@Alue
Only rushing water like the shower really masks mine.
I think that the rushing water of the shower works for you not because it masks/covers/matches your frequency (the frequencies of rushing water are not high, they are pleasant, otherwise they wouldn't be used as sound therapy, they are under your regular pitch), but you do not hear your frequency because showering, with its plethora of sensorial perceptions (the water sounds, the heat of the water, the tactile sensations in almost all the sensors that are in the skin) steals your whole attention.
In order to hear a sound we have to also have part of our attention available for it to get into our consciousness. That is why in a room with a tic tac wall clock we hear it "on and off". When we are focused on something else, we cease to be aware of it, we do not hear it, and when our mind is freed enough again we rediscover the sound of the wall clock.
If you are an experienced driver, the act of driving takes too little of your attention (driving becomes almost a reflex, performed subconsciously) to not leave plenty of mind space for the perception of your permanent T sound).
While driving I have plenty of attention for my thoughts, while showering it's like I have a break from my life, that is all I do, I just "shower", hard for me to think about anything (else).
But that may happen just in my case so those are just my two cents.