Voice samples are always a thorny problem for narrators in Japan.
The primary issue is that the people who do the choosing for a TV commercial or PR video or web video are Japanese – usually mid level managers at companies. They hear with Japanese ears, thinking of an audience just like themselves – other Japanese salary men. So, they may choose a female voice when a male voice would be more effective. Or, they may go for British English when they should choose American. They tend to dislike “natural “intonation -- preferring the kind of diction they get with English language practice materials. “Deep” female voices are “out”. And the rougher, more raspy male voices so beloved of American and British audiences somehow bother them.
Listen to any TV commercial in Japan, done in English, and you will almost always hear a voice that is mid range, “pure”, “neutral” and rather low impact.
There are exceptions of course. The old “It’s a Sony” is one. And the “Honda Prelude” is another. But these are rare cases.
Obviously, mid-level managers are going to go for “safe” choices”.
So, what to do when making a voice sample?
In the US, voice samples, are often 10 second clips stitched together to show a variety of styles and characters. This is great for TV commercial stuff. But here in Japan most of the work is going to be corporate communications vehicles such as PR videos. Such longer examples of narration that mimics standard PR video scripts is better. Focus on clear diction and enunciation.
English practice materials redux.
Your audience are the kind of guys you teach at the school you teach at to make up for times when there just isn’t narration. These are often the only people who are really going to listen to your work anyway.
Yes, there are exceptions.
But most PR videos end up in showrooms, rarely played. Or played to foreign guests as a kind of ordeal they must endure before dinner and drinks.