Inconsistant Tsunami Whistle Volume Levels

[Fergmiester]

I've been installing both Tsunami Medium and Heavy Steam Engine Sound decoders and am wondering if I'm missing something. Some of the Whistles are deafening while others are very faint. I've checked CV 128 and it is set at 229.
Is this volume inconsistancy typical or am I messing up the programming? Every other sound is loud and clear.

Fergie