A short summary of the filled-pause saga so far: If we call nasal-final filled pauses UM and non-nasal varieties UH, younger people use UM more than older people, and women use UM more than men. We've found this to be true in several varieties of English (sampled all over the U.S., sampled all over the U.K., from Philadelphia, from Glasgow) and in several other Germanic languages (Dutch and German). In addition, in the Philadelphia Neighborhood Corpus, where we have interviews gathered over four decades of real time as well as interviews with speakers of different ages, it appears that there is a historical trend as well as a life-cycle phenomenon. Contributions to this work-in-progress have come from Mark Liberman (University of Pennsylvania), Martijn Wieling (University of Groningen), Josef Fruehwald (University of Edinburgh), and John Coleman (University of Oxford), among others.
For more detail, here's a chronological list of past posts: "Young men talk like old women", 11/6/2005; "Fillers: Autism, gender, age", 7/30/2014; "More on UM and UH", 8/3/2014; "UM UH 3", 8/4/2014; "Male and female word usage", 8/7/2014; "UM / UH geography", 8/13/2014; "Educational UM / UH", 8/13/2014; "UM / UH: Lifecycle effects vs. language change", 8/15/2014; "Filled pauses in Glasgow", 8/17/2014; "ER and ERM in the spoken BNC", 8/18/2014; "Um and uh in Dutch", 9/16/2014; "UM / UH in German", 9/28/2014; "Um, there's timing information in Switchboard?", 10/5/2014; "Trending in the Media: Um, not exactly…", 10/7/2014.)
Below is a guest post by Martijn Wieling, adding one more Germanic language to the list.