A tds measurement tells you not much about how healty your drinking water is.
https://www.aquasana.com/info/tds-meter-what-is-it-and-do-you-need-it-pd.html
It tells you more how good your water is for your washingmaschine.
Sure but if it is tinitus a eq wont help, if your ear is just oversensitive at some fr or fr band, a eq could help. I dont know what it is. My left ear is oversensitive in the 4k region, so eq helps.