How do I know what volume to set my podcasts at?

Question

Recently I have been making podcasts which consist largely of two to four people talking. I am a complete newbie to the process, and I know little or nothing about audio production.

Volume is something that has always confused me. First, when recording, I can adjust the gain of the microphone input. Then in Audacity I have a million different ways of adjusting the volume. And then ultimately when a listener downloads and plays my podcast, they can adjust the playback volume to their tastes. There are all these stages which impact the final volume, and it seems to me they're all measured relative to each other, and thus lack any kind of objective measure.

I'd like to be consistent among my podcasts, and also hopefully fall in line with some kind of standard so that my podcasts aren't wildly louder or quieter than most other things they listen to.

But it all baffles me because it seems that listening volume is so relative and subjective.

Is there a way to determine a good output volume that isn't just based on trial and error and feel?

Please bear in mind when answering that technical terminology is likely to be too advanced for me to follow.

Answer 1

First, I think we should probably address the concept of volume. The level of a signal has nothing to do with volume. You don't have volume until it is actually put through speakers and you are a hearing it a certain distance from those speakers. Instead you have a "level".

The level is a measure of signal strength and it isn't subjective, but rather based on what the minimum and maximum signal level are for the system you are working with. All the way off is always negative infinity and it works it's way up to 0 which is the ideal maximum signal level for the device to maintain the best quality. However, nobody talks at exactly the same level all the time, so the signal is going to vary some. On most good equipment, it can peak a little above 0db(signal, not volume), but ideally you want to keep the gain set to be at 0 and a little below it most of the time.

Eventually, if the signal gets too powerful, it will exceed what the device can handle and you end up with the waveform getting cut off at the top and bottom. This results in a partially square wave rather than a rounded one and is called clipping.

When setting the gain for recording, your primary goal is to get the majority of the signal as close to 0 as possible (the best possible quality), but you also have to make sure that the signal does not clip, which will render that part of the recording unusable. You also don't want it too much lower than 0db because then the amount of noise that is recorded will increase in relation to the amount of actual signal.

After recording, when you get in to Audacity, it is simply scaling the signal when you adjust the levels. It makes the signal behave as if it is more or less powerful than it originally was so that you can mix it with other inputs. It is all just math being done on the signal and doesn't actually alter the waveform's basic shape, just makes it have a lower amplitude.

The difference between the highest and lowest volumes on a recording is called the dynamic range. Generally, recordings will have a larger dynamic range than will typically make an ideal listening at home. For this reason, a concept called dynamic compression is frequently used. Dynamic compression is a process by which the highest levels can be automatically gained down and the lower levels can be brought up. This results in less of a difference between the highest and lowest signal levels and decreases the dynamic range. This makes a more level volume when someone plays back the audio later.

Ideally the signal will be compressed and then the level raised to be close to 0 to minimize the noise that will be generated in the playback device and maximize the signal level. Then when the device plays it back, it can accurately process the signal to produce output to the speakers at a level that is consistent with other recordings and will have a similar volume to other things that the user was listening to.

That's a pretty quick overview of a lot of what goes in to a recording, but I hope it helps give a deeper understanding of the answer to your question.

Answer 2

One word: Normalization.

Normalization is the process of finding the loudest part of a recording and making it reach the 0 dB level so the loudest part of your recording is as loud as technically corret.

In general, the standard for the highest volume of a recording is defined as 0 dB. Everything which is not as loud will be mentioned as something with a negative value, like -6 dB, which is half the volume of 0 dB.

Aside from the details of leveling, you might want to achieve a recording which is never louder than 0 dB (altough that's technically possible but leads to distortion when you're too fare above), with the loudest part reaching exactly this volume and the lower parts should not be too far away from it, meaning, you might want to maintain a constant volume between -20 dB and 0 dB.

You might already have used gain control on the microphones to make them sound about as loud as each other. If you record each microphone separately, you can use the Normalize filter of Audacity to match the 0 dB for the loudest parts.

You might even want to look into the Audacity Compressor tutorial [1] to see how you can enhance overall volume level of each microphone recording.

If you are set with the result of each microphone, you can mix down the entire project and check if you want additional Normalization of the final project. If each microphone is leveled good, you might not even need this step.

[1] http://manual.audacityteam.org/man/Compressor

Answer 3

In the production chain that you can control, your final audio level is called programme level, as far as I know. There are recommendations for television (at least in Europe) that the programme level should not exceed -9 dB, with exceptions. But for web videos there is no such regulation. As a result you often have to readjust your loud speaker's volume while switching from one YouTube video to the other. Some clips limit themselfes to -9 dB, others use the full range up to 0 dB. "The louder the better" results in what is called the loudness war.

For your podcasts you have to define your own standard, so that at least your own visitors don't have to increase/decrease their speaker's volume while switching from one podcast to the other. My personal rule that I have set for my own videos is:

• I apply a little compression on all voices, just enough to make passages spoken in a low voice as clearly understandable as passages spoken in a louder voice.

• Then I manually remove all peaks, or make them more silent. (Without this, the next step, the normalization, would amplify wrong.)

• Before exporting I normalize the whole track to -3 dB. The level of -3 dB was my personal decision.