Face Mask Speech Distortion Measurement System
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Solution Overview
Problem
Face masks distort and muffle speech, reducing communication effectiveness, particularly for healthcare workers and others required to wear them, and there is a need for a quantitative method to measure this distortion.
Innovation Solution
A system comprising a simulated voice source, vocal tract, face mask, microphone, and analyzer to objectively assess speech distortion and muffling by comparing sound spectra with and without the mask, using a manikin head to simulate mask fitting and measuring frequency, amplitude, and bandwidth changes of formants.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If face masks are worn to protect against airborne pathogens and particles, then protection against inhalation of infectious particles is improved, but speech intelligibility deteriorates due to distortion and muffling
Solution Approach 1:
The patent replaces the subjective human ear and brain processing of speech with an objective electronic measurement system. A microphone captures speech signals, an analyzer processes the spectral content, and a quantitative distortion metric is calculated. This mechanical/electronic substitution eliminates the variability of human perception and provides objective, repeatable measurements of mask-induced speech distortion, enabling scientific evaluation and comparison of different mask designs to minimize communication impairment while maintaining protective function
Solution Approach 2:
The patent changes the measurement parameters from subjective speech intelligibility ratings to objective acoustic spectral parameters. By analyzing formant frequencies, spectral envelope, and power spectrum density, the system quantifies distortion in terms of specific acoustic parameter deviations. This parameter transformation enables precise measurement of how masks alter speech characteristics and facilitates optimization of mask design to preserve speech parameters while maintaining filtration effectiveness
2Measurement precision
If quantitative measurement methods are developed to assess speech distortion, then measurement precision is improved, but device complexity increases due to the need for specialized equipment
Solution Approach 1:
The patent uses a simulated vocal tract model that replicates the acoustic properties of the human vocal system. This physical copy allows measurement of mask effects on speech parameters without requiring actual human subjects, enabling controlled, repeatable experiments. The simulated tract can be acoustically characterized and used to establish baseline speech parameters for comparison with masked speech, providing a standardized reference that simplifies the measurement process while maintaining scientific validity
Solution Approach 2:
The patent introduces an acoustic coupler or simulated vocal tract as an intermediary between the voice source and the face mask. This intermediary component standardizes the speech signal input, ensuring consistent acoustic conditions for measurement. It acts as a mediator that translates electrical or mechanical voice source output into acoustically realistic speech signals that interact with the mask in a controlled manner, facilitating precise measurement of mask-induced distortion without the variability of human speech production
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
Provides a quantitative assessment of speech distortion and muffling, enabling objective and repeatable measurements of the acoustical effects of face masks on speech intelligibility, allowing for improved communication in masked environments.
Implementation Method 1
a simulated voice source, configured to produce a sound
Implementation Method 2
a microphone, configured to produce a signal
Implementation Method 3
analyzer, configured to receive the signal from the microphone... the analyzer may further produce a quantitative assessment of the distortion and muffling of the face mask
Data Source
AI summary
Systems and methods are provided for measuring the distortion and muffling caused by a face mask. For example, in one embodiment a simulated voice source produces a sound. The sound is then acoustically coupled to a simulated vocal tract and a face mask. A microphone receives sound and produces a signal and an analyzer receives the signal from the microphone. A manikin head or other facial structure may also simulate fitting of the face mask onto a face. The analyzer may further produce a quantitative assessment of the distortion and muffling of the face mask, for example, by comparing at least one spectrum obtained with the face mask and at least one spectrum obtained without the face mask.