JAZZ REVIEW : * RICKIE LEE JONES “Pop Pop” <i> Geffen</i>

This brave but misbegotten effort (due to be released Sept. 24) is the latest and lowest in the series of pop-to-quasi-jazz crossovers.

Rickie Lee Jones’ timbre has all the maturity of a 12-year-old trying to sound grown up; in fact, she is well suited to “Dat Dere,” the lyrics of which are in baby talk, and the aptly titled “I Won’t Grow Up.”

When she tries to sing adult songs, all her problems stand out like sore throats: the marble-mouthed diction with the Barbara Walters lisp, the awkward phrasing, the intonation lapses (listen to the line “My condition must be chronic” during “Spring Can Really Hang You Up the Most”).

Does she have a bad cold or was that just a sinus condition, or is this her idea of sounding soulful? And why would she attempt harmonically rich songs such as “My One and Only Love” but surround herself with a thin, empty backing?

Robben Ford tries hard to hold things together with his acoustic, nylon-string guitar, and Charlie Haden’s bass helps here and there, but the odd instrumentation--there is even a bandoneon on three cuts, played by Dino Saluzzi--just doesn’t work. The best tracks (or the least contrived performances) are the last two, in which she abandons all hope of joining the jazz sorority and sings tunes by producer David Was and Jefferson Airplane-era Marty Balin.

Natalie Cole, you have nothing to worry about.