What is silence?
Silence is a lack of music - i.e. "no music". We actually need to add (i.e. to perform a work to add) the word "no" in order to perform a subtraction of waves and reach a condition of silence. Actually, we imagine a universe that is always filled with something, from sounds to cosmic rays. In order to obtain a silent spot, we need to shield it from any influence.
A performer is used to think in opposite terms. He must produce the sound that will fill the hall, starting from a silence condition. In the true, he is bringing in the hall nothing that is not there already. He only introduces the energy - and then directs it - that allows sounds to manifest.
The istrument in on the stage. It contains all the needed frequencies. When a chord is plucked, it generates a frequency with all its harmonics. The hall responds by resonance to frequencies and harmonics, creating the so called "later reflections". The entire environment becomes alive and participates in the concert.
Every object in the hall and parts of it contribute with their specific resonances and reflections. They are as additional instruments, which starts playing when they are activated by the correct frequencies produced by the instruments on the stage. Our entire environment is filled with potential sources or reflectors of sound. When a performer plays his instrument, he is not only doing that, but he is setting the entire environment in motion.
Acoustics is somewhat a taboo topic among musicians. However, much of the success of the concert depends on the architecture of the place. A proper awareness of this issue is a first step in eliminating those variables that so often cause substandard performances. Many players attribute to luck the choice of the hall. Indeed, just a few people less or more in the room will cause different acoustic reflections (more people act as a shield, less people increase reflections), thus affecting overall performance. A sound can easily turn from clear, defined, and brilliant to opaque and muddy.
Silence is the art of helping sounds stand out, minimizing reverberation. The tempo of the concert needs to be chosen not only as it was indicated by the composer, but also by the reverberation time of the hall. If reflections come slow, such as it usually happens in a church, they will corrupt every next sound, if it is not well spatiated and sculpted with pauses. This also impacts the way of playing the instrument. In an echoing hall, it might be better to play all in a staccato way, rather than legato.
When writing music, we should refrain from exaggerate harmonical constructs or extra long sustained sounds, because we need to create contrast. This can be achieved only by a wise use of pauses, whether in a melodical line of a single instrument or a general pause. Silence adds breath and life to music. As a similitude, we cannot talk while we inhale air. We can modulate air with our voice only when we exhale it. Music should be the same and reproduce the natural flow of things. A charge needs a discharge time.
A pause can be a short instant needed to take breath (singers, woods, brass) or an extended period of time - implicit vs explicit. Synthetized electronic music is usually unable to reproduce these dynamics, which are typical of a live orchestral performance. Therefore, it will always sound unnatural to a certain extent.