Podcasting Hacks

Maintain the Gain

Use gain controlling filters to maintain a consistent level throughout your podcast.

When you start your sound editing application and open a sound file, the display that you see is an amplitude graph. The horizontal axis of the graph represents time, and the vertical axis of the graph represents the amplitude of the signal. If the signal almost reaches the top and bottom of the graph, it will be loud, if it’s close to the center of the graph, it will be soft.

Figure 8-17 shows a sound sample in Audacity [Hack #50] . The selected portion is loud, and the other half is relatively quiet in comparison.

The amplitude of a signal is rated in decibels (dB). A soft signal is in the –20 dB range, a loud signal approaches –6 dB, –2 dB signals are very loud, and 0 dB signals are clipped in the digital world.

Using sound tools, you can alter the amplitude of a signal with various filters and effects. You need to keep two key things in mind when you are working the amplitude of a signal. First, you should have a target dB range in mind. For music, I recommend somewhere between –6 and –2 dB. For the spoken word, I recommend –6 to –12 dB. This means that your loudest signal should be no more than –6 dB, and your softest signal that isn’t silence should be at least –12 dB. Of course, these are personal preferences and you should come up with a range that’s comfortable for your show.

Figure 8-17. A loud portion of a signal selected in Audacity

The second thing to keep in mind is ...