INDEX 



341 



Microphone, pressure, 172 



carbon, double button, 175 



single button, 172 

 condenser, 177 

 crystal, (see piezoelectric) 

 inductor, 185 

 moving, coil, 185 

 conductor, 183 

 piezoelectric, 180 



diaphragm actuated, 1 82 

 direct actuated, 182 

 ribbon, 186 

 sound power, 213 

 thermal noise, 225 

 throat, 212 



transient response, 224 

 unidirectional, 203 



combination pressure and velocity, 

 204 

 directional pattern, 210 

 phase, effect of, 207 

 sensitivity, effect of, 206 

 phase shifting, 210 

 velocity, 189 



pressure gradient, 189 

 velocity, 194 

 wind screening, 222 

 Minimum perceptible differences, 331 

 Modes of vibration of, 

 bars, longitudinal, 44 

 torsional, 46 

 transverse, 38 

 membrane, circular, 40 

 pipes, 47 



plate, circular, 42 

 strings, 36 

 Modulation, 324 

 Motion picture, screens, 285 



sound system, 282, 312 

 Musical, instruments, (electrical) 

 carillon, 240 

 organ, 240 

 piano, 240 

 voder, 240 

 scales, 334 



equally tempered, 335 

 natural, 335 

 terms, 334 



Networks, corrective, 62 



mechanical, (see loud speaker) 



resistance, 67 

 Nodal lines, membranes, 40 



plates, 42 

 Nodes, 37 

 Noise, 273 



in reproducing systems, 333 



surface, 333 



thermal, 333 

 Nondirectional microphones, 172, 305 

 Nonlinear distortion, effect upon quality, 

 328 



loud speakers, 136, 156 



microphones, 223 



plane waves, 302 



ear, 323 



Octave, 4 



Ohm, acoustical, 59 



electrical, 58 



mechanical, 59 

 One degree of freedom, acoustical, 54 



electrical, 54 



mechanical, 54 

 Orifice, circular, impedance, 84 

 Oscillating sphere, impedance, 83 



Paging systems, 296 

 Parabolic reflector, 213 

 Particle velocity, plane wave, 9 

 spherical wave, 12 

 stationary wave, 13 

 Period, 3 



Periodic quantity, 3 

 Phase, effect of, 324 



in, loud speakers, 167, 267 

 microphones, 195, 207, 252 

 inverter loud speaker, 131 

 measurement, 252, 267 

 shifting microphones, 210 

 spherical wave, 10 

 Phonograph, distortion, 238 

 mechanical, 233 

 pickup, 239 

 crystal, 235 

 dynamic, 238 

 magnetic, 236 



