voiced ejectives

<<<
>  FWIW, England, in her _A Grammar of Mam, a Mayan Language_
>  writes (p. 26):
>
>  "The glottalized occlusives are unit phonemes which contrast with
>  plain occlusives plus glottal stop.  Phonetically, /tz' ch' tx' ky'
>  k'/ are ejectives, with glottal closure occuring simultaneously or
>  preceding the onset of oral closure.  /b' q'/ are implosives.
>  /t'/ varies between ejective and implosive, depending on the
speaker.
>  ejective and implosive, depending on the speaker.  The imploded
>  bilabial /b'/ is always voiced in initial or medial position, but
>  is devoiced finally; /t'/ is voiced initially and medially, and
>  devoiced finally; /q'/ is partially voiced initially and medially,
>  and also devoiced finally."
Either this refers to the creaky voiced stop that replaces ejectives,
or to an implosive.
>>>
The /b/ in Yucatec Maya is said to be voiced ejective too.
Some say it is implosive and other maintain that it is pre-ejective or
pre-glottalized : [?b].
In the Lacandón dialect this /b/ wordfinal is pronounced [?].

Rob