Wow, that must be really annoying. I have it at a very high pitch.

I did get it checked out, and inner ear or nerve damage was suggested as a cause. However, they also suggested that poor posture putting strain on the muscles around the neck could also be a factor, and I have noticed it gets worse when I slouch for extended periods. If you haven't investigated this side of things, it might be worth a go.

I was thinking that the 73 Hz tone is rather pleasant compared to the ~13kHz tone I hear/perceive in both ears almost constantly. It used to bother me a lot, now I accept its presence and try to focus on things I'm doing instead. Of course there's no knowing what the 73Hz experience is like when sustained. My high-pitched tone I attribute to a combination of exposure to loud live music and hypertension from coffee (and to a lesser extent alcohol). The intensity and pitch does vary and often something will trigger the start of the tone in the morning, like the sound of the towel hitting my ears when drying my hair. I've recently cut down my coffee intake dramatically.

I think I agree with you. The low D note I hear must be more pleasant than the 13kHz you hear.

I've heard something similar for the past two years, except mine is at 78 Hz, and only in my left ear. As with you, I hear it only when it is extremely quiet. When the room ambient noise is above about 35 dBA, I never hear it.

Also, oddly, it comes and goes over a scale of months, seemingly at random. One day, I'll wake up in my quiet bedroom and hear it, and I'll continue to hear it in quiet environments for a month or two. Then, after those several months, I'll wake up again and find it gone.

I notice a very loose correlation to it abating after a loud weekend, like a weekend spent driving my race car or doing metal fabrication, but otherwise it seems random.

A while back I ran it down with medical professionals, but the gist of that expensive adventure was that it was likely idiopathic. It appears to be of the subjective type rather than objective, but -- long story short -- that's not definitive.

My "solution" for now is to run the ceiling fan at night during the months it's present.

Very similar experience, after a bit of research it was clear the 'global hum' explanation loses out to the much simpler explanation that it's an internal effect.

I too found exposure to loud noise supressed it (e.g. regularly suppressed for a couple of days after nightclubbing), also only 'audible' in very quiet surroundings (even lightly touching an earlobe caused the 'hum' to cut out).

It went away after life got noisier (kids'n'dogs).

How do you know that's the frequency what you hear? Is it because when you add more 73Hz you don't notice it as much as adding other frequencies?

Other nearby tones will sound "out of tune". At least that's how I can find the pitch of my tinnitus.

I "hear" the tone clearly. From that, I found this online tone generator, and experimented until it sounded nearly exactly like what I hear. I grew up around a lot of music, so maybe it's easier for me to pick out a tone.

I have experienced this after a long noisy drive and big change in elevation. For me, was closer to 50 60hz.

How do you know the frequency of what you hear? Is it a guess or measurement?

Another person asked this too. There's obviously no way to directly measure it, since it is simply a perception of something that does not actually exist. I only "hear" it because I have either neurological damage or inner ear damage. But I know musical notes, and it's a D2. A C#2 is too low, and a D#2 is way too high. It might be more like a 72Hz instead of 73Hz (D2), but it's close. It's a "guess" in the same way that any singer might sing any other particular note. I can hum it, in tune with itself, although the sound of my own voice destroys the perception. I can use that tone generator I linked above, starting it and stopping it, and compare until I hit the right note. Just like tuning a guitar by ear. I do have to have absolute quiet to hear it, but I can reliably hear it 100% of the time when in absolute quiet.