A siren

[kickingtone]

My siren

(it's getting to where I want it to be, but it is still work in progress)

https://soundcloud.com/kickingtone/sah004rvp

(I've deliberately allowed the harsh open tones at the high end of the scale, rather than alter the vowel.)

NB It is all my own opinion, so don't let it turn into a slanging match as it has in the past. If you disagree, why not post your own siren and explain the differences.

Objectives:

1. Throat, larynx, upper body and vocal tract should be completely relaxed and naturally posed. Nothing much going on there.

2. All effort is concentrated in the abs, trunk and diaphragm, regulating air flow and freeing the larynx. This should enable you to glide through the passaggio.

3. Maintain a single placement. Don't flip registration.

4. Keep effort uniform throughout. Any volume change (and it can be quite substantial) is caused by resonance shift only.

5. Sing on one vowel** but allow vocal tracts resonance shifting to cause its natural change in vowel.

6. Keep the siren slow. You should be able to hold abruptly at any point. 

7. Relax. No "blasting" to force ascent at any point.

8. Control. No collapse on descent.

9. Both ascent and descent are important.

10. If you are running out of breath in the 20 seconds, your breath support is probably inefficient.

** But close the vowel to protect your vocal cords from damage if you find the vowel is too open to sing safely at higher pitches. 

A characteristic heady resonance may kick in at around A4 for males. It may not sound pretty. Don't worry. The exercise is taking you through the second passaggio. Don't let it become a psychological barrier.