Understanding Waveform and Loudness

First off, as I learn more about audio, I hear everyone talk about things like “-6dB” and yet I don’t know what units or the significance of the whol -1.0 to +1.0 scale is when I record.

The blue waves are in percent and there is a relationship between dB and percent. Three important ones: 100% is 0dB and dB (that we use) gets quieter in negative numbers.

50% is -6dB, and the blue waves run out of poop (technical term) at about -25dB. That’s right. The blue waves won’t measure anything quieter than about -25dB. That’s where the graphics turn into a flat blue mush. Quick look at the bouncing sound meters will tell you that sound keeps getting quieter down to -60dB or so and it actually goes way more quiet than that. You can set Audacity to show you the whole thing if you want.

The blue waves actually work out pretty well because most of the important sounds happen in the loudest 25dB.

This is a thing I wrote about the audiobook sound values. This is a real-world measuring system based on a commercial product.

I don’t know how you can have a mismatch between the sound meters and the blue waveforms. I can make up something. If you zoom into the blue waves far enough, you may find a tiny sharp loud sounds that the graphics can’t deal with but the meter is fast enough to pick up.

I’ve never seem them not match. You’re a celebrity unicorn.

Try this.

Genrate > Tone: 400Hz, Amplitude 0.5. any short time > Enter.

That should give you a 50% tall wave and if you play it, a -6dB sound meter.

Does it?