There could be several reasons why your neighbor is knocking on your wall even when you are quiet and the only house she is joined to. While I can't know the specific situation without more information, here are some possible explanations:
Noise sensitivity: Your neighbor might be sensitive to even minor noises and could be interpreting normal sounds from your house as disturbances. This could be due to various reasons, such as health issues or a heightened sensitivity to noise.
Unintentional noise: It's possible that there is a structural issue between the houses that makes sounds from your home more audible in your neighbor's property. The knocking might not be intentional but rather an attempt to alert you to the inadvertent noise.
Request for quietness: Your neighbor might be knocking to politely request that you keep the noise down. This could be more effective than confronting you directly, as it's a non-confrontational way to get your attention.
Communication barrier: If there's a language barrier or any other reason that makes it difficult for your neighbor to communicate directly with you, she may resort to knocking as a form of indirect communication.
Signals or habits: It's possible that your neighbor has a habit of knocking on walls, and it might not be directed specifically at you. It could be a routine or a nervous habit that occurs randomly.
Signal for emergency or help: In rare cases, if your neighbor is in distress or needs assistance but cannot reach out directly, she might use knocking as a way to signal for help.
To address the situation, consider the following steps:
Observe the pattern: Try to notice if there's any specific time or situation when the knocking occurs more frequently. This may give you some clues about the reason behind it.
Communicate directly: If you feel comfortable, try speaking with your neighbor politely and inquire about the knocking. Express your concern and willingness to resolve any issues that might be causing the disturbance.
Inspect your home: Ensure that there are no unnecessary noises originating from your house. If there's a structural issue causing the noise to carry, you might want to address it to minimize any unintentional disturbances.
Be considerate: Even if you believe you are being quiet, be mindful of your actions and try to keep noise levels to a minimum, especially during late hours or early mornings.
Seek mediation: If the issue persists and communication with your neighbor doesn't lead to a resolution, you may consider involving a neutral third party, such as a community mediator, to help facilitate a conversation and find a solution.
Remember that open communication and empathy can go a long way in resolving such situations amicably.