cochlea in man, with two pure tones, so-called primary tones whereby sound emissions occur with the frequencies nf.sub.1 +mf.sub.2 having the whole numbers n and m. In man it is particularly the so-called cubic distortion product of 2f.sub.1 -f.sub.2 that permits good measurement. However, determining such DPOAE exhibits no good correlation between the amplitude of the distortion product and conventionally measured values for the hearing threshold.
By adding a third stimulus tone as the so-called disturbance tone or suppressor the DPOAE amplitude can be influenced. It is from such measurements that the conclusion arrived at in prior art was that the DPOAE amplitude can be influenced by a suppression tone in the range of the two primary tones, whereas a suppression tone close to the frequency of the distortion product has no influence on the DPOAE amplitude. In this context reference is made to the publication of Plinkert, Harris and Probst in HNO (1993) 41: 339-344 as prior art.
All attempts to date in the field of measuring otoacoustical emissions and distortion products of otoacoustical emissions have in the end the object of providing a method for objectively measuring the hearing capacity. Such a method is thus of great significance because, for example, the (subjective) indications of a human proband as a reaction to the stimulus are no longer required and measurements on all the various hearing organs can be compared to each other.
SUMMARY OF THE INVENTION
The object of the invention is thus to develop such an objective method for measuring the hearing capacity or a method meeting these requirements in the main whilst obviating the cited disadvantages, it also being the intention to develop such a method with an end to providing a corresponding device as well as a probe suitable therefor.
As the stimuli in the method in accordance with the invention two primary tones having the frequencies f.sub.1 and f.sub.2 >f.sub.1 and the sound pressure levels L.sub.1 and L.sub.2 as well as at least one sound event having components of the frequency f.sub.3 and the sound pressure level L.sub.3 are applied to the hearing organ and a distortion product of a defined frequency determined, whereby the frequency f.sub.3 has a value close to the frequency of the distortion product.
By this method it is achieved, among other things, that the dependency of the emission amplitude of the distortion product on the frequency of the stimuli can be simply determined in comparison. Producing the measurement data of the emission amplitude of the distortion product as a function of the frequency of the stimuli as a so
REFERENCES:
patent: 4007731 (1977-02-01), Griffiths et al.
patent: 4079198 (1978-03-01), Bennett
patent: 4374526 (1983-02-01), Kemp
patent: 4390748 (1983-06-01), Zwicker
patent: 5413114 (1995-05-01), Zurek et al.
patent: 5601091 (1997-02-01), Dolphin
Mitteilung aus dem Institut fur Elektroakustic der Technischen Hochschule Munchen, vol. 20, 1968, pp. 206-209 "Der Kubische Differenzton und die Erregung des Gehors", von E. Zwicker.
I INO(1993) 41:339-344, "Der Elinsatz akustischer Distorsionprodukte zur klinischen Diagnostik" by P.K. Plinkeert et al.
J. Acoust. Soc. Am. 77(2), Feb. 1985, "Specification of the acoustical input to the ear at high frequencies" pp. 577-589, S.M. Khanna et al.
IEEE Transactions on Biomedical Engineering, vol. 40, No. 5, May 1993, "Evoked Otoacoustic Emissions, Nonlinearities and Response Interpretation", P. Ravazzani et al.
Hearing Research, Bd. 86, Nr. 1-2, Jun. 1995, DIE Niederlande, Seiten 47-62, Kettembeil et al. "Distortion-product otoacoustic emissions and their anaesthesia sensitivity in the European Starling and the chicken".
Heitmann Juergen
Waldmann Bernd
Heitmann Juergen
Hindenburg Max
Plinkert Peter K.
Schnitzler Hans-Ulrich
Szmal Brian
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