Achieving silence of the mind has always been a primary goal — or perhaps rather requisite — of an appropriate and successful meditation practice.
Silence of the mind then means to come to an end of following and fueling the constant chatter of our minds — our thoughts, ideas, and concepts — being able to attain one-pointed concentration, preferably concentration on “no-thing at all.”
Moreover, reaching a state wherein one doesn’t follow the thoughts that arise in the mind also calms down the emotional load attached to and induced by those thoughts. Silence of the mind means that one becomes still and silent, being able to see what-is — becoming consciously aware — of what’s beyond the external and internal phenomena that arise in order to find Spiritual Enlightenment or Self-Realization.
An obvious external help to reach internal silence is of course to be in a tranquil environment. That may be somewhere remote in nature, or perhaps in a room that is devoid of external noises. Certainly in the beginning of one’s meditation practice it would be hard to find the concentration to reach internal stillness in an environment that is agitated, loud, and/or characterized by many changing visual and auditory impressions.
Additionally, across the millennia, a vast range of techniques have been developed to achieve a condition of internal silence. Think of Yoga Asanas, Pranayamas, Breath Awareness and Breathwork, a variety of nature and sports activities, Mindfulness practices, Abstinences and Celibacy, among many others.
These techniques all work in different ways to combat and handle “disturbing” internal and external phenomena, the latter including sounds, noise, thoughts, physical pains, emotions, detrimental desires, traumas, nervousness, anxiety, stress, restlessness, and so on.
Nevertheless, the main goal is and has always been the same — coming to calmness and equilibrium, full relaxation of body and mind, and thereby creating the optimal conditions for one’s meditation practice.