I have some concern with comments involving "sudden" changes.
One must recall that the ASI is a differential pressure gauge - no more - no less, and subject to a host of pneumatic and airflow "errors". In general, in rapidly varying conditions, the instrument tells a great many fibs in respect of airspeed as calibrated.
One should only draw conclusions based on mean changes over a (short, but reasonable) period of time. Thus, when the instrument is fluctuating wildly, the "real" airspeed value is not - the instrument's gyrations reflect instrument and system problems, not the actual airspeed.