Abstract: Using a testing sentence （Tā qù Wúxīshi, wǒ dào Hēilóngjiāng.） well designed for measurements of telephone transmission quality, we studied some dynamic characteristics of speech. 12 talkers uttered the testing sentence in an anechoic chamber individually. Testing conditions include: 1. different talker's efforts （SPL of speech at 1m from talker's lips at 56, 60, 65, 70, and 75 dB）, 2 different utterence rates （normal and speed up）. It is shown that（1）The long-term average spectrum of speech is varied with talker's effort and it is especially appeared in low and mid band of speech.（2）The fundamental frequency F₀ and formant frequencies F₁,F₂,F₃ are increased as increasing of the SPL of speech.（3）If utterance picks up speed, the vowel triangle tends to be smaller than normal i.e. the vowels tend to be centralized.（4）As a consequence of increasing SPL of speech vowel-to-consonant ratio is increased, but it depends on the manner of articulation of consonants.