Intelligible Crosstalk Performance of Voice-Frequency Customer Loops

A telephone user occasionally receives an extraneous speech signal as a result of interference between communications circuits, which is referred to as crosstalk. Crosstalk not only produces annoyance to the affected customer but also constitutes loss of another customer's privacy when it is intelligible, and is an important concern in transmission systems design and planning. For example, if, with the advancement of loop electronics, gain devices are applied on loops to enhance the speech signal level, the maximum allowable amount of gain and the location of its application may be restricted by the resulting crosstalk performance degradation. In this paper, a methodology is developed for evaluating 3001 the intelligible crosstalk performance of voice-frequency customer loops that can be used in loop transmission systems design and planning. In particular, the methodology can be used in (i) establishing loop crosstalk performance objectives, (ii) allocating the objectives to components of the loop plant, such as cable facilities, central office switches, and customer-premises wiring, and (iii) evaluating effects of new technology and new loop design rules on crosstalk performance. Intelligible crosstalk performance is measured by the crosstalk probability, which is defined as the probability that a customer will hear one or more intelligible crosstalk words during a call. The crosstalk probability on customer loops depends on the probability distributions of such random variables as call holding time, quiet interval between calls, disturbing talker volume, crosstalk path loss, circuit noise, and disturbed-listener hearing acuity.