Classifications

• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
  • A61B5/00—Measuring for diagnostic purposes; Identification of persons
  • A61B5/12—Audiometering
  • A61B5/121—Audiometering evaluating hearing capacity
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
  • A61B5/00—Measuring for diagnostic purposes; Identification of persons
  • A61B5/24—Detecting, measuring or recording bioelectric or biomagnetic signals of the body or parts thereof
  • A61B5/316—Modalities, i.e. specific diagnostic methods
  • A61B5/369—Electroencephalography [EEG]
  • A61B5/377—Electroencephalography [EEG] using evoked responses
  • A61B5/38—Acoustic or auditory stimuli

Definitions

• the present invention relates generally to the field of audiometric devices . More particularly, the invention relates to a multi-mode audiometric device and auditory screening method.
• BACKGROUND OF THE INVENTION Language acquisition in infants requires a critical period of hearing capacity, which spans the frequency range of human speech.
• the critical period extends from birth to about two to three years of age. when infants typically begin to talk with some level of proficiency.
• Audiometric devices which may be usable for screening an infant ' s hearing. These existing devices generally fall into one of two categories. Devices in the first category are configured to elicit auditory evoked potentials
• AEPs which are electrical responses of cells within the auditory pathway of the brain to an acoustic stimulus.
• Such devices typically utilize the non-invasive auditory brainstem response (ABR) test for auditory screening of infants.
• An earphone provides an acoustic stimulus, specifically a brief click or toneburst, to the subject's ear.
• Electrodes attached to the subject's scalp receive auditory evoked potentials (i.e., response signal(s)) from the scalp, which are recorded as an electroencephalogram waveform. Analysis of these brainwave patterns are used to determine if the auditory system is functioning normally.
• Devices in the second category utilize the evoked otoacoustic emission (OAE) test for auditory screening.
• OAE evoked otoacoustic emission
• An earphone provides a brief acoustic stimulus to the subject's ear.
• a microphone disposed in the subject ' s ear adjacent the earphone receives an OAE signal from the ear, which is recorded as an acoustic signal.
• Analysis of the OAE waveform provides an indication of the functional integrity of the middle and inner ear, which together comprise the auditory periphery.
• One limitation is that virtually all of the existing devices are complicated and require extensive training to operate.
• Another limitation is that the separate devices are required to perform ABR and OAE tests.
• Yet another limitation is that response signals are susceptible to undesirable artifact components and/or noise, which can emanate from the device itself or the subject (e.g., swallowing, grinding of teeth).
• the multi-mode audiometric device in accordance with this invention comprises stimulus generating means for transmitting at least one true random stimulus sequence to a subject ' s inner ear; first detection means for detecting at least one AEP signal, the AEP signal having at least a first waveform; second detection means for detecting at least one OAE signal, the OAE signal having at least a second waveform; signal analyzer means for analyzing the AEP and OAE signals, the signal analyzer means including first averager means for reconstructing the first waveform and second averager means for reconstructing the second waveform; and synchronization means for synchronizing the stimulus generating means and the signal analyzer means.
• the method of testing the hearing of a subject in accordance with the invention comprises (i) presenting at least one true random stimulus sequence to said subject's inner ear, (ii) detecting at least one AEP signal, the AEP signal having at least a first waveform, the first waveform including a first set of AEP signal data, (iii) detecting at least one OAE signal, the OAE signal having at least a second waveform, the second waveform including a first set of OAE signal data, (iv) recording the AEP and OAE signals, (v) sampling the first set of AEP signal data by applying a plurality of true random frequencies to the first set of AEP signal data to provide at least a second set of AEP signal data, (vi) recording the second set of AEP signal data, (vii) reconstructing the first waveform from the second set of AEP signal data, and (viii) averaging the first set of OAE signal data to reconstruct the second waveform.
• FIGURE 1 is a schematic illustration of the multi-mode audiometric device according to the invention.
• FIGURE 2 is a block diagram of the multi-mode audiometric device according to the invention. DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
• the present invention substantially reduces or eliminates the disadvantages and drawbacks of prior art audiometric screening devices and methods.
• the multi-mode audiometric screening device of the invention provides a fully automated screening procedure which includes stimulus presentation, multiple response signal acquisition, multiple signal analysis, and interpretation and display of results.
• FIG. 1 there is shown a preferred portable multi-mode audiometric screening system 20 incorporating the principals of the invention.
• the system
• a laptop computer 22 having control means 30 adapted to control the audiometric screening process, signal processing means 40 adapted to provide the unique "true random” stimulus signals and analyze the response signals emanating from the (infant) subject 10, and memory means 50 adapted to store pertinent data and information (see Fig. 2).
• the audiometric screening system 20 further includes a probe 24 having an earphone 26 for presenting the acoustic stimulus signals generated by the signal processing means 40 to the subject 10.
• the earphone 26 also receives the OAE response signal from the subject's ear 12.
• the audiometric screening system 20 also includes a plurality of electrodes 28 that are operatively attached to the subject ' s scalp. According to the invention, the electrodes 28 sense and communicate the AEP or response signal to the signal processing means 40 of the invention.
• one or more characteristics of the processed signals are displayed on the computer monitor 23.
• other pertinent information stored in the memory means 50 and/or provided by the signal processing means 40 is also displayed on the monitor 23.
• the laptop computer 22 preferably includes three primary components or systems: control means 30, signal processing means 40 and memory means 50.
• the key component of the system 20 is, however, the signal processing means 40.
• the signal processing means 40 includes two subsystems: signal generator means 42 and signal analyzer means 42.
• the signal generator means 42 provides a continuous, "true random " sequence - varying stimuli frequency and rate - that is presented to the subject via probe 24. As discussed in detail in Co-Pending Application No.
• the "true random” sequence substantially reduces or eliminates “synchronous artifacts.”
• the "true random” sequence is preferably presented to the subject in the form of clicks or pulses - wide bandwidth, deterministic, short-duration signals.
• the signal duration is typically limited by the duration of the impulse response of the acoustic source transducer, since the electrical input signal to the source transducer is typically much shorter than the impulse response duration.
• the stimulus duration is generally in the range of 80-100 msec, whereas the overall duration of the click-evoked otoacoustic emission (CEOAE) response is in the range of 10-40 msec.
• CEOAE click-evoked otoacoustic emission
• ABR testing thus typically employs a stimulus rate in the range of 35 to 40 Hz (e.g., 37 clicks/sec).
• a stimulus rate in the range of 35 to 40 Hz (e.g., 37 clicks/sec).
• the stimulus rate is in the range of 30 to 300, preferably 100 to 200 clicks/sec.
• the variation in stimulus rate is also preferably maintained in the range of +/- 10 to 50 %. More preferably, the variation in stimulus rate is maintained in the range of +/- 30 to 50 %.
• the signal analyzer means 44 includes a plurality of signal sampling techniques and signal processing algorithms.
• a "true random” sampling technique is employed to analyze and, hence, determine the waveform of the AEP signal resulting from the "true random” stimulus. Details of the "true random” sampling technique are similarly set forth in Co-Pending Application S/N (Docket No. PCL-02-002U), filed
• the signal analyzer means 44 also includes first averager means to read the spectral waveform that is produced by the noted random sampling technique.
• the first averager means comprises the
• the "true random” sampling technique provides a reconstructed waveform that physiologically occurs in time intervals that are representative of the "actual" data emanating from the subject, without contamination from any extraneous, synchronous sources.
• the acoustic response comprises two distinct, "time-spaced” (i.e., synchronous) components, (i) a direct signal component and (ii) an echo signal component.
• the direct signal component represents the response of the ear drum and the middle ear, which typically terminates approximately 5 msec, after presentation of the stimulus.
• the echo signal component which is more closely related to the characteristics and condition of the inner ear, typically terminates approximately 15 msec, thereafter.
• the signal analyzer means 44 further includes synchronization means for synchronizing the signal generator means 42 and signal processing means 40. Since the noted OAE signal components are "time-spaced", but in synchrony, the echo signal component is readily separated and identified by the synchronization means. The echo signal component is then stored in the memory means 50 of the invention.
• the signal analyzer means 42 additionally includes second averager means for reconstructing the OAE waveform.
• the second averager means is preferably adapted to be responsive to a sequence of 20-2000 echoes.
• the second averager means can comprise various conventional averagers and associated algorithms, such as the averager and associated ensemble averaging and group variance techniques disclosed in U.S. Pat. No.
• the second averager means comprises a "true random" sequence deconvolution technique.
• the AEP acquired from the subject 10 the data provided via the "true random” sampling technique and the reconstructed waveform determined therefrom, and the averaged OAE signal are stored in the memory means 50 of the system 20 for subsequent, separate analysis, if desired, and visual display on the monitor 23 for assessment.
• control means 30 are provided.
• the control means 20 comprises a micro-processor adapted to be programmed to perform a plurality of discreet and inter-related functions, including (i) control of the presentation of the stimuli, (ii) acquisition, processing and analysis of the noted response signals, (iii) input and extraction of information and data to/from the memory means 50 and (iv) display of desired information and/or data on the computer display 23.
• the control means are also adapted to be responsive to multiple user commands, including entry and storage of subject data and testing parameters.
• the noted control means 50 can also be programmed to perform numerous additional functions independently and in response to user commands.
• the above described multi- mode audiometric device and screening method provides numerous advantages over prior art devices and methods.
• the advantages include:

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• Health & Medical Sciences (AREA)
• Life Sciences & Earth Sciences (AREA)
• Audiology, Speech & Language Pathology (AREA)
• Physics & Mathematics (AREA)
• Engineering & Computer Science (AREA)
• Biomedical Technology (AREA)
• Medical Informatics (AREA)
• Acoustics & Sound (AREA)
• Biophysics (AREA)
• Pathology (AREA)
• Otolaryngology (AREA)
• Heart & Thoracic Surgery (AREA)
• Multimedia (AREA)
• Molecular Biology (AREA)
• Surgery (AREA)
• Animal Behavior & Ethology (AREA)
• General Health & Medical Sciences (AREA)
• Public Health (AREA)
• Veterinary Medicine (AREA)
• Measurement Of The Respiration, Hearing Ability, Form, And Blood Characteristics Of Living Organisms (AREA)

Priority Applications (3)

Applications Claiming Priority (4)

Publications (2)

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• 2001
  • 2001-02-13 WO PCT/US2001/004579 patent/WO2001060231A2/en not_active Ceased
  • 2001-02-13 EP EP01910605A patent/EP1257193A4/en not_active Withdrawn
  • 2001-02-13 JP JP2001559332A patent/JP3612303B2/ja not_active Expired - Fee Related
  • 2001-02-13 US US09/782,771 patent/US6503207B2/en not_active Expired - Lifetime
  • 2001-02-13 AU AU2001238196A patent/AU2001238196A1/en not_active Abandoned

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