EQ Is Your Friend

If your home stereo has controls for adjusting bass and treble, then you’re already familiar with a very simple form of equalizing (or EQ). An equalizer lets you control the loudness of different parts of the sound spectrum, called frequencies. For example, if you want to add some resonance to a voice, you might choose to use an EQ adjustment to boost the bass frequencies in the sound. In a sense, an equalizer is just a very refined volume control that allows you to make certain frequencies of sound louder or softer.

A graphic equalizer provides sliders for adjusting the volume of specific frequencies, as measured in Hertz (Hz). Move a slider up, and the sounds within that frequency will get louder; move it down, and they will get softer. It’s important to remember that each slider represents a point on a curve. By moving the sliders, you are reshaping the curve. In other words, frequencies around the slider will be affected also (see Figure 15.10).

The best way to learn how to use EQ is to experiment, ideally with an editing system or mixing board that provides real-time filtering. Consider using an EQ filter in the following situations:

nSweetening or adding richness. With a simple boost to the low or lower mid-range, you can add presence and richness to a voice. Don’t add too much, though, or you’ll end up with a muffled sound.

nMaking speech more intelligible. Raising the mid-range frequencies (2000Hz, or 2kHz) and reducing frequencies below 100Hz will frequently make for clearer dialogue.

Figure 15.10

The frequencies between the slider controls on your equalizer are connected by a curve. Therefore, adjusting one frequency will shift the frequencies in-between. Don’t expect to be able to adjust only the frequencies on each slider.

334 The Digital Filmmaking Handbook, 4E

Too Much of a Good Thing

Because EQ is really just a refined way of adjusting volume, be aware that by increasing some of the frequencies, you can end up increasing the overall volume. Watch your level meter to make sure EQ’d sounds don’t peak or distort.

nWind and mic bumps. Wind and microphone noise (such as the low rumble noises caused by poor mic handling) can be minimized by reducing the low frequencies (60 to 120Hz).

nReducing hiss and other high-frequency sounds. Just as you can eliminate lowfrequency rumbles, you can also eliminate tape hiss and other high-frequency sounds by lowering frequencies above 5kHz.

nSimulating audio sources. You can use EQ to simulate the sound of a voice on a telephone or music from a car radio by rolling off the appropriate frequencies. For telephone voice, boost everything between 400 and 2000Hz and lower everything else. The same effect can be used to simulate a low-quality car radio, by using less extreme values. In other words, keep more of the high and low end than you would for a telephone effect (see Figures 15.11 and 15.12).

Note that to perform good EQ adjustments, you need to be sure you’re listening to your audio on speakers with a wide dynamic range. If you’re using speakers with a poor response at one end of the audio spectrum, you’ll neither be able to hear or correct troubles.

Figure 15.11

With some simple EQ adjustments, you can easily simulate the sound of a voice coming through a telephone.

Figure 15.12

Or you can simulate the sound coming from a radio or car stereo.

Mixing Boards

If you’re going to do a lot of equalizing, it might be faster to EQ your audio as you capture it by running it through a hardware mixing board.

Where’s That Hum Coming From?

If you hear a hum when you play audio, it might have been recorded onto your original source tape; however, there’s also a chance that it might be coming from your system itself. Faulty cables, loose connections, and power supply problems can all add a hum to your audio signal. Before you try to correct a hum with EQ, make sure that your system isn’t the culprit.

Special Filters

There are tons of specialized applications and plug-ins to help you fix any number of problems, from within your editing application, within your sound editing app, or as a stand-alone application. For creating new sounds, embellishing old sounds, and creating special effects, there are a huge assortment of plug-ins that do everything from simulating Doppler effect to changing pitch and tone, to simulating the sounds of instruments and machinery.