Increasing aspiration of Swiss German plosives: A Sound change in progress?

In Alemannic dialects of German-speaking Switzerland, the primary cue between lenis and fortis plosives is closure duration, with lenis plosives having a shorter closure than fortis plosives, while both are phonetically voiceless. Recently, it has been called into question whether there is an increasing tendency for speakers to additionally produce aspirated fortis plosives, possibly due to the contact to German Standard German. To investigate this, we recorded word-initial and word-medial fortis plosives produced by 24 older and 24 younger speakers of Zurich German and analysed their normalized VOT values. Results show that, although the word-medial plosives can probably all be considered unaspirated, younger speakers overall produced significantly longer VOT values compared to older speakers. Word-initial plosives differed much more between age groups and also resulted in considerable variability for certain words. These new results hint at a possible sound change in progress