Can the duration of the whistle determine if food inside a pressure cooker is cooked

Building upon this question, I was wondering if the duration of the whistle can be used to determine if the food inside a pressure cooker is cooked.

As suggested by a couple of answers in the question referenced above, certain things do not work:

• The manufacture recommended two whistles in India, but in Germany it takes 6-7.


• The aroma can not always help, for example in case of making plain rice.

I have been trying to observe this event for the past few days. As the time increases, the duration of the whistle decreases (I have not measured it per se...just an observation). Has anyone else observed this. If this observation is actually correct , can this be scientifically explained?