The technical factors to reproduce three-dimensional holographic "sound-image" and "sound-field" are studied are actually proved. It is clarified that very severe reproduction of the wave front is neccessary; woofer, suquaker,and tweeter should be set within 1mm in depth and within 5μsec in delay time. The undesired modulation of the wave from must be strictly removed. Nonmagnetized and nonvibrational components,nonvibrational coaxial cables,and rigid chassis are help to reproduce rigid wave front. The viblational modulation of chassis and speaker-box must be strictly removed. Common mode noise must be strictly removed also. Consequently very impressive holographic "sound-image" and "sound-field" are reproduced.