Speed and RPM controlled changes of speech intelligibility: a new computerized method for measuring the communicative quality of car interior sound

摘要

Speech intelligibility more and more turns out to be one of the most important features of car sound quality as there is an increasing demand of the market to improve the verbal communication within the car. Classical methods for the assessment of speech intelligibility, e.g. based on the complex modulation transfer function, have the disadvantage of being not very well suited for tracking highly dynamical changes within the acoustical environment of a driving car. To measure reliably speech intelligibility during varying conditions due to speed and RPM a new method (SVI) was developed being based on human speech production. The validity of the method could be demonstrated in a series of psychometric experiments in the laboratory and on the road. When applying the method to practical problems it was found that an excellent differentiation relative to sound quality between various driving and car conditions could be achieved.