FOUR REASONS WHY CHINESE LISTENING IS SO DAMN DIFFICULT
It takes listening, speaking, reading and writing to make a language complete, and listening is always the hardest part to crack. Compared with reading and writing, you have limited time to react, without any possibility to go over a certain wording for times the way you do when reading. Moreover, reading doesn't involve pronunciation and sometimes you may find that you understand what's been said once you have the script of the listening materials. What'll be said and the way it sounds, the speed it takes depend on the person leading the conversation, and the uncertainty of content, accent and pace make listening harder than spoken Chinese.
Conclusion above is based on the assumption that the degree of complexity stays the same. Characteristics of Chinese below make you need more time to figure out the content orally expressed, and further the uncertainty of Chinese listening.
1 Different characters in the same pronunciation
There are several characters sharing the same Pinyin, and you have no idea what's talked about without connecting it to the words around it or putting it in the context. You won't see the difference about 气, 器, 弃 since they sound the same. And you have no idea which of the following is mentioned here, 中指, 终止or 中止if "zhong zhi" is all you hear. Such a high frequency in application of same pronunciation makes Chinese confusing to foreign speakers. Therefore, memorizing the characters in words, and minding how the certain word match with the other (collocation) mean a lot to improvement of Chinese listening skill.
2 Standard Mandarin challenged by dialects
Not every Chinese speaks standard Mandarin like the host or hostess in broadcast. Unfortunately, people living in different areas of China have a lifelong battle against their dialect's negative impact on Mandarin pronunciation. This could be a huge influence since Chinese dialects vary a lot from each other. You know the English is speaking English even if he has accent, but you don't know the Chinese is speaking Mandarin if he sounds much too dialect influenced. However, it's not the reason that you could slack off in practicing standard Mandarin. On the contrary, you should be familiar with Mandarin pronunciation to know which pronunciation is likely to be influenced by dialect and how it is affected, so you could realize which character is about even if it is not pronounced in perfect Mandarin. Be well prepared with the Mandarin blending with several dialect, so you are not losing confidence when you doesn't sound good for the moment, and you won't be too shocked when some Chinese disappoint you with their pronunciation far from perfect.
3 Pronunciation in monosyllable with tones unfamiliar to non native speakers
Characters are pronounced in monosyllable no matter how long its Pinyin seems to be.
Each character is pronounced separatedly, like water drops falling down to hit the ground one by one, different from liaison in English, which sounds like a river flowing forward. Say each Chinese character independently without lengthening the sound or make them connect to each other. That's the way how Chinese is spoken, and familiar with such a style in pronunciation does matter to your listening. It is true that some Chinese students claim that the listening materials in English test will be easier to understand if the announcers making the audio tape speak English the way they do, pronouncing each t, d, k at the end of each vocabulary clearly, without consonant at the end of a word connecting to the vowel at the beginning of next word. Be familiar with the pronunciation rules and style of a language does smooth the process of listening comprehension. We may understand in seconds if our own pronunciation is identical with how native Chinese people speak Chinese.
4 Wording out of range
There are words you seldom come across in text book or literature reading, and you are likely to get trapped if they show up in the conversation. Make yourself exposed to 成语, 谚语, 歇后语, 网络热词, 双关语, etc, and listen to conversation or materials with topics close to daily life. I am not recommending CCTV news but you could try it if it is not boring to you. Documentary in CCTV 9 will be good choice but go get some refreshment before it makes you doze off. TV shows recording how people are asked to finish the tasks or introducing you to something worth your attention or place worth visiting (综艺节目, 游记, 美食节目) are easy for you to cling to and follow through. The more you don't understand, the more you need to practice listening. We didn't understand most of our parents' conversations when we were around two or three, but we still listened until we learned enough to comprehend what's been said. Therefore, do not say no to listening material because you understand little about it. Try and you may find even if you can't tell the meaning of a word you are still getting familiar with the way Chinese is spoken, how Chinese people describe things and what kind of wording they choose. It is a process of accumulation hidden but may see its meaning as you proceed with and finally make what you've heard part of your wordings.