This standard provides the techniques and rationale for referencing acoustic telephony measurements to the free field. It applies to ear related measurements such as receive, sidetone and overall. A common acoustic reference point is needed for comparing electroacoustic performance of handset, headset, handsfree, and other kinds of telephone terminals. It is also needed for comparing telephone terminals with other devices such as loudspeakers, mobile communication devices, multimedia terminals, and consumer audio equipment. The free field is the appropriate reference point because the results relate closely to what is heard by the listener. Therefore, the free field is a more widely applicable reference point for telephony measurements than the traditional ERP (ear reference point). New IEEE Standard - Superseded. This standard provides the techniques and rationale for referencing acoustic telephony measurements to the free field. It applies to ear related measurements such as receive, sidetone and overall.