In model Mandarin Chinese usually has four pitched tones and a “toneless” tone.
|2nd||bá||Starts medium in tone, then rises to the top|
|3rd||bǎ||Starts low, dips to the bottom, then rises toward the top|
|4th||bà||Starts at the top, then falls sharp and strong to the bottom|
|toneless||ba||Flat, with no emphasis|
The tone can be change, a fouth tone can change first tone.but the meaning not change.
爸爸 bà bà = bāba it means father,dad
妈妈 mā ma = ma it means mother,mom