Primary Sounds (version 1)
In this picture you can see the Three Mother Letters of Sefer Yetzirah:
See the large Hebrew letter Aleph א?
Now look at the yellow diagonal line. It can be seen as the Hebrew letter Vav pronounced Wow. It can also be seen as the numeral One. The Wow of this Aleph balances and united the red Shin ש the blue final Mem ם.
The Three Mother Letters, Aleph, Mem and Shin are primary sounds.
Aleph is a silent letter that represents the Breath of Air that forms the sounds of all spoken letters.
Shin is a hissing sound formed with open lips and the breath coming out between the teeth.
Mem is the opposite of Shin. Mem is a humming sound formed with closed lips and the breath resonating inward.
From Sefer Yetzirah:
"Three Mothers Letters Aleph, Mem and Shin are Air, Water and Fire.
Fire is above, Water is below,
and the Breath of Air balances between them.
Mem hums, Shin hisses, and Aleph is the Breath of Air between them.
Three Mother Letters Aleph Mem Shin in Soul are
the head, the belly and the chest.
The head is created from Fire, the belly is created from Water
and in the chest is the Breath of Air that is between them."
This picture can used as a focus for meditation. Sit comfortably and become aware of your chest rising and falling with your breath. Now breathe in through your nose down into your belly with your lips closed. This is the Mem. Open your lips and breathe out through your teeth. This is the Shin. If you want to deepen this meditation, pause in the space in-between the in breath and the out breath. Be aware that your chest is full. Pause in the space in-between the out breath and the in breath. Be aware that your chest is empty.
Becoming comfortable in transitional or liminal spaces - like the space in-between the breath - allows us to have more Wow experiences and become more Spiritual. In Sefer Yetzirah the Hebrew word that is used for Breath is רוח Ruach. This word also means Spirit. It can also be read Revach רוח - space. Thus, Mem hums in the in-breath; Shin hisses in the out-breath; Aleph completes the Breath with the spiritual space in-between them.