I have seen different people with different ways of choosing durian. Some of them hold the durian with both hands and shake violently to hear if there is any "knocking" sound. This is a good way to determine whether the during is ripe or not.
Then there are others who scratch (or stroke with nails) the durian skin and try to hear the sound "reflected". Again, this would require a person with good hearing.
My method was taught by my late mother who was an expert in choosing durian because behind the house was a small durian farm.
1. Look at the durian. Is the colour good, ie, fresh or not
2. Is there any obvious "holes" "drilled" by worms or not
3. Pick up the durian and check whether it is heavy or not. The lighter the better. Here, you need a little skill after a few errors. Lighter durian means thinner skin and smaller seed, thus more flesh.
4. Hold the durian with both hands and smell the bottom part. Make sure that it is clean. If you can smell a sweet aroma, the durian is guaranteed to be rich in flesh and taste good. This will also ensure that the durian is ripe.
I believe that the durian must smell "good" if you really want a good durian. However, if you want to forego the "smell" test, you can just "shake" to ensure that it is at least ripe.
A note of warning: Using my method, you won't be able to select many durians from a heap!