Understanding Waveform and Loudness

[InternetStream]

Mostly 2 MB, though it may be 1 MB in a few cases.

Can you guys up that to say 4-5MB? (Which is pretty tiny in 2020...)

You could use a file sharing site such as dropbox, Google Drive, One Drive, SendSpace or similar, and post a link to the file. If you do that, ensure that downloading is enabled for "anyone with the link" or "public".

Something I will have to look into, but not an option right now as my brain is overflowing with issues that need to be fixed already!

[InternetStream]

Tip:
When sharing a large file on a forum, be sure to say in the post how big the file is - people with slow or limited Internet can be quite annoyed by unexpectedly large files,

I exported my .aup as an .mp3. Not sure if that will help you to help me.

Here is a brief recording of KKTX-FM from last night and it matches the screenshots above. (1.3MB)

rMBP2_KKTX_2020-11-22 (sm).zip

It includes the .mp3 plus a screenshot of what things look like in Audacity as I listened to it.

[steve]

Can you guys up that to say 4-5MB? (Which is pretty tiny in 2020...)

It's not tiny when you have thousands of files, thousands of visitors, and you pay for the bandwidth. Audacity is not a business - the software, support, documentation and websites are all provided free of charge (many thanks to those that donate and support Audacity).

[kozikowski]

Nice sounding recorded phone call.

Thanks. Denise and I are ringers. We're both broadcast professionals. Denise was, I think, Music Director at WWDC when they gave Howard Stern his first real broadcast job. We're both in reasonably quiet rooms and we're both wearing headphones. This is not our first rodeo.

That's how I know this works. The music was a mistake. I wanted to see how much stuff I could cram into a single, real-time recording. The recording computer (on the left) had the playback channel left over, so I jacked it into the mixer and played music—badly as it turned out. I should have put Denise on the left and me on the right and mixed it all down later.

Koz

[DVDdoug]

In this screenshot, I would say the blue wave is at about 25% yet the sound meter is showing -6dB.

I think the meter is showing the peaks and you might not see the waveform peaks unless you zoom-in.

The easiest way to check the peak is to run the Amplify effect. i.e. If Amplify defaults to +6dB, your current peak is -6dB (and you can cancel the effect if you just want to check).

Or, the optional ACX Check plug-in will give you the peak, the RMS level, and some other information.

When I listen to this recording from last night with my headphones set at volume = 50% on my MacBook, the volume is a little on the loud side.

That doesn't seem right

Perceived loudness is related to the short-term average (or RMS) and the frequency content. For voice, RMS is a good proxy for loudness but it doesn't take frequency content into account. (Our rears are most-sensitive to mid-frequencies.) There is a loudness measure called LUFS which does take frequency into account. And, there is a Loudness Normalization effect that allows you to set the LUFS loudness. But as-of now, there is no way to simply measure it without using a 3rd-party plug-in.

[InternetStream]

Here is another snippet (attached) of a recording that I did a decade ago... (1MB)

MBP_OffTheRecord_2010-07-25 (sm2).zip

Notice how on this one the blue wave form is much closer to 1.0 than on the previous attachment from last night?

Now I must confess that this one sounds a bit distorted, and it looks like there may have been some clipping, but back to my confusion above...

Why does the recording of KKTX-FM have such a low (i.e. 25%) wave form yet sound so loud in my headphones, yet this "Off the Record" recording have a waveform that is at maybe 85% and the loudness is the same?

Also, the screenshots show something flaky between the blue wave forms and the sound meters....

[kozikowski]

this one sounds a bit distorted

That's because it is distorted. The track has peak clipping or limiting. See at 19.7 seconds, all the wave tips are exactly the same height?

Screen Shot 2020-11-23 at 9.14.57 AM.png (18.03 KiB) Viewed 250 times

The bouncing sound meter isn't measuring high volume sounds because there aren't any high volume sounds. Something in the system squashed them.

I think the meter is showing the peaks and you might not see the waveform peaks unless you zoom-in.

What he said.

Koz

[InternetStream]

this one sounds a bit distorted

That's because it is distorted. The track has peak clipping or limiting. See at 19.7 seconds, all the wave tips are exactly the same height?

Hey, I recorded that sample 10 years ago and was still new to the concept of "clipping".

My point is that why is the wave form so much higher in the "Off the Record" sample (i.e. 85%) compared to the sample I recorded last (i.e. 25%) and yet the seem to have the same "loudness" when I listen to them with my headphones?


To further prove this point, here are 4 screenshots showing the sample I recorded last night...

1st screenshot shows the original wave form

2nd screenshot is me choosing "Amplify"

3rd screenshot is me listening to it after it is amped up - notice the yellow and red

4th screenshot is me listening to it after it is amped up - with another screenshot showing it going red


Questions:
1.) Why is the waveform at 25% yet the "loudness" at volume = 50% is a tad loud? (Anything I recorded on my old MBP at 25% waveform would be very hard to hear...)

2.) If I used Amplify, be default it should NOT clip, so whyis the amped version going into orange and red?

3.) Why is the amped up version so incredibly loud when I listen to it? (I had to adjust my volume to 25% so it is pleasant to listen to.)

[kozikowski]

whyis the amped version going into orange and red?

The colors are not a guarantee of sound damage. They're a warning.

Audacity has a couple of those.

The timeline has View > Show Clipping. If you perform too loud, Audacity will place a red bar in the blue waves at the event.




This tool operates in the subjunctive. Since in the real world, you can't actually go over "0dB" (no more digital bits, right? They're all used up). The best Show Clipping can do is guess at it. "This sound would have created clipping damage had it really, truly wanted to." Back here on earth, that usually means sensing three or more digital values in sequence at exactly 0dB. No sound in nature can do that, so it must be damage.

But wait. There's more. You can go over 0dB as long as you never leave Audacity. Audacity uses 32-bit floating (don't worry about it) internally so that effects, filters and corrections don't create damage accidentally. Say you applied a filter that boosted some musical tones and the waves got too tall when you did that. The next step can be a volume reduction to bring the waves back down and everything is happy. The clipped sound isn't lost. Audacity is just saving it until you decide what you're going to do. If you tried that trick outside Audacity, say in your sound mixer, it would destroy the music.

This also means you have to make sure your Audacity show is "legal" before you make sound files. No red bars.

Koz

[InternetStream]

Koz,

The colors are not a guarantee of sound damage. They're a warning.

Audacity has a couple of those.

The timeline has View > Show Clipping. If you perform too loud, Audacity will place a red bar in the blue waves at the event.

Yes, I am familiar with that option.

This tool operates in the subjunctive. Since in the real world, you can't actually go over "0dB" (no more digital bits, right? They're all used up). The best Show Clipping can do is guess at it. "This sound would have created clipping damage had it really, truly wanted to." Back here on earth, that usually means sensing three or more digital values in sequence at exactly 0dB. No sound in nature can do that, so it must be damage.

But wait. There's more. You can go over 0dB as long as you never leave Audacity. Audacity uses 32-bit floating (don't worry about it) internally so that effects, filters and corrections don't create damage accidentally. Say you applied a filter that boosted some musical tones and the waves got too tall when you did that. The next step can be a volume reduction to bring the waves back down and everything is happy. The clipped sound isn't lost. Audacity is just saving it until you decide what you're going to do. If you tried that trick outside Audacity, say in your sound mixer, it would destroy the music.

This also means you have to make sure your Audacity show is "legal" before you make sound files. No red bars.

That is all good to know, but can someone please answer my questions in my last post at: Mon Nov 23, 2020 12:53 pm

Thanks.