Coding for noisy channels with input-dependent insertions

Tree encoding and sequential decoding are considered for noisy channels that respond a random number of times to each input. Such channels appear in mathematical models of certain speech recognition systems. The decoding error probability and the channel capacity are bounded by extension of the methods of Jelinek and Zigangirov to noisy multilevel channels with input-dependent insertions. Certain analytical difficulties peculiar to the channels in question are indicated.