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Scientific Discussion / Re: I can hear below 10Hz - am I abnormal?
Last post by Porcus -
I often read that the limits of human hearing is 20Hz–20kHz. To me, this "fact" seems quite ridiculous.

Indeed. I got 11 Hz bass tones with not-too-expensive IEMs. (But, they broke down only a month or so later. Coincidence or not.)
https://hydrogenaud.io/index.php/topic,105844.0.html

My hunch is that when the "20 Hz" was "agreed upon", it was a lower bound for usable frequency. (Hard to make anything usable when you couldn't reproduce to get any use of it without feeling it in your gut more than hearing it with your ears, but with IEMs you can.) 20 to 20k "looks like a nice rule" too. Very scientific ;-)
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Opus / Re: Opus 1.3-rc
Last post by IgorC -
It's expected. Everything lower than 13 kbps is coded to WB(8kHz). Higher than 13 kbps is coded to SWB/FB (12 kHz/20kHz).

That's why earlier I've posted
P.S. Also I suspect that SWB can be pushed down to ~11-12 kbps (at least for speech) because 1.3RC SWB@13.2kbps is on par with an older 1.2.1 FB@16kbps   :o
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Scientific Discussion / Re: I can hear below 10Hz - am I abnormal?
Last post by Lee James -
I don't think I'm hearing harmonic distortion because when I listen to tones down to 20Hz, they continue to get lower, and when I go below 20Hz, they still continue to get lower. I think I can tell the difference between 10Hz and higher frequencies.
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Scientific Discussion / I can hear below 10Hz - am I abnormal?
Last post by Lee James -
I often read that the limits of human hearing is 20Hz–20kHz. To me, this "fact" seems quite ridiculous.

Surely everyone can hear tones below 20Hz? The buzz of machines like refrigerators? The hum of traffic? Airplanes, etc? Most urban areas are saturated with these irritating frequencies, and I hear them all day long. Am I really so unusual?

If I play 20Hz in Audacity, it's very loud, clear, and easily perceived. It fades in strength as I go down through the teens, down to 9Hz, which is feint,  but I can definitely still hear it. I wasn't able to hear 8Hz, but I was listening in a noisy environment and haven't done much testing. Plus, my ears are pretty blocked up with wax and I have tinnitus, so I wouldn't say my hearing was good anyway.

At the upper end, I can't hear much above 10Hz. So to me, the claim that humans can hear 20Hz–20kHz seems perfectly correct if you halve it!
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Opus / Re: Opus 1.3-rc
Last post by ThaCrip -
Conclusion:
1.3RC1@13.2kbps is on par with 1.2.1@16kbps on speech.
That's 20% of bitrate reduction.  Similar bitrate reduction is observed on higher bitrates (16-40+ kbps)

I was briefly playing around with a speech file I got online (my original copy is a 87kbps VBR MP3(tool in Foobar2000 says 'Lavc56.28')) with v1.3RC vs v1.2.1 I noticed I could lower from 14kbps to 13kbps with v1.3RC and things seemed pretty much the same but going to 12kbps and there was a noticeable hit. although bit rates did not exactly scale down the same from 14kbps to 13kbps to 12kbps...

selected bit rate = actual bit rate...
12kbps = 12kbps (noticeable hit to sound quality vs the two below)
13kbps = 14kbps (seemed to be similar to the setting below)
14kbps = 15kbps (seemed to be similar to the setting above)

basically v1.2.1 @ 14kbps (15kbps real bit rate) is better than v1.3RC @ 12kbps (12kbps real bit rate) on the speech file I tested as the main thing is the v1.3RC @ 12kbps is more muffled where as the v1.2.1 @ 14kbps is not (like the v1.2.1 file @ 14kbps sounds closer to the 87kbps MP3 source file than the v1.3RC @ 12kbps does). is this to be expected?

p.s. this was all done on my Klipsch Pro-Media speakers on the PC with Foobar2000 v.1.3.19.
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