Vignana Bhairava Tantra - 42

Beejakshara Sounds

Pinda Mantrasya Sarvasya Sthoola Varna Kramena tu
Ardhendubindunaadantaha Shoonyoccharaad Bhaveth Shivaha

Pinda is an egg. Egg is a seed, also called Beeja. Mantra is a word, when expanded, reads as Mananath Trayate Iti Mantraha - that sound which protects and liberates the mind. This Tantra says that, when one chants all the Beeja Mantras - letters of the Sanskrit alphabet dotted with a Makara or the sound of mmm...., the mind gets attuned to the most subtle vibrations that merges into consciousness. The way to chant these Bija mantras - for instance Aum...is like this.
Take in a deep breath. Experience the awareness in the navel region. When you exhale, let the breath go out with the sound of Om. After the sound is chanted fully, be with that silence and space. That is the experience of merging with Shiva. - Swahilya Shambhavi.

Vignana Bhairava Tantra - 40

Merge with the silence before and after sound

Yasya Kasyapi Varnasya Purvantavanubhavayet

Shoonyaya Shoonyabhootosau Shoonyakarah Puman Bhaveth

Whoever meditates on the silence before the chanting of a mantra or sound and the silence at the end of the mantra - such a person who meditates on the silence, stillness and void - becomes that which he meditates upon.

Just like sound which has vibrations of a particular wavelength and frequency, silence also has the highest frequency of vibrations. when the mind focusses on something for a while, it becomes that. In this method, the mind that focusses on the silence becomes the silence itself. - Swahilya Shambhavi. (Picture taken by Bina Aditya during the Dua at the Sufi Dar in Chennai - a place where God in every form is worshipped.)