SPEECH POWER AND ENERGY 641 



is large romnarccl with — -, this chaiiKc in shape becomes negligible. 



In the case of sjieech, since the source is of linile size the effective 

 radius is somewhat greater that that measured from the speaker's 

 lips, and the wave front is not exactly hemispherical, so the com- 

 parison is onl\- qualitative. Nevertheless, a difference in quality 

 of transmitted speech can be detected when the speaker's lips arc 

 within 2 cm. of the transmitter (iia[ihragm. 



