What is loudness, and why is it important in podcast audio?

It’s important to have audio that not only sounds good, but also sounds consistent, meaning consistent between various episodes. A listener should not have to adjust the volume after one episode ends and another begins, and they, hopefully, should not have to adjust the volume during an episode, either. This is where the concept of loudness comes in.

It’s important to note that loudness is not the same thing as amplitude. The maximum amplitude of a piece of audio will almost certainly spike higher than the average loudness.

Here is an example.

Measuring Loudness

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Example: Loudness measurement and adjustment of audio.

In the image above, #4 shows the amplitude scale in db. Notice that the amplitude of the waveform frequently spikes above -3db. However, the loudness is much lower than that. #1 shows the short-term average loudness, #2 shows the long-term average loudness, and #3 shows the loudness range (essentially the dynamic range of loudness).

Audio Loudness Target

As your are mastering the audio, you will want to target a particular loudness level. You will also want to keep in mind how much you want the audio compressed, which you will be able to see indicated in the “range” readout pictures above (#3). For podcast audio, it’s good to keep the audio fairly compressed and with a low dynamic range, as it will be listened to in all types of environments—and spoken word does not need the kind of range that music might.

By the way, I am using the WLM plugin by Waves to monitor loudness.

Audio Loudness Standards

For a long time there was no loudness standard—especially in podcasting. Although there is a standard now, it is essentially a recommendation, as there is no organization that regulates the standard. You are free to mix and release your podcast anyway you choose, whether or not it meets that standards. However, it’s a good idea to follow the standard for consistency between your episodes, as well as keeping some consistency with other podcasts.

The standard target loudness for podcasts is -18db. You will notice in the above image that I have mixed this particular podcast episode to a loudness of -16db. I began editing for the podcast in this example before the loudness standard for podcasts was established, and used my own target of -16db. I have continued using that target for this podcast. It’s close to the standard, and will be consistent with past episodes, which really is the most important factor.

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