Spikes are used in many speaker installations. They are used to decouple the speakers from the floor. Our friend Sir Isaac Newton is alive and well in many areas of audio, including the speaker arena!
Remember that a speaker is simply an electric motor. The motor movement is in and out, based on electricity applied. The outward movement produces a sound wave that radiates into the environment - your room. The backward movement also produces a sound wave that is partically trapped inside the speaker cabinet. Designers have several methods of dealing with this trapped energy, such as ports. This redirects the energy out into the room, and if designed correctly, enhances the sound. If done incorrectly, it can detract from the sound. Anyway, the energy is contained,will escape one way or another, and can cause resonances within the cabinet and environment. This is really wasted amplifier power and speaker movement if it can not be utilized.
All materials resonate (vibrate), and spikes isolate the sound energy from moving from the speaker to the floor. The contact point is very small, and most resonant frequencies can not navigate through that contact point. If allowed to travel to the surroundings via vibrations, the surrounding materials can also vibrate. This domino effect can cause similar enhancements and detractions to the sound as our example of the speaker cabinet.
Similar concepts are in place when using spikes or isolation methods under turntables and other equipment.
Regards,
BBIBH
