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Podcasting Hacks by Jack D. Herrington

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Reduce Noise

Hum and hiss are annoying and distracting. Find out where the noise comes from and how you can reduce or remove it completely.

Hum and noise can ruin your recordings and turn off your listeners. What’s even worse is that you are paying for noise [Hack #39] , since a nice, clean signal will compress better. Better compression means a smaller MP3 file, which in turn means reduced bandwidth and disk space costs. Because software noise filtering distorts your sound, you will want to get rid of all the physical noise in your setup before turning to software noise reduction.

Find the Noise Floor

In a recording environment, the noise level is calculated in decibels. The studio’s inherent noise is called the noise floor. The noise floor is the decibels of the noise in the room itself, which is called environmental noise. This also includes the noise of the sound recording system itself, which is called signal path noise. Since fewer noise decibels are better, you will want to lower your noise floor.

You should start by gauging your noise floor’s current level. Then reduce your environmental noise, and then your signal path noise. Gauging your noise floor is fairly simple. You just record through your microphone [Hack #50] a sample of blank sound. Figure 3-8 shows a recording of the noise.

This is one of the few cases where you actually want a flat line.

The next step is to select the whole signal and use the View menu to plot the spectrum (see Figure 3-9).

The noise floor is the ...

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