The antipodean curse

Many people, particularly when speaking in front of a group, have a tendency to allow their voice to go up at the end of sentences.
This has been called the 'antipodean curse' because it is sometimes said to be a particular characteristic of many New Zealanders!
(Although to be fair - many other nationals are equally prone.)
From a purely musical point of view this means the audience lacks a sense of cadence.
A voice going up at the end of a statement tends to sound unsure of itself.
Try saying:
'And your name is John.' - with a questioning intonation (ie going up at the end)
It now sounds like you are actually asking for confirmation of the person's name.
Equally, try:
'Do we all agree.' - with the voice going down at the end and it will probably sound more like a challenge than a question.

The reason this is so relevant to a speaker is because often under pressure, there is a tendency for our voices to go up.  It is almost as if, under pressure, we are asking ourselves: 'Do I know what comes next?'
Add to that a little bit of shallow breathing that often comes with nerves and the voice will tend to become thinner and higher anyway.

Speakers and Trainers need to command a level competence in front of their audience or students
and a lot of the confidence that we inspire in others comes from how we use our voice.
Also bear in mind, usually, when we think of training, we think of 'gathering the facts', learning 'how to', or receiving clear instructions on what to do next.

However if you consider some of our every day phrases and metaphors you begin to realise that on a scale of up and down, we usually associate clarity and hard facts with down and vagueness and lack of substance with up:
ie, the 'known' is down and the 'unknown' tends to be up.
Hence we talk about situations being 'up in the air' and individuals 'floating with their head in the clouds';
whereas we get 'down' to business, 'settle' a question, establish the 'basis' of an argument, and describe a sensible person as being  'well-grounded' or 'down-to-earth'.

In the same way as the speaker standing solidly on the ground sends the audience the metaphorical message - 'I know where I stand',
a voice that leads to a clear cadence suggests standing on firm ground rather than floating in the clouds.
So, if there is a tendency for your  voice continually to go up at the end of sentences, it helps to consciously make sure the voice occasionally comes down as well.
This will make the speaker's argument sound more 'grounded' as well as focusing and encouraging the speaker to use the whole range of their voice.
That way you are more likely to sound like you are 'getting down to business', rather than 'floating vaguely in the air'!