Footnotes for Chapter 2
1. A general discussion of the principles involved in the schematic representation of electromechano-acoustical dynamic systems can be found in BERANEK, Chapter 3 (BERANEK, 1954). Where practical, the symbolism found in BERANEK’s text was used in this work. The analog representations to be used are the ‘impedance’ analogs in BERANEK’S terminology.
2. The units of cm H2O and liter/second are fairly common in speech research and will be used even though the mks (meter-kilogram-second) or cgs (centimeter-gram-second) units are most often used in more general works in acoustics. It might be noted, however, that the units of impedance used are numerically similar to those of the cgs system. For example, the ‘Ohm’ used in this work (the cm H2O/liter/sec) is equal to approximately 0.98 times the cgs acoustic ohm (the dyne-sec/cm5).
3. The various views presented in the literature concerning the functions of individual respiratory muscles are to some extent contradictory. However, it is beyond the scope of this work to attempt to evaluate or reconcile conflicting views. Any statement in this work concerning the function of individual respiratory muscles should be considered inconclusive.
4. The elastance of a volume of air, in liters/cm H2O, is given by the volume in liters, divided by the absolute pressure in cm H2O (which is about 103 cm H2O at room temperature and pressure), assuming isothermal compression or expansion. For variations of pressure fast enough so that there is no heat transfer to the walls of the container, one must use the adiabatic compressibility, which is 1/1.40 times the isothermal compressibility. Since in this work we are interested in the slow, or average, variations of pressure, we will normally compute the isothermal compressibility. Thus values of volume-related capacitance computed in this work might be up to about 30% too high when considering the faster variations of pressure.