Hi Andy!
What have you tried? I’ve managed to solve this issue by using these methods below, but you may have already tried them:
First, strengthen the high chest voice, before the transition:
– Call out “Hey!” “Oi!” “Yeah!” to access a clear, high chest tone which gets the reflex strong sound out
– Scales that are “ma” rather than vowel sounds as it stops too much airflow
– 5th Slides on a hum to “iron” out the breathiness and connect with the core
Then when it flips to falsetto:
– Suddenly dip the volume so they’re not pushing more air through (I find that they forget that this is a much less “forced” sound than the chest voice) it has to be just the right balance of airflow in order to create a clear, pure tone. It may only be achieved at an even higher part of their voice
– Get them to sing like they’re yawning to get the back of their throat to open
– Also think of a “choir boy” or “opera” sound to help them mimic what this might sound like!
– Get them to do the slides again in order to assess which notes can come through clearly
I hope this helps but I imagine you’ve already tried – some male voices just don’t have much of a falsetto range..!