Plosives are a type of consonant sound that are characterized by the vocal tract being blocked so that all airflow ceases briefly and then releases with a burst of sound. These sounds are inherent to human speech and are typically represented by letters such as p, b, t, d, k, and g. When spoken, they create a sharp, popping noise. In the context of audio recordings, plosives are often unintended and can be a source of irritation, as they cause a spike in the sound level and can lead to a distorted audio quality.
The occurrence of plosives in recordings can often be attributed to the mechanics of vocalization intersecting with the sensitivity of recording equipment. Microphones are designed to capture sound waves; however, the intense burst of air produced by plosives creates a pressure that can overwhelm the microphone diaphragm. This results in a loud, low-frequency thump that can detract from the clarity and overall quality of the recording. Even in simpler recording devices like dictaphones, whose uses often include capturing speech in office settings or for personal memos, plosives can still pose a problem.
Understanding and managing plosives is critical for anyone involved in the recording process, whether in a professional studio or a home setup. Techniques to reduce or eliminate the impact of plosives include proper microphone technique, the use of pop filters, and strategic post-processing. In some cases, particularly with lower-quality recordings or those from dictaphone uses, it may be necessary to extract voice from audio and apply specialized cleaning techniques. This process can help isolate and clean up the vocal track, reducing the impact of plosives on the overall audio quality. Addressing the issue of plosives ensures a cleaner, more professional sound in the final audio product, regardless of the recording device used.
Understanding Plosives
In vocal recordings, plosives are a common phenomenon and can significantly impact audio quality. They manifest as abrupt bursts of air caused by certain consonant sounds.
Definition and Characteristics of Plosives
Plosives are speech sounds produced by the vocal tract when airflow is stopped and then released suddenly, typically by the lips, teeth, or palate. They occur in both spoken language and in vocal recordings. Generally, plosives are associated with letters like p, b, t, d, k, and g. They are characterized by a distinct air blast that can cause a low frequency boom when recorded.
- Common Plosive Consonants:
- Bilabial: p, b (lips)
- Alveolar: t, d (tongue and ridge behind teeth)
- Velar: k, g (back of the tongue and soft palate)
Causes of Plosives in Vocal Recordings
Plosives in vocal recordings are primarily caused by the diaphragm of the microphone being hit by the strong burst of air produced by the articulation of plosive consonants. This causes an unintended low frequency boom, resulting in a distorted sound. Their occurrence is more pronounced in close-mic vocal recordings due to the proximity of the sound source to the microphone diaphragm.
- Factors Leading to Plosives:
- Proximity of the mouth to the microphone
- Absence of a pop filter
- Sudden release of airflow during the articulation of consonants
- Microphone’s diaphragm sensitivity
Maintaining an appropriate distance from the microphone and utilizing windshields or pop filters can mitigate the impact of plosives.
Recording Techniques to Minimize Plosives
Effective plosive minimization in recordings hinges on proper microphone choice, placement, and the use of safeguards like pop filters and windscreens. These techniques are critical for ensuring clarity and professionalism in audio production.
Microphone Selection and Positioning
Choosing the right microphone and positioning it correctly are essential steps in reducing plosives. A directional microphone, such as a cardioid or supercardioid, is preferable because it’s less sensitive to sound from the sides and rear, including plosive blasts.
- Microphone Type: Cardioid or supercardioid microphones
- Positioning:
- Distance: 6-12 inches away from the speaker
- Angle: 20-30 degrees off-axis
- Height: Align with the mouth or slightly above
Positioning the microphone off-axis, rather than directly in front of the speaker’s mouth, helps to avoid the direct impact of plosive air blasts. Additionally, keeping the microphone at a distance of 6 to 12 inches from the speaker allows for a buffer zone. Ensuring the microphone is slightly above and angled downwards towards the speaker’s mouth captures the natural tone of the voice while mitigating the force of the plosives.
Use of Pop Filters and Windscreens
Pop filters and windscreens serve as essential barriers between the speaker and the microphone, dispersing the air from plosives resulting in wind noise removal before it reaches the mic diaphragm.
- Pop Filters:
- Construction: Usually made of nylon or metal mesh
- Placement: 2-4 inches from the microphone
- Windscreens:
- Material: Foam that encases the microphone
- Function: Diffuses wind and breath sounds
Pop filters, often made from nylon or metal, should be positioned 2 to 4 inches from the microphone to effectively disperse the blast of air while maintaining vocal clarity. Windscreens, which are foam coverings that fit over the microphone, offer an additional layer of protection, especially useful in outdoor settings where wind noises can trigger plosives. These tools are especially crucial when using a vocal mic, as they preserve the quality of speech and singing by preventing plosive pops from reaching the recording equipment.
Post-Production Solutions for Plosives
In post-production, several tools and techniques are effectively used to manage and remove plosives from audio recordings. The following subsections outline the methods and software typically employed to achieve this.
Editing and Automation Tools
Automation plays a crucial role in diminishing the impact of plosives. Engineers can manually edit waveforms using software like ProTools to reduce the volume of offending plosive sounds. This involves isolating the plosive frequency spectrum in the audio clip and reducing its levels to blend smoothly with the rest of the recording. Automation can fine-tune the moment plosives occur by applying pinpoint volume adjustments in real-time.
- Software Utilized: ProTools, Logic Pro
- Key Technique: Automation volume edits
Equalization and Compression Techniques
Effective equalization (EQ) and compression can mitigate plosives. Using a high-pass filter removes low-frequency rumble, characteristic of plosive noise. It allows frequencies above a certain threshold to pass while attenuating frequencies below this point, which includes most plosive sounds. Dynamic EQ provides a more precise approach, targeting specific problematic frequencies only when plosives occur.
| Technique | Description | Frequency Range |
|---|---|---|
| High-Pass Filter | Attenuates frequencies below a set threshold. | Low-Frequency |
| Dynamic EQ | Adjusts specific frequencies only when plosives occur. | Full Spectrum |
Compression, when set correctly, can reduce the dynamic range of a recording, making plosive sounds less prominent.
Advanced Restoration Software
Specialized restoration software contains modules purpose-built to remove plosives from an audio recording. The RX De-Plosive module is a prime example of such advancements, designed to seamlessly detect and eliminate low-end plosive thumps without affecting the clarity of the dialogue or recording. These tools can often deliver superior results where manual editing and EQ might fall short.
- Application Example: iZotope RX De-Plosive module
- Process: Intelligently detects and attenuates plosive sounds
Impact of Plosives on Listeners and Content Creators
Plosives can significantly affect the clarity of audio recordings and the perception of professionalism in content creation.
Auditory Experience for the Audience
Listeners may find plosive distortions distracting, as they often manifest as abrupt, jarring bursts of sound within a dialogue. These consonant sounds, particularly those like ‘p’, ‘t’, and ‘k’, can interrupt the natural flow of speech, making it challenging for the audience to stay engaged. Sound quality is crucial in audio recordings, and the strength of plosives can detract from the listener’s experience.
Professional Considerations for Podcasters and Engineers
For podcasters and audio engineers, minimizing plosives is a key aspect of producing high-quality content. They require careful attention during both the recording and post-production phases. Proper microphone technique and equipment, like pop filters, are essential to mitigate plosives at the source.
- Recording best practices: Angle the microphone away from the direct path of the breath, reducing the impact of plosive consonants.
- Post-production techniques: Utilize equalization and editing software to remove or soften plosive peaks.
Content creators who successfully manage plosives are likely to present a more polished and professional product, enhancing their credibility in the eyes of their audience.
