A useful and practical method for fostering both peace and clarity from Ajahn Amaro.
“Nada is the Sanskrit word for “sound,” and nada yoga means meditating on the inner sound, also referred to as the sound of silence. (Interestingly, nada is the Spanish word for “nothing.”)
To detect the nada sound, turn your attention to your hearing. If you listen carefully to the sounds around you, you’re likely to hear a continuous, high-pitched inner sound like white noise in the background. It is a sound that is beginngless and endless.
There’s no need to theorize about this inner vibration in an effort to figure out exactly what it might be. Just turn your attention to it. If you are able to hear this inner sound, you can use the simple act of listening to it as another form of meditation practice, in the same way one uses the breath as an object of awareness. Just bring your attention to the inner sound and allow it to fill the whole sphere of your awareness.”
You will find that, like the breath, the sound of silence is a meditation practice you can use anytime, in any circumstance. In private moments or in public. It can be a means to “fill up” your senses when you need silence or stillness or you can hear it as a steady supportive background in challenging circumstances.
Amaro adds one important caveat for those who have a certain negative experience of sound:
“In a small number of people,the inner sound is oppressively loud, usually for an organic reason. In these cases inner listening is unlikely to be helpful as a meditation practice, since the subjective intensity of the sound makes it less useful as an object to encourage peace and clarity.”
These quotations are from “The Sound of Silence” in Buddhadarma (winter 2012, pp.26-31)