[asterisk-speech-rec] SpeechBackround: accepting DTMF and speech at the same time? Why?

[Tom [toms400]]

A number of my users have phones that beep when each number is
pressed.  It appears that the SpeechBackground app is picking up this
sound, interpreting it as speech, and returning an invalid result.

Looking at the source it seems that the app looks for both DTMF and
speech in parallel?  Is this correct?  Is there a straightforward way
to to destroy the speech engine but continue to receive the DTMF input
the instant DTMF is detected?

Thanks