Podcast Audio Breakdown: Audio EQ - Equalization

Podcast Audio | Podcast Production
January 21st, 2018

When editing and mixing your own podcast, you have a few tools available to you to make your episode sound the best i can be.

Today we’re covering one of the most common ones – Audio Equalization (EQ).

EQ is a type of signal processing used to increase or reduce the amount of certain frequency ranges in an audio signal.

In podcast mixing this is usually used to correct issues with the recording environment, make up for frequency biases from the microphone, or to correct/improve the speaker’s audio to be more clear or natural sounding.

Frequency Spectrum

This is what we’re working with, the graph shows the gain on the vertical axis, with 0 being at the center. Left to right is the frequency range from 0Hz all the way up to 20 kHz

1-parametric-eq-flatFlat EQ – no difference from the original signal.

EQ Types

When you pull your audio in to whichever DAW (Digital Audio Workstation) – Audition, Audacity, Reaper, etc. – you’ll have a way to apply an effect plugin to the audio. If it’s available, grab a parametric EQ. If not, you’ll probably have a graphic EQ.

Parametric EQ – gives you control over the frequency, bandwidth, and gain. If it’s multiband, it’ll give you’ll have multiple groupings of frequency control vs just one.

Graphic EQ – gives you access to pre-defined frequencies at a pre-defined Q. So you can only adjust the gain of the specific frequencies. If you only have a graphic EQ available to you, you can still match many of the following examples by just emulating the shape of the parametric EQ curve using the faders in the graphic EQ.

20graphic-eqFlat Graphic EQ.

3-graphic-eq-alteredMatch the EQ curves of a Parametric for similar results.

EQ Controls

Frequency: The center frequency to be affected.

Bandwidth (also known as range or Q): how far above and below the set frequency will your EQ will affect. A lower number will have a larger range. A higher number will have a narrow range.

Gain (level): change in dB at your frequency and bandwidth

Subtractive vs Additive EQ

In general, you want to cut before boosting. This helps you know when you’ve fixed the problem. For example, your vocals aren’t clear enough.

Instead of boosting frequencies in the upper ranges to bring it through. First, think about if there is extra frequencies preventing it from coming through on it’s own.

For example, maybe the vocal is actually a bit boomy or muddy, and by cutting some of that low-end and lower-mid range out, then the vocal comes through.

Fixing Problems with EQ

As mentioned earlier you’re usually going to be correcting issues with EQ in a podcast recording.

Usually one of the following:

  • Fixing issues from poor mic placement
  • Fixing issues from the room that you recorded in
  • Correcting the frequency attenuations from the the mic used

Common Issues and How to Fix:

The following EQ settings should be used as a guideline of where to start. Use your ears and make small adjustments in the frequency, gain and Q to determine how to adjust further

Filter out Low-end:

  • use a low pass filter to roll off frequencies below 100 Hz, vocals don’t really occupy that range, so it’s just cluttering up the low end

4-parametric-eq-high-pass

Improve Clarity:

  • Boost 1k – 4k range by a few dB
  • OR
  • Maybe you need to just reduce some mid range in

5-parametric-eq-clarityCut in mid-range, boost 1kHz – 4kHz.

Remove boominess from proximity effect

Proximity effect is the increase in low, bass frequencies caused by having the sound source too close to a microphone.

  • High pass filter to 100Hz to 150Hz
  • Cut a few dB around 200Hz to 250Hz

6-parametric-eq-fix-proximityHigh-pass 100Hz – 150Hz. Cut in 200Hz – 250Hz.

Add Warmth to a Speaker’s voice:

  • Boost 180Hz to 400Hz by a few dB
  • Be careful here, adding to this range can also muddy up a vocal

7-parametric-eq-warmthBoost in 180Hz – 400Hz.

Sibilance:

The hissing “s” sound is from too much sibilance. This is generally in the 5kHz – 7kHz range. To fix this:

  1. Set a narrow bandwidth (high number)
  2. Boost it up about 8 – 10 dB
  3. Sweep the frequency range to find the exact location of the problem frequencies
  4. Cut the gain down for those frequencies until the hissing is smoothed out
  5. Adjust the bandwidth and gain to sound natural

8-parametric-eq-sibilanceCut in 5kHz – 7 kHz range.

Use Your Ears

The visual interface is helpful to use as a reference and the frequencies above are great as a starting point, but be sure to use your ears to confirm that you’re hearing the desired effect.

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