Trên cơ sở của chuỗi từ sản xuất bởi người nhận bài phát biểu, một mô-đun sự hiểu biết ngôn ngữ cố gắng để trích xuất các thông tin ngữ nghĩa và để sản xuất một đại diện về ý nghĩa có thể được sử dụng bởi các mô-đun quản lý đối thoại. | Quality of Human-Machine Interaction over the Phone 75 has later been modified to better predict the effects of ambient noise quantizing distortion and time-variant impairments like lost frames or packets. The current model version is described in detail in ITU-T Rec. 2003 . The idea underlying the E-model is to transform the effects of individual impairments . those caused by noise echo delay etc. first to an intermediate transmission rating scale . During this transformation instrumentally measurable parameters of the transmission path are transformed into the respective amount of degradation they provoke called impairment factors . Three types of impairment factors reflecting three types of degradations are calculated All types of degradations which occur simultaneously to the speech signal . a too loud connection quantizing noise or a non-optimum sidetone are expressed by the simultaneous impairment factor Is. All degradations occurring delayed to the speech signals . the effects of pure delay in a conversation or of listener and talker echo are expressed by the delayed impairment factor Id. All degradations resulting from low bit-rate codecs partly also under transmission error conditions are expressed by the effective equipment impairment factor Ie eff. Ie eff takes the equipment impairment factors for the error-free case Ie into account. These types of degradations do not necessarily reflect the quality dimensions which can be obtained in a multidimensional auditory scaling experiment. In fact such dimensions have been identified as intelligibility or overall clarity naturalness or fidelity loudness color of sound or the distinction between background and signal distortions McGee 1964 McDermott 1969 Bappert and Blauert 1994 . Instead the impairment factors of the E-model have been chosen for practical reasons to distinguish between parameters which can easily be measured and handled in the network planning process. The different impairment .
