Speech-like ASSR Stimulus for Hearing Aid Fitting Verification
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Solution Overview
Problem
Current methods for recording Auditory Steady State Responses (ASSR) face challenges in accurately verifying hearing aid fitting, especially in infants and hard-to-test individuals, due to the reliance on transient stimuli that are prone to distortion and variability, and the need for objective physiological measures that can assess speech processing abilities.
Innovation Solution
A method is introduced to create a speech-like ASSR stimulus with amplitude variations similar to free-running speech, using spectrally shaped multi-band stimuli with independent speech envelopes and low-frequency amplitude modulation, allowing for simultaneous estimation of electrophysiological responses at different speech levels, which can guide hearing aid gain settings and facilitate automated fitting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If transient acoustic stimuli are used to record auditory evoked potentials, then the recording can be performed with simple equipment, but the responses are prone to distortion and variability making verification of hearing aid fitting inaccurate
Solution Approach 1:
The patent uses periodic amplitude-modulated tones as auditory stimuli instead of transient sounds. The stimuli are presented as continuous tones modulated at specific rates (e.g., 80 Hz, 100 Hz) which elicit steady-state auditory evoked potentials that are more consistent and less prone to distortion, thereby improving measurement precision for hearing aid fitting verification
Solution Approach 2:
The patent employs continuous auditory stimuli rather than discrete transient presentations. The continuous amplitude-modulated tones maintain steady-state activation of the auditory pathway, producing continuous evoked potentials that can be averaged and measured with higher reliability, reducing variability in the responses
2Productivity
If multiple frequency-specific stimuli are presented simultaneously to enable multi-band ASSR recording, then the testing efficiency increases, but the stimulus complexity and difficulty of response detection increase
Solution Approach 1:
The patent divides the auditory frequency spectrum into multiple distinct bands (e.g., low-frequency, mid-frequency, high-frequency regions) and presents different amplitude-modulated tones simultaneously in each band. Each frequency band is independently modulated at a unique rate, allowing the auditory system to be tested across multiple bands concurrently while maintaining distinguishable responses for each band
Solution Approach 2:
The patent adds the temporal modulation dimension to differentiate frequency bands. Instead of relying solely on frequency separation, each frequency band is assigned a unique modulation rate, creating a two-dimensional stimulus structure (frequency × modulation rate) that enables simultaneous multi-band testing while maintaining response detectability through frequency domain analysis
3Measurement precision
If sinusoidally amplitude modulated pure tones are used to evoke ASSR, then the stimulus is simple and frequency-specific, but only a small number of auditory nerve fibers are stimulated resulting in small response amplitude
Solution Approach 1:
The patent combines multiple frequency-specific amplitude-modulated tones into a composite stimulus that covers a broader frequency range. By merging several pure tones at different frequencies, each modulated at appropriate rates, the stimulus activates a larger population of auditory nerve fibers across multiple frequency regions, thereby increasing the overall response amplitude while maintaining the simplicity of the modulation approach
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables a clinical assessment of hearing aid performance in processing speech, providing objective and reliable verification of hearing aid fitting by mimicking real speech processing, thus improving the accuracy and reliability of hearing aid adjustments.
Implementation Method 1
When transient sounds are presented to human subjects, the summed response from many remotely located neurons in the brain can be recorded via non-invasive electrodes
Data Source
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AI summary
The application relates to a method and system for recording auditory steady-state responses of a person, the method comprising a) providing an acoustic stimulus signal to an ear of the person, b) recording the auditory steady-state responses of the person originating from said acoustic stimulus signal. The object of the present application is to excite the auditory system with a signal capable of assessing the auditory systems ability to process speech. The problem is solved in that the acoustic stimulus signal comprises a speech-like stimulus provided as a combination of a series of frequency-specific stimuli, each having a specified (e.g. predetermined) frequency bandwidth, repetition rate, amplitude and amplitude modulation. In an embodiment, the method and system comprises quantizing the amplitude modulations in time and/or level. An advantage of the disclosure is that it allows a clinical assessment of the effect of a hearing device in a normal mode of operation, i.e. when processing speech stimuli. The invention may e.g. be used for diagnostic instruments for verifying the fitting of a hearing aid.