Did you ever wonder why your voice recording seems a little off in many ways when singing on a microphone? The answer is simple: microphones pick up every sound you make when they’re close to your mouth. When speaking or singing, we usually don’t pick up the incidental noises we make. With a microphone, the plosives, sibilance, and other incidental sounds are easily picked up. They sound unpleasant, and that’s when a pop filter comes in handy. So, what does a pop filter do?
Every splash of spit, movement of your lips, and breath you take gets translated into audio signals and gets amplified on a speaker. Every extra air that you release when finishing a sentence, word, and syllable is also picked up. A pop filter blocks those sounds physically by acting as a barrier between your mouth and the microphone.
As the name implies, it filters popping sounds you make while you speak or singing. Place your hand in front of your mouth and say the word “pop”. Can you feel the thick blast of air coming from your mouth? That mass of air can hit the membrane of your microphone and produce an unsightly crumpling and muddy sound.
Thankfully, not all words can produce enough air to create that kind of sound. It only happens when you speak or sing words with plosives and sibilants. Words with plosives generate the popping air sounds while sibilants create the hissing sounds.
What are plosives anyway? I’m glad you asked. Plosives are syllables that have stop consonants. These consonants are t, d, k, g, p, and. Note that these consonants don’t become plosives until they’re used at the end of a syllable. For example, the p in the word cap generates a plosive sound, unlike pie.
The air mass in plosives is generated because using a stop consonant makes you block the airflow using your lips or tongue. The blockage pressurizes the air. And naturally, once you’re done pronouncing the syllable or word, you’ll open your mouth to release the air. This then allows the pressurized air to go out. The pressure of the air has enough force to generate a popping sound.
Sibilants are produced when a person’s stream of air partially blocks to create a hissing sound. Mostly, sibilants require the person to block the airflow in the teeth area using the tongue or lips, which is primarily different from plosives, which is often stopped behind the lips.
Consonants that produce sibilants are th, ch, s, and z and sibilants are often created at the beginning of a word or syllable. For example:
Microphone Membranes and Vibrations
Microphones convert sound into electrical signals by capturing vibrations or disturbances in the air. Most mics do this by using a thin and sensitive membrane.
Try accessing your sound recorder app on your phone. Start recording and point your phone’s microphone towards your mouth. Note that it’s often located inside a small hole in the bottom part of your phone.
Blow air gently on your mic, stop the recording, and listen to the ‘audio you just created. You might already expect it, but it produced a violent windy sound, right? Even if you didn’t actually make a loud racket when you’re blowing, the air hitting the membrane of the microphone made it vibrate so much that it created sound.
If a gentle breeze of air was enough to generate that kind of noise, the pressure in a plosive sound would be much louder, which can be unpleasant to hear.
So to stop this air from hitting the membrane, most microphones have foam covering the membrane. To provide additional protection, most of them have metal mesh to disperse plosive sounds. Unfortunately, the mesh and foam are not enough to completely eliminate air from infiltrating and exciting the membrane.
Because of that, pop filters were created. A pop filter’s design is simple. It’s just a metal, plastic, or wooden ring with a thin mesh material in it. The mesh material varies depending on the manufacturer or preference of the user.
Aside from blocking plosives, it also acts as a noise filter of sorts. Any background noise from where the screen is facing is often stopped or reduced from reaching your microphone.
Also, it can reduce the loudness of our breath. The breathing techniques we learned for singing tend to be faster and louder than your average inhalation and exhalation. Without a filter, anyone can cognize when we gasp for air.
A pop filter can also prevent spit from hitting on your mic. It sounds a bit crude to say this, but we all know that it’s inevitable that we tend to spray some saliva when we sing or speak.
I did say that a pop filter can help with sibilants. Unfortunately, it doesn’t altogether remove it. Unlike air from plosives, hisses are sharper and have more pressure. A loud hiss can easily penetrate through the mesh of a filter and get into your mic. Usually, sibilants and hisses require an additional process called de-essing when recording, which is a very simple task (only two clicks in Audacity and a few more in Audition).
Most microphones nowadays come with a free pop filter. However, the quality of those filters can vary, and most often than not, they aren’t the best option.
I urge you to browse around and try other filters yourself. I recommend:
- Auphonix if you own a Blue Yeti.
- PemoTech if you have tube type condensers.
- Lastly, you can get the all around Stedman Proscreen.