"a" - in all four tones (Mandarin Chinese)

My first three Mandarin Chinese private tutor sessions have been about the basics: tone and pronunciation. During the time when I was just teaching myself, I was aware of the tones, but didn't have anyone to give me feedback regularly, so it was tougher to improve because I couldn't correct my own errors. So I'm slowing everything down, and focusing on mastering the tones.

Here is a basic vowel sound in Chinese, in all four tones, repeated at varying speeds.

First tone: ā (high level)
Second tone: á (rising)
Third tone: ǎ (falling, rising)
Fourth tone: à (falling)