Could you please explain the difference between flat and neutral tones and, if possible, provide or direct me to an audio example. Thank you.

Flat tone is always flat. Neutral tone changes based on what tones surround it. I am getting ready to run out right now so I will find a good link for you later.

Better late then never on really replying to you, apologies! In your text books you may have seen tones introduced with numbers 1-5 something like this first chart in my link: http://www.sinosplice.com/life/archives/2008/01/21/seeing-the-tones-of-mandarin-chinese-with-praat So the tones normal pronunciation is as follows: 1st: 5-5 2nd: 3-5 3rd: 2-1-3 4th: 5-1 Thus in the above drawing it goes from point 5 to point 1 for a 4th tone character. Now, if we added in neutral tones they follow these rules: Follows 1st tone: pronounce neutral as 2 or 3 *mid* after 1st tone Follows 2nd tone: 3 *mid* after 2nd tone Follows 3nd tone: 4 *high* after 3rd tone Follows 4nd tone: 1 *low* after 4th tone Here is a similar article from anther study Chinese website http://www.chinese-forums.com/index.php?/topic/1297-is-the-neutral-tone-official/ If you ask questions about Rocket Chinese they will just redirect you here but I find Chinese Forums to be an excellent study supplement with Rocket Chinese for other general questions. This all being said, neutral tone and first tone CAN and often DO sound the same, but that neutral tone is supposed to be pronounced softer and not "sung" like a first tone. 加油!

ni hao