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  • Writer's pictureCj Bertram

Understanding Audio Phase: Common Issues and How to Fix Them

Updated: May 3, 2023

Have you ever noticed that sometimes when you layer drum samples over live drum recordings, the resulting sound is not as clear as you expected? This could be due to a phase issue.


In simple terms, phase refers to the alignment of sound waves.


When two or more sound waves are in phase, they reinforce each other, resulting in a louder and clearer sound. However, when they are out of phase, they cancel each other out, resulting in a weaker and muddier sound.


Phase issues can occur when recording multiple tracks separately and then layering them together. For example, when recording drums, each microphone records a different aspect of the sound, such as the kick drum or the snare drum. If these tracks are not properly aligned, they can create phase issues. The resulting sound may be thin, weak or hollow, with certain frequencies missing or muffled.


To fix phase issues, you can use a technique called phase alignment. This involves adjusting the timing of the tracks to ensure that the sound waves are in phase with each other. There are various tools and plugins available that can help with this process. By properly aligning the tracks, you can achieve a fuller and more dynamic sound, with all the frequencies properly represented.


How to Fix Phase Issues


To fix phase issues, it is important to first identify the problem. This can be done by listening to the mix and identifying any areas where the sound is weaker or less defined. Once identified,

phase can be adjusted at the recording stage by moving the microphone or adjusting the phase of the recording in the mix. This can be done using a variety of tools, such as phase inversion, delay, or EQ. Most audio plugins have a button that allows you to flip the phase of the track in question. Below are some screenshots showing you what that button may look like. When I was starting out, this was one of the most frustrating concepts to wrap my mind around. I had no clue what this symbol meant, so hopefully this demystifies it for someone else out there. When you start layering in sounds and things don't sound as full, or present as they should, give this a try.


This image shows what the symbol for "phase" in audio looks like.
This image depicts the "phase inversion" symbol on the waves ssl channel audio plugin.

Issues with Phase in Audio


Phase Cancellation


Phase cancellation occurs when two audio signals with the same frequency but opposite phase are combined. This results in a loss of volume and a thinning of the sound. For example, when layering drum samples over live drum recordings, if the phase of the two signals is not aligned correctly, the sound of the drums can become weak and hollow.

A Depiction of positive and negative phase in audio.

Phase cancellation can be heard in various ways, such as reduced bass response, a decrease in overall volume, and a loss of clarity in the sound. It can also cause the sound to become thin and lack depth, making it difficult to distinguish individual instruments or sounds in a mix.


Comb Filtering


Comb filtering occurs when two audio signals with a slight delay and different frequencies are combined. This results in a series of peaks and valleys in the frequency response, creating a comb-like shape. For example, when using two microphones to record the same sound source, if the distance between the two microphones is not equal, the signals can experience comb filtering.


Comb filtering can be heard as a phasing or flanging effect, where certain frequencies are emphasized or canceled out. It can also cause the sound to become thin and unnatural, making it difficult to achieve a full and balanced mix.


To fix comb filtering, it is important to adjust the distance between the two microphones or adjust the delay of one of the signals. This can be done by using a delay plugin or manually adjusting the timing until the comb filtering effect is minimized.


Fixing Phase Issues


Phase Alignment


When aligning drum tracks, it's important to make sure that the transients are lined up correctly. This will ensure that the drums sound tight and punchy. You can use the phase correlation meter in your DAW to check the phase relationship between the tracks. If the correlation is low, it means that the tracks are out of phase and need to be aligned.


Time-Aligning Tracks


Time-aligning tracks is another way to fix phase issues. This involves adjusting the timing of the tracks so that they are in sync with each other. This is particularly useful when layering drum samples over live drum recordings.


Using EQ to Fix Phase Issues


Using EQ to fix phase issues involves cutting or boosting certain frequencies to adjust the phase relationship between the tracks. This is particularly useful when dealing with phase cancellation issues.


When two tracks are out of phase with each other, they can cancel each other out at certain frequencies. To fix this, you can use an EQ to cut the frequencies that are causing the cancellation. You can also use an EQ to boost the frequencies that are being cancelled out to bring them back into the mix.


Conclusion


Understanding audio phase is crucial for any music producer or audio engineer. Phase issues can cause a range of problems, from a loss of clarity and definition to a complete cancellation of certain frequencies. Fortunately, there are several ways to address phase issues and ensure that your recordings and mixes sound their best.


When layering drum samples over live drum recordings, it's important to pay attention to the phase relationship between the two sources. If the phase is off, you may notice a loss of low end or a lack of punch in the drums. To fix this, you can try flipping the polarity of one of the tracks, or using a phase alignment tool like Little Labs IBP or Sound Radix Auto-Align.


In addition to drums, phase issues can also arise when recording multiple sources of the same instrument or when using multiple microphones to capture a single sound. To avoid these issues, it's important to take the time to check for phase problems and address them as needed.


Overall, understanding audio phase is an important part of producing high-quality recordings and mixes. By taking the time to learn about phase and how to fix phase issues, you can ensure that your music sounds its best and that you're able to achieve the results you're looking for.

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