4 min read

Introduction

Recording a good podcast is as much about good voice training and delivery, as much as it is about the technology used to record it. As with other things, you only get better with practice.

In this article we will use Linux command line tools and optionally Audacity to create a quick, no-frills podcast with a background music track. The only other GUI-based tool we will manipulate, will be the ALSA Mixer. The mixer has a command-line interface too, but the GUI is intuitive and quicker. The emphasis is on quick turnaround.

If you are the type that attaches a quick voice message to an e-mail for impact, (“We simply must get this done by Friday!!”) then the podcast creation method outlined here should appeal to you.

If you are new to podcasting and audio mixer setups, the next few sections might be tedious. But towards the end of this article, we will see how quickly one can run down these steps so that you spend more time recording your message than wrestling with technology or complicated screens.

The Recording Setup

A stereo headset with a microphone works best for making or listening to podcasts; but do not despair if you have a desktop microphone and a pair of speakers. You can always upgrade your setup later. For now just make sure that the sound from the speakers does not directly reach the microphone and cause feedback.

Place the microphone towards the lower right of your mouth as you speak, away from your nose. This avoids breathing sounds getting captured. Minimizing ambient noise by choosing a quieter time of the day is also a good idea.

Recording Tips

All through the recording and mixing process, there are a couple of things to keep in mind.

First, stay above the noise floor. The signal should be recorded high enough to stay above the background noise and hiss. If your audio signals are like little, beautiful flowers growing in a grassy field, make sure their stalks are tall enough to tower over the field. Else you would lose the flowers in the prickly grass just as your audio signal would be lost in the background hiss and noise.

Second, stay below the clipping or overload level of the audio channels. If your audio channels were like open water canals, then overloading them past the clipping limit would have a similar undesirable effect on your audio experience as a canal overflowing its banks — puddles around your feet or a jarring quality to your sound.

Since sound level is a dynamic quantity, record your audio at a level of around 80% keeping some margin (or headroom) against clipping.

Setting up the Audio Mixer Connections

An audio mixer application helps us record our podcast by allowing us to mix various signal sources in the right proportion. You can bring up the sound mixer from the Linux start menu by getting into the Sound and Video category.

To those who are new to the red and green lights of the Linux ALSA mixer, let us run a quick intro. There are audio signal sources and there are destinations. An audio mixer allows you to route one or more sources after adjusting their relative levels to one or more destinations and achieve your project goal. The project goal might be listening to music — the destination in this case being a pair of headphones or speakers; or it might be a recording device, say, to capture a podcast as we will do presently.

  1. Once the ALSA mixer or Kmix is up, select the Output tab. Make sure the Master output channel as well as the PCM channel is switched on (click over the green lights so they turn on) and their gains — the slider positions — are at the maximum.
    Podcasting with Linux Command Line Tools and Audacity
  2. Briefly, go the Switches tab and click over the LED indicator to switch on the ‘Mix Mono’. We will use this mixing switch to mix the microphone (voice) and the CD (background score) signals to both the monitoring and the recording channels. You can optionally select the ‘Mic Boost’ switch but experiment with your microphone to check if you indeed need it.
    Podcasting with Linux Command Line Tools and Audacity
  3. Now, go to the Input tab. The two input sources that interest us are the ‘Mic’ or microphone for our voice and the CD for our background music score. We need to mix these two signal sources in the right proportion and deliver them to the Capture device. Turn on the green LEDs for the ‘Mic’ and ‘CD’ sources ensuring that their outputs feed into the ‘Mono Mix’ and also to your monitoring headphones or speakers. That way you get to listen to what is being recorded. All other input sources should be off (their corresponding green LEDs should be off).
    Podcasting with Linux Command Line Tools and Audacity
  4. Lastly, turn on the red LED under the Capture slider on the Input tab ensuring that the ‘Mix Mono’ output gets connected to the recording channel.

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