It is forbidden to read Krias Shema opposite a tefach of a woman’s skin that is normally covered. But her face and hands are not a problem. (ShA 1 – MB 2) “Krias Shema” – not only Krias Shema, also Torah and tefilla and any topic of kedusha. This applies wherever “Krias Shema” is mentioned from Siman 74 to Siman 88. (Siman 76 MB2) “opposite” – the poskim argue if it is enough just to be careful not to look at all or do you have to turn aside. Only when there’s no other choice can you be maykil. (MB 1) “woman’s” – even your wife – even a girl from age three unless she’s your daughter, then it is an ervah from age eleven. (ShA 1 – BeH “tefach”) “normally covered” – from the knee down is an ervah only in places that the custom is to cover it. The (upper) arm and thigh is ervah even in places that they are regular to go around with them exposed. (MB 2)
Some poskim say that if she is not your wife, even less than a tefach of skin is ervah, but for this you don’t need to turn aside – just close your eyes. (Rama 1 – MB 5)
It is forbidden to stare for pleasure even at a pinky of a woman. Areas that are usually covered are forbidden even to glance upon. An important person should be careful not even to glance in any case. (MB 7)
Hair of a married woman is ervah and it is forbidden to read opposite it. (ShA2) Even of your own wife. (Rama2) Even if it is just a few hairs. However, hairs that normally come out of the hair covering are not ervah. (MB10 – Rama2) If the din is to cover it, it is ervah even in communities where prutzos go outside without covering their hair. (MB10) This applies also to an unmarried woman who has had relations. If she does not want to cover her hair we cannot force her in this case. (MB11) Since hair is ervah only mid’rabbanan there is no need to turn aside – just close your eyes and say Krias Shema. (MB5)
The Magen Avraham writes that an unmarried girl shouldn’t go without a hair covering unless the hair is braided and not loose. However, others are maykil with this. (MB12)
The Zohar says a woman who does not cover her hair at home causes poverty to her household. She gets a blessing for not allowing a single hair to show in her house. The Mogen Avraham writes that this is a fitting conduct. (MB 14)
The Rama holds that a wig is not ervah (be machmir if it is made of her own hair) and there is no prohibition of her wearing it uncovered in public. In communities where women are machmir not to wear uncovered wigs in public, a woman should not wear an uncovered wig because of maaris ayin. (MB 15)
The singing voice of a Jewish girl from the age of puberty is ervah. The singing voice of a non-Jewish girl is always ervah. (ShA3 – MB17)
If you are stuck in a situation where the voice is unavoidable, learn Torah and daaven nonetheless. Just empower your heart towards kedusha and don’t pay any attention to the voice. (MB17)
If you are used to a certain woman’s voice, it isn’t an ervah for you. Nevertheless, it is forbidden to concentrate on it for pleasure. (Rama 3 – MB 18)
When you say Krias Shema, daaven, or say words of Torah – you form a holy camp opposite you as far as the eye can see that Hashem walks around in – there mustn’t be any ervah there. (MB 19)
The main shita is that the genitals of children are not ervah until a boy reaches age nine and a girl reaches age three. Therefore, a mohel should grasp the baby’s genitals during the beracha. (Rama 4 -MB 24)
Ervah flesh or hair that can be seen beneath sheer cloth is still considered ervah. Since it is covered, closing your eyes is sufficient, you don’t have to turn aside. (MB 25)
Ervah should not be able to be seen even if you can’t see it because of closed eyes or darkness or blindness. Swivel your whole body so that the ervah will be to your side, then you can read Krias Shema, even if the ervah is right next to you. (MB 29,30)
If the ervah is visible through a glass pane, closing your eyes will suffice. (MB29)
Ervah only prohibits speaking words of kedusha but thoughts are allowed. (MB29)