Talk off in a meetme conferene

I have a problem with some voices occasionally being interpreted as a DTMF digit during a meet-me conference. I can see the duration of the digit is less than the minimum allowed duration set in channel.c, but it always uses emulation and accepts the digit. I can not figure out how to get the channel.c to stick with the minimum duration that is set. It is on asterisk-

Any help will be appreciated!