This paper deals with problems concerning the nature of the input to a phonetic processor. Several assumptions provide the basis for consideration of the problem. There is a phonological level of processing which reflects the sound structure of the language; the rules associated with it are not affected by variables associated either with the motor system or the environment. One level of processing can be called motor planning, another can be seen as executing the motor plan, and a level of control operates over the execution of the motor plan. The discussion that follows these assumptions concerns the phonetic processing mechanism and raises larger questions concerning the interrelation of linguistic competence and performance. A bibliography is included. (Author/VM)