Introduction: Why Clean Dialogue Matters

In professional audio production—whether for film, podcasting, voice‑over, or video games—dialogue is the primary carrier of narrative and emotion. Even a single distracting lip smack or an explosive plosive can break the listener’s immersion and undermine the perceived quality of the entire project. Reducing mouth noises and plosives in the recording stage is far more efficient than trying to fix them in post‑production, but even the best‑captured tracks benefit from a combination of smart technique, proper gear, and skillful editing.

This article covers everything from understanding the physics of plosives to advanced spectral editing. Whether you are a seasoned sound engineer or a voice actor setting up a home studio, these techniques will help you achieve cleaner, more professional dialogue tracks.

Understanding Mouth Noises and Plosives

Before diving into mitigation strategies, it is essential to recognize the two distinct types of unwanted sounds: mouth noises and plosives.

Mouth Noises

Mouth noises include clicks, smacks, lip sounds, tongue clicks, and audible saliva. They occur when the speaker’s mouth is dry, when the tongue or lips part suddenly, or when swallowing between phrases. These sounds are usually short, high‑frequency transients that sit in the 2–6 kHz range. They are often unconscious and vary from person to person. A professional voice actor learns to minimize these through practice and hydration, but they can never be eliminated entirely.

Plosives

Plosives are the harsh popping sounds produced when pronouncing stop consonants like P, B, T, D, K, and G. These consonants involve a complete blockage of airflow followed by a sudden release, creating a burst of air. When that burst hits the microphone diaphragm directly, it causes a low‑frequency thump or a sharp transient that can overload the preamp. Plosives are particularly problematic with large‑diaphragm condenser microphones and when the speaker is too close to the mic.

Understanding the acoustic cause of each problem leads to targeted solutions. Many techniques address both simultaneously, but a few are specific to one type.

Microphone Selection and Setup

The choice of microphone and how it is positioned can dramatically affect the prevalence of mouth noises and plosives. Not all microphones are created equal in this regard.

Pick the Right Microphone for the Job

  • Dynamic microphones (e.g., Shure SM7B, Electro‑Voice RE20) are generally more forgiving of plosives because their diaphragms are heavier and less sensitive to low‑frequency bursts. They also have built‑in pop filters or grilles that reduce wind and breath noise.
  • Condenser microphones (e.g., Neumann U87, AKG C414) capture more detail, including high‑frequency mouth noises, but require careful placement and pop protection. A large‑diaphragm condenser is more susceptible to plosives than a small‑diaphragm or shotgun mic.
  • Ribbon microphones (e.g., Royer R‑121) have a natural high‑frequency roll‑off that can reduce sibilance and mouth clicks, but they are fragile and need a dedicated pop filter to protect the ribbon from air blasts.

For dialogue work, a well‑chosen dynamic mic with a cardioid pattern is often the easiest to work with in untreated rooms, while a condenser can deliver superior clarity when the environment is controlled.

Optimal Microphone Placement

Positioning is a cheap and effective tool. The classic rule of thumb is to place the microphone 6–12 inches from the speaker’s mouth, with the capsule aimed slightly off‑axis (45 degrees left or right) rather than directly in front. This off‑axis position reduces the direct airflow from plosives while still capturing clear speech. Tilting the microphone downward so that it points toward the speaker’s chest (instead of their lips) can also help. Many professional voice actors work with the mic at mouth height but angled slightly downward, which also reduces breath noise.

If the talent tends to move their head while speaking, a larger working distance (10–12 inches) gives more margin before plosives hit the capsule. However, too far away introduces room tone and reflections. A good compromise is to combine a pop filter with a windscreen and maintain a consistent distance.

External resource: Shure’s guide to microphone placement.

Pop Filters and Windscreens

Pop filters are the first line of defense against plosives. They work by physically diffusing the burst of air before it reaches the microphone diaphragm. Two types are common:

  • Nylon mesh pop filters: These are the most affordable and widely used. They consist of one or two layers of fine mesh stretched over a circular frame. They effectively break up airflow but can slightly reduce high frequencies, especially if placed too close to the mic.
  • Metal mesh pop filters: Often made of perforated metal, these are more durable and easier to clean. They tend to be less acoustically transparent than nylon and can cause comb filtering if not positioned correctly. Some premium models have a curved shape to further diffuse air.
  • Foam windscreens: These slip over the microphone capsule and work well for reducing wind noise and breath pops in outdoor or high‑airflow situations. However, they can muffle high frequencies, and for indoor dialogue, a dedicated pop filter is usually more effective.

For best results, place the pop filter about 2–3 inches from the microphone capsule, and have the speaker position themselves 2–3 inches from the pop filter. This creates a consistent spacing that minimizes both plosives and mouth noises while preserving clarity. If you still hear plosives after adding a pop filter, try tilting the entire microphone/pop filter assembly slightly to the side.

External resource: Sweetwater’s comprehensive pop filter guide.

Acoustic Treatment and Recording Environment

While not directly related to mouth noises or plosives, the room acoustics influence how much post‑processing you need. A room with excessive reflections or background noise will require aggressive noise reduction, which can amplify artifacts from clicks and pops. Conversely, a well‑treated room allows you to set higher recording levels with less compression, reducing the prominence of mouth noises.

  • Use absorptive panels or vocal booths to reduce early reflections.
  • Place the microphone away from hard surfaces like windows or bare walls.
  • Ensure the room has a low noise floor (turn off HVAC, fans, and appliances).

A quiet environment means you can set lower gain, which reduces the preamp noise floor and the perception of transient mouth sounds. This is especially important when recording dialogue that will later be compressed or limited.

Speaker Technique and Preparation

Even the best microphone and pop filter cannot compensate for poor technique from the talent. Educating the speaker (or yourself) on good habits is essential.

Hydration and Mouth Preparation

Dry mouth produces more clicks and smacks because the lips and tongue stick together. Drinking water at room temperature is the simplest fix. Avoid dairy products, caffeine, or sugary drinks before a session because they can create phlegm or dry out the throat. Some voice actors swear by eating a green apple: the acidity stimulates saliva production, reducing mouth noises. Another trick is to chew sugar‑free gum for a few minutes before recording, then discard it a minute before the first take to clear the mouth.

Vocal Warm‑ups and Relaxation

Tension in the jaw, throat, or shoulders leads to forced speech and more plosives. Simple vocal warm‑ups like humming, lip trills, and tongue twisters help relax the articulators. A relaxed speaker produces smoother airflow, reducing the intensity of plosives and the frequency of involuntary clicks.

Breath Control

Plosives are often worse when the speaker takes a deep breath just before a plosive consonant. Encourage the talent to breathe naturally, and to avoid rushing into the next phrase. A pop filter will help, but controlled exhalation before a “P” or “B” can make a surprising difference. Some engineers ask the speaker to turn their head slightly away from the mic during plosive sounds, though this must be practiced to avoid noticeable changes in tone.

Consistency in Distance and Angle

Head movements change the angle and distance to the microphone, causing variations in plosive intensity and frequency response. Using a boom arm and a visual marker (like a loop of string or a laser pointer) can help the speaker stay on axis. Many voice actors mark the floor with tape to maintain a consistent spot.

Monitoring and Feedback During Recording

What you cannot hear during the take cannot be fixed easily later. Use closed‑back headphones to monitor the live signal and train your ear to catch clicks and pops as they happen. Stop the take, give the speaker feedback, and re‑record the problematic phrase. This iterative approach is far more efficient than trying to edit out every click in post.

Software solutions like Izotope RX can remove mouth noises after the fact, but they also risk creating artifacts if used aggressively. The best practice is to capture as clean a signal as possible, then use processing as a polish, not a cure.

Post‑Production Techniques

Despite best efforts, some unwanted sounds will survive the recording session. Modern audio editing tools offer several ways to clean them up.

Manual De‑clicking

In a waveform editor (e.g., Pro Tools, Reaper, Audacity), you can zoom in on the transient of a mouth click or plosive and either delete the sample, apply a short fade, or use a pencil tool to redraw the waveform. For isolated clicks, this is often the cleanest method. However, it is time‑consuming for long dialogue tracks.

Spectral Editing

Tools like iZotope RX Spectral Editor or Adobe Audition’s spectral display allow you to see unwanted noises as bright spots or streaks in the frequency domain. You can then selectively delete or attenuate those artifacts without affecting the speech. This is particularly effective for high‑frequency mouth clicks that appear as narrow vertical lines.

De‑essers and De‑clickers

Dedicated plugins like iZotope RX De‑click, Waves WLM De‑esser, or FabFilter Pro‑DS can automatically detect and remove plosive transients and sibilance. Set the threshold carefully to avoid removing the natural clarity of consonants. For plosives, a multiband compressor or EQ with a high‑pass filter (cutting below 100 Hz) can tame the low‑end thump. Many engineers use a high‑pass filter at 60–80 Hz to reduce low‑frequency rumble from plosives without affecting voice fundamental frequencies.

Equalization and Compression

After removing the transient, a narrow notch filter at the plosive’s resonant frequency can further reduce the boom. However, be cautious: over‑EQ can make the voice sound thin. Compression will bring up the level of any remaining mouth noises, so it is best to apply compression only after you have cleaned the track.

External resource: iZotope’s guide to removing mouth clicks.

Advanced Techniques: Blending and Finesse

When editing dialogue at a professional level, the goal is invisibility. Sometimes the best approach is to replace a problematic plosive with a similar sound from another take (comping) or to crossfade around it. In film dialogue editing, “room tone” is captured so that small deletions can be masked by space fill. For a click that falls on a sibilant, you might borrow the “S” from a nearby word. This kind of editing requires patience and a good ear, but it produces the cleanest results.

Another advanced trick is to use a de‑clicker that analyzes the audio in real time during recording (some DAWs offer this as an insert effect). If you trust your monitoring, you can apply a light de‑click on the way in, reducing the workload in post. But always record a clean backup track without any real‑time processing.

Putting It All Together: A Workflow for Clean Dialogue

  1. Prepare the talent: Hydrate, warm up, and practice off‑axis mic technique.
  2. Set up the room: Choose a quiet, acoustically treated space. Place the microphone with a pop filter 6–10 inches from the speaker’s mouth, off‑axis.
  3. Monitor closely: Use closed‑back headphones and listen for clicks and pops during the take. Do not be afraid to retake problematic phrases.
  4. Record at moderate levels: Avoid hitting the preamp too hard; leave headroom for post‑processing.
  5. Edit in post: Start with spectral cleaning to remove obvious clicks. Then apply a gentle high‑pass filter to reduce plosive low end. Use a de‑esser if needed, but prefer manual editing for the most transparent results.
  6. Final check: Listen to the entire track with compression and limiting in place to ensure no residual noises are brought up.

By combining preparation, proper gear, and careful editing, you can achieve dialogue tracks that sound natural, professional, and free from distracting artifacts. Every extra minute spent at the recording stage saves ten minutes in post‑production.

External Resources and Further Reading

These articles offer deeper dives into specific tools and case studies. The core principle remains: prevention first, then precise editing, with the goal of preserving the natural timbre of the human voice.