High Pass vs Low Pass Filter: Your Questions Answered

Noise is an inescapable part of our everyday lives, but when it comes to music, there’s a couple of ways you can block it out. Whether you’re mixing or adjusting your gear, using filters to their full potential can give you great results.

High pass and low pass filters are utilized to attenuate frequencies that are unwanted on your audio tracks, each with its own set of perks.

In today’s guide, we’ll be going over the whole high pass vs low pass filter debate, and how to achieve that crisp, noise-free audio you’re after, so stick around.

What Is a High Pass Filter?

A high pass filter, also known as a low-cut or HPF for short, passes signal frequencies that go above a certain cutoff point that you set while reducing signal frequencies below that point.

Too sciencey? Simply put, an HPF filters out low frequencies, like bass frequencies, and only allows high ones through.

Low frequencies can include the sound of an AC running in the recording room, or any background noise the mic could’ve picked up during recording.

What Is a Low Pass Filter?

Safe to say it’s the opposite of a high pass filter. A low pass filter (high-cut or LPF) filters out high frequencies while letting low frequencies pass beyond a certain cutoff point.

Although they’re not used as often as high pass filters, low pass filters can help push your audio to the next level by eliminating any overwhelming fuzz or hiss in your tracks. It also smoothes the audio and can add depth to it by differentiating between different instruments or vocals.

When to Use a High Pass vs Low Pass Filter

Now that we got our introductions out of the way, let’s dive deeper into when each filter can be used and the effects they can give you when utilized properly.

High Pass Filter

We already mentioned that you can use HPF to eliminate background noise, but what else can you adjust with it? Here are a few examples:

1. Removing environmental and handling noise. How many times have you attended an event only to hear that ear-bleed inducing rustling, fumbling, and scrunching the mic picks up? Or recording your track only to find that it’ll feature a solo by the garbage truck passing by along with the fan operating in your room? Although this type of noise sounds blaring, they’re low-frequency and can be easily targeted with HPF, leaving your audio crisp.
2. Removing P-pops. Also known as the popping noise that most vocalists suffer from while recording, p-pops or plosives can be avoided by using a good microphone or pop filter, as well as other methods. If you still can’t avoid the plosives, a high pass filter can block the low frequencies of the pops. However, this won’t work well if the plosive and vocals are on close frequencies because it’ll end up clipping the vocals out with the pops.
3. Removing unnecessary low frequencies in instruments or vocals. This requires more fiddling than adjusting the entire audio track, but it will reduce any low frequencies that are taking too much headspace and give you a good headstart on editing.
4. Reducing the possibility of feedback. The noise we all dread and fear; mic feedback is the screeching noise that happens when a microphone and speaker form a closed feedback loop. High pass filters can minimize the feedback and save everyone’s ears.

Low Pass Filter

While they aren’t used as much as their counterparts, low pass filters can help smoothen and balance your audio. Let’s take a look at when to use LPFs:

1. Amping up high frequencies. We see your raised eyebrows, but hear us out. Sometimes audio tracks have unique upper harmonics or vocals that seem to need an extra push. You can play around with LPF to add an edge to them and make them pop. Careful not to go too far or it’ll sound screechy.
2. Balancing multiple vocal tracks. When adding multiple vocals to one track, the lead voice and background vocals can easily drown one another. Using low pass filters can help you make the lead voice stand out more while moving the background vocals, well, to the background.
3. Making instruments pop. If your track is cluttered with instruments and vocal layers, making out what is what can be overwhelming when listening to it. You can go in and selectively adjust the high frequencies of the instruments and vocals to make them pop more (or less). Remember that priority goes to the vocals, not the instruments.
4. Creating depth. Just like a painting, audio needs depth to be interesting. If your track has all the vocals and instruments fighting each other for headspace, chances are you’re lacking depth. Using LPF can help you push sounds forward while pushing others back. This creates a nice layered effect that’s pleasing to the ears. This will require a little fiddling on your part, but trust us, it’s worth it!
5. Removing any fuzz or high-frequency noise clogging up your track. This can also be useful when you’re trying to up an instrument but there’s unwanted noise tagging along with it.

That’s A Wrap!

Love it or hate it, getting your audio tracks just right will need some work. However, with the proper implementation of high pass and low pass filters, you’ll be able to get the audio you seek.

Remember that high pass filters are perfect for getting rid of any unwanted background noises, while low pass filters are best suited for smoothing out tracks and adding in extra pizzazz when needed.

Once you’re familiar with what high pass and low pass filters are able to do, your days of suffering from noise and lack of smoothness will be gone.

We highly recommend experimenting with both types to figure out which one you like the most.