:0 identical loudspeakers are driven in phase by a common oscillator at 840 Hz and face each other at a distance of 1.26 . Locate the points along the line joining the two speakers where relative minima of sound pressure amplitude would be :pected. (Take the speed of sound in air to be 343 mls. Choose one speaker as the origin and give your answers in order increasing distance from this speaker. Enter 'none' in all unused answer boxes.)