Tones

Chinese is a tonal language, i.e. a sound pronounced in different tones is understood as different words. So the tone is an indispensable component of the pronunciation of a word.

Basic Tones
There are four basic tones. The following five-level pitch graph shows the value of the four tones:
Pitch Levels
 

The First Tone is a high, level tone and is represented as ¯, e.g. 妈 (meaning mother, mom).
The Second Tone is a high, rising tone and is represented by the tone markˊ,
e.g. 麻 (hemp or sesame).

The Third Tone is a falling and rising tone. As you can see from the pitch graph it falls from below the middle of the voice range to nearly the bottom and then rises to a point near the top. It is represented by the tone mark ˇ, e.g. 马 (horse).

The Forth Tone is a falling tone. It falls from high to low and is represented by the tone mark ˋ, e.g. 骂 (curse).

In Chinese speech, as in English speech, some sounds are unstressed, i.e. pronounced short and soft. They do not have any of the four tones. Such sounds are said to have Neutral Tone. Sounds with neutral tone are not marked. For example in 爸爸 bàba (daddy) the first syllable is pronounced in the fourth tone and the second syllable in the neutral tone, i.e. unstressed.

Tone Changes

Tones may undergo changes in actual speech (“tone sandhi”). The third tone, when followed by a first, second, fourth or neutral tone sound, loses its final rise and stops at the low pitch. Followed by another third tone sound, it becomes the second tone. This is a general rule and the notation of third tone sounds remains unchanged.

For example, in 所以 suǒyǐ (therefore, so), notation remains the third tone for both syllables, but the word is actually pronounced like suóyǐ.

Two important words 不 (no) and 一 (one) also undergo tone changes. You will find the details of their tone changes under those entries.

Syllables

Chinese Syllables: Distinct Units
Normally a consonant and a vowel merge to form a syllable in Chinese. Every syllable is a distinct unit in speech. Learners should say each syllable clearly and give full value to most syllables in speech. The general impression of Chinese speech, described in musical terms, is staccato rather than legato (which could be used to describe English).

Syllable Division Mark
As Chinese syllables are distinct units and should not be liaised with preceding
or following syllables, a syllable division mark (’) is sometimes used to avoid
confusion, e.g. shí’ èr, píng’ ān, tiān’ é.