As far as I can tell from research done for a project, interphrase has to do with the slight pause between air going in and sound coming out. Also check interphase, intraphase, and interphase if this does not coincide with the word you are seeking.
Here is a link to an article on the neuromuscular control systems in singing by the Acoustical Society of America Digital Library.
http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JASMAN0000580000S1000S94000001&idtype=cvips&gifs=yes
They double in size
Interphase
The control methods of the cell cycle include interphrase, cytokinesis, and mitosis
this is because during the interphase, the cell is at a point where it has either completed its division or is about to start its division. here the chromosomes have not separated yet in preparation for the divisin and they so look alike that one cant differentiate a chromosome.