There are various reasons why listening comprehension in Chinese is difficult. In addition to those máfan tones, a homonym minefield, and countless regional accent variations, it's also important to know Chinese has reductions. Much in the same way English has words that get crunched together and some sounds fall aways (like "going to" becomes "gonna"), here are some examples of Chinese reductions that can throw your listening comprehension for a loop if you're not ready for them.The reduced sound on the other side of the "->" arrow is my own approximation of what it sounds like to me, and is not standard pinyin.

bǐjiào 比较 ->bǐyào

Here's a link to an audio file (you'll need Quick Time) and PDF transcript where this reduction happens in the first sentence. This resource, Working with Spoken Chinese, headed up by Professor Hongyin Tao at UCLA would be great if it had English translations on the transcripts. But, it doesn't.

duōshao qián 多少钱 -> duō'ao qián

I don't have any recordings to prove this (yet) but, watch for it. That "sh" just drops right away.

bù zhīdào 不知道 -> bù rīdào

The "ri" there more resembles the actual Chinese pronunciation of the "ri" combonation (like in rì 日). I'm sure it's not exactly the same, but that's kind of what it sounds like to me. Regardless or what it is, it certainly doesn't have the hard "d" sound at the beginning of the "zh" that it usually does.

bú è 不饿 -> bè

Interestingly, the "be" combination doesn't appear on the Pinyin Chart, but I've heard it clear as day when someone wants to say quickly how hungry they aren't. Other common phrases starting with "bù" 不 seem to leave out the "u" just like this (for example, "bù hǎo" 不好 sometimes sounds like "b' hǎo" to me when it's said fast).

For Listening Not Speaking

I'm not suggesting we talk like this, because there are probably various little subtleties to saying these reductions "correctly" that we don't know about. I'm still going to try to say everything as clearly as possible (although, I must confess that I do try to use the reduced forms of these from time to time, just as an academic experiment to see if I'll be understood). Identifying these is mostly to help with our listening.If anyone else has noticed these or other reductions that I haven't mentioned, please feel free to leave a comment identifying the phenomenon. Also, if anyone comes across any recordings that demonstrate these, for example at Chinesepod, please leave us the link and what time (approximately) in the file it happens at, so we can hear it for ourselves.