female vocalization info needed for Spea spp.

[paris]

I am currently doing fieldwork with Spea bombifrons and multiplicata (formally Scaphiopus). Until the other day I was using the ability to produce an audible release call as a way to sex them. I found a gravid female that had skin clear enough to see the eggs in her abdomen, but she shocked my world by also chirping very loudly repeatedly when held between finger and thumb. I have known a female Megophrys nasuta to produce a release call when pressed for it. Does anyone know of a literature review, book references, or any articles about female vocalization in North American Pelobates? (p.s. i already have "Mating Vocalizations of Female Frogs:
Control and Evolutionary Mechanisms")