Ditch using the question inflection. It's killing your credibility!
The question inflection is when our vocal pitch goes up at the end of our sentence, sometimes referred to as upspeak. We naturally do this when we ask a question. However, when we do it when making a statement, we turn our statement into, what sounds like, a question. It comes across like we're questioning our own words. Imagine, stating your fee, with inflection:
"... will be $500"
Try it. Try it with and without inflection.
One definitively states that your fee is $500, the other says, "My fee is questionable, negotiate with me". Can you see the significance of this, and the potential influence it may have on the way your words are perceived?
I'm not saying we shouldn't have inflection within our statements, as vocal variance is important and keeps people engaged. However, inflection at the end of a sentence should be reserved for a question, or when we don't have confidence in our words and we want to communicate that.
I've worked with people, who don't ordinarily use the inflection (unless in a asking a question), practice a presentation and suddenly use it at the end of a statement, during some parts of the presentation. This clearly signals (and they admit), that they aren't confident with their words. It's a true representation of how they are feeling, but perhaps one that they should disguise when actually presenting in public, to avoid losing credibility.
Australians use the question inflection (for statements) a lot, and I seem to remember this also became a bit of a trend in the UK, some 15-20 years ago. I'm not sure if the trend continued there or not. At the time I lived there, I thought this sudden change in the way some people talked, was a little odd, but I had no idea of its meaning, so didn't pay much attention to it. I wonder what sparked it- Neighbours and Home & Away perhaps, or possibly American Pie!
Now that I understand about nonverbal communication and the meaning and significance of the question inflection, I can't help but hear it. It's like finger nails scraping down a blackboard (not in how it sounds, but rather, in how it is perceived)! The crazy thing is, many people in Australia do it. I don't think it's simply part of the Australian accent, because not all Australians do it.
If so many people in a nation do this, does it become less significant as a negative nonverbal cue?
I don't think so. Because, nonverbal communication is picked up and processed mainly at a subconscious level. We may be so used to hearing the question inflection in Australia, that we don't consciously pay attention to it. But, I'm pretty sure our subconscious will still be picking it up, signalling an emotional response that triggers doubt. And as a multicultural nation, we're constantly communicating with people from other cultures. Cultures that perhaps reserve the inflection to questions only.
Since becoming aware of the meaning of the question inflection, I seem to have developed a heightened sensitivity to hearing, and feeling it. It sounds at odds with the words it delivers. I hear it from both men and women and across generations. At times, I've even heard my own stubborn, Northern English accent slip one in! It seems I'm not immune to it myself, but at least I'm aware of it- as you are now, too.
Let me remind you of the statement, "... will be $500", or the question, "... will be $500?"; depending on how you say it.
So, now that you're aware there could be a big issue in how your words are perceived, the next step is to listen. Listen out for the question inflection, from both yourself and others. Note when you use it, and explore by playing with its use (in a safe environment and perhaps, not when stating something important). See if you notice a difference in responses you receive from others, when you do or don't use it. Before long, every time it's used by yourself or others, you'll notice it. This has to be a good thing, because then you'll start to gain control over how you use it yourself.