- Effects basics
- Using the Effects Rack
- Effect categories
- Amplitude and Compression effects
- Delay and echo effects
- Filter and EQ effects
- Modulation effects
- Noise reduction/restoration
- Reverb effects
- Special effects
- Stereo imagery effects
- Time and Pitch effects
- Third-party effects (VST and AU)
- Using the Effects menu
- Presets and favorites
- Review questions
- Review answers
This chapter is from the book
This chapter is from the book
This chapter is from the book
Filter and EQ effects
Equalization (or EQ) is an extremely important effect for adjusting tonality. For example, you can brighten muffled narration by boosting the treble or make tinny, thin-sounding voices sound fuller by increasing the low frequencies. Equalization can also help differentiate among different instruments; for example, bass guitar and a drum kit’s kick drum both occupy the low frequencies and can interact in a way that makes each one less distinct. To solve this problem, some engineers might emphasize the bass’s highs to bring out pick and string noise, whereas others boost highs on the kick to bring out the “thwack” of the beater.
Adobe Audition has five equalizer effects:
Parametric Equalizer
Graphic Equalizer
FFT (Fast Fourier Transform) Filter
Notch Filter
Scientific Filter
Each is used for different purposes that can adjust tonality and solve frequency-response-related problems.
Parametric Equalizer
The Parametric Equalizer offers nine stages of equalization. Five stages have a parametric response, which can boost (make more prominent) or cut (make less prominent) specific ranges (bands) of the frequency spectrum. Each parametric equalization stage has three parameters.
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Caution: In the following exercise, keep monitor levels down as you make adjustments. The Parametric Equalizer is capable of high amounts of gain at the selected frequencies.
The bottom edge of the Parametric Equalizer graph indicates frequency, while the right edge indicates attenuation. The blue line indicates the adjustment the effect will apply; a flat line at 0 dB signifies no adjustment.
Choose File > Open, navigate to the Lesson04 folder, and open the file Drum+Bass+Arp110.wav.
In any Effects Rack insert, click the right arrow, and then choose Filter And EQ > Parametric Equalizer. Start playback.
There are five numbered control points. Each represents a parametric stage. Drag up on number 3 to boost response, or drag down to cut the response. Drag left to affect lower frequencies or right to affect higher frequencies. Listen to the way this changes the sound.
In the area below the graph, there are settings for each control point, with the Frequency, Gain, Q/Width, and the number of the control point. The number is also an enable/disable button.
Drag up, or right on the selected stage’s Q/Width parameter to narrow the range affected by the boost or cut, or drag down, or left to widen the range. Try clicking the stage’s number to toggle that stage on or off.
Load the Default preset to restore the EQ to having no effect. The L and H squares control a low shelf and high shelf response, respectively. This starts boosting or cutting at the selected frequency, but the boost or cut extends outward toward the extremes of the audio spectrum. Past a certain frequency, the response hits a “shelf” equal to the maximum amount of cut.
Drag the H square up slightly. This increases the treble. Now drag it to the left, and you’ll hear that the boost now affects a wider range of high frequencies. Similarly, click the L box to hear how this affects the low frequencies. In the Parameter section for the low and high shelf sections, you can click the Q/Width button to change the steepness of the shelf’s slope.
Reload the Default preset so the EQ has no effect. There are two additional stages, Highpass and Lowpass, which you enable by clicking the HP and LP buttons, respectively. Click those buttons now.
A Highpass response progressively reduces response below a certain frequency (called the cutoff frequency); the lower the frequency is below the cutoff, the greater the reduction. A Highpass filter is helpful for removing subsonic (very low-frequency) energy.
Drag the HP box to the right to hear how it affects low frequencies.
You can also change the filter slope’s steepness, in other words, the rate of attenuation compared to frequency. In the HP panel that displays its parameters, click the Gain menu and choose 6 dB/octave. Note how this creates a gradual curve. Then choose 48 dB/octave to produce a steep curve.
Similarly, listen to the way the Lowpass filter affects the sound by dragging the LP box left or right, and choosing different curves from the Gain menu. Keep this project open for the next lesson.
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The strip along the bottom of the screen has three additional options.
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Constant: Changes the way Q is calculated (the width of the curve). Q is a ratio compared to frequency. Constant Width means the Q is the same regardless of frequency. Q is the most commonly chosen option.
Ultra-Quiet: Reduces noise and artifacts but requires much more processing power and can usually be deselected.
Range: Sets the maximum amount of boost or cut to 30 dB or 96 dB. The more common option is 30 dB.
All of these responses are available simultaneously.
Graphic Equalizer (10/20/30 Bands)
A Graphic Equalizer can boost or cut with a fixed bandwidth at various fixed frequencies. It gets its name because moving the sliders creates a graph of the filter’s frequency response.
There are three versions of the effect, each with more frequency bands and, therefore, more subtlety in the adjustments.
FFT Filter
The FFT Filter is an extremely flexible filter that lets you “draw” the frequency response. The default settings are a practical point of departure. FFT (Fast Fourier Transform) is a highly efficient algorithm commonly used for frequency analysis.
Notch Filter
The Notch Filter is optimized to remove very specific frequencies in an audio file, like a particular resonance or AC hum. However, Audition also has a filter optimized specifically for removing hum, which you’ll try out in Chapter 5, “Audio Restoration.”
Scientific Filter
Scientific Filters are commonly used for data acquisition, but they have audio applications as well. For example, they can help you create extremely steep slopes, narrow notches, ultra-sharp peaks, and other highly precise filter responses.
The trade-off is that this precision can compromise other aspects of filtering (for the technically minded, these include phase shift and delay through the filter). These trade-offs resemble the trade-offs inherent in analog filter technology, however, and some people prefer this kind of sonic “character.”
