How do I make my audio volume consistent?

Check Your Audio Sources

Inconsistent audio levels often stem from using multiple audio sources like microphones, aux inputs, computer audio, etc. Each device outputs audio at different levels. For example, the output level from a microphone is lower than the output from an aux input. Using multiple unmatched sources leads to unpredictable changes in volume.

Common audio sources that can output varying levels include:

Microphones – condenser, dynamic, USB, XLR, wireless

Aux inputs – 3.5mm, RCA, digital
Computer audio – built-in sound card, USB interface
Pre-recorded audio – MP3, WAV, streaming

External mixers, interfaces, and recorders

It’s important to understand the different output levels of each source used. This allows you to plan ahead and adjust levels appropriately when switching between sources.

Use a Compressor

A compressor is an audio effect that reduces the volume of loud sounds or amplifies quiet sounds to even out the volume. It does this by lowering the volume when a signal exceeds a set threshold. Key settings on a compressor include:

Threshold – The volume level where compression starts to take effect.
Ratio – How much compression is applied. A 4:1 ratio means for every 4dB over the threshold, only 1dB of volume increase is allowed.
Attack – How fast the compressor reacts when volume exceeds the threshold.

Release – How fast the compression effect is reduced once volume drops below the threshold.

Compressors make the overall volume more consistent by preventing spikes and raising lower sections. This allows all the audio details to be heard clearly. Compression brings up quiet sounds that may get lost and controls loud sounds that may overwhelm other elements. Using a compressor with a fast attack and medium release works well for evening out volume variations in music and vocals (Source).

Normalize Audio Levels

Audio normalization refers to adjusting the volume of an audio recording so that the loudest peak hits a target level (the norm). This process makes the loudness consistent across different audio tracks.[1] Normalization is done by applying a constant amount of gain to the audio to increase or decrease the amplitude.

There are two main approaches to normalizing audio: during editing and during output. Normalizing during editing means applying normalization while working on the individual audio tracks. This ensures all the tracks are at a consistent level while editing. Normalizing during output applies normalization across the final mixed track to reach the target loudness. This produces a consistent listening level on playback. Many streaming sites like Spotify now use loudness normalization on audio streams to maintain consistency.[2]

The main benefit of normalization is making the perceived loudness consistent across different audio sources. This provides a more enjoyable listening experience. However, excessive normalization can lead to clipping or distortion.

Use Limiters

Limiters are a type of audio dynamic range compressor designed to prevent peaks in volume from exceeding a set threshold. When the incoming audio signal exceeds the limiter’s threshold, the limiter will quickly turn down the volume to prevent clipping or distortion. This allows you to increase the overall volume of the audio while ensuring it does not peak over a certain level.

The main settings on a limiter include the threshold, which is the maximum volume level allowed before limiting kicks in, and the ceiling, which is the maximum level the audio will be turned up to. Typically the threshold is set just below the maximum peak level of the audio, and the ceiling is set at 0 dB so that the entire dynamic range can be utilized without clipping.

Limiters work by having an extremely high ratio, often 10:1 or higher. This means that any audio that crosses the threshold will be turned down significantly, essentially “limiting” the signal from getting any louder. This prevents even very short transient peaks from exceeding the threshold you set. Limiters give you insurance against accidental spikes in volume in order to achieve maximize loudness without distortion.

For more on limiters versus compressors, check out this helpful overview: https://www.izotope.com/en/learn/compressor-vs-limiter.html

Automate Volume

Volume automation allows you to precisely control volume levels over time in your audio track. Rather than applying overall compression or limiting to the entire track, automation allows you to create volume changes at specific points. This is done by drawing volume curves (known as automation envelopes or rides) along the audio waveform in your timeline.

For example, you may want to bump up the volume on just one word or phrase to make it stand out. Or you may want to gradually fade the volume up or down leading into or out of a chorus. Volume automation gives you this surgical precision and flexibility.

Automating volume is especially helpful on vocal tracks, allowing you to smooth out any erratic volume levels and help the vocals sit nicely in the mix. Some best practices for effective volume automation include:¹

Focus on smoothing out significant volume spikes or dips
Avoid over-automating – use a light touch
Automate gradual fades rather than sudden volume jumps

Listen on different systems to ensure your automation sounds good everywhere

With practice, volume automation can take your mixes to the next level by providing precise volume control right down to the syllable.

Use a Loudness Meter

A loudness meter is a different type of audio meter than a traditional peak meter. Peak meters simply show the highest signal level at a given moment. However, our perception of loudness depends on many factors beyond just peak levels. Loudness meters aim to match displays to our subjective impression of loudness.

Modern loudness meters comply with standards like ITU BS.1770 [1] or EBU R128 [2]. These define quantities like integrated (momentary, short term, and long term) loudness measured in LUFS. There are also standards for loudness range and maximum true peak level.

The idea is to target a consistent loudness level, like -23 LUFS integrated loudness, despite variations in peak levels. This helps avoid the “loudness war” and make levels perceptually consistent across diverse content. Loudness meters empower engineers to measure and control loudness in a way that matches how viewers actually hear the audio.

Set Target Loudness

Targeting a consistent LUFS (Loudness Unit relative to Full Scale) level is crucial for maintaining consistent perceived volume across your entire audio project. LUFS measures the integrated loudness over the duration of your audio and allows you to normalize your loudness to a target level.

The most common loudness target is -14 LUFS, which aligns with broadcast standards like ATSC A/85. However, for online distribution like Spotify or YouTube, a slightly lower target of -16 LUFS is commonly used to allow for additional headroom ¹. Some recommend aiming for -18 to -20 LUFS for extra dynamic range and to avoid over-compression ².

In the end, the ideal LUFS target depends on your delivery method and personal stylistic preferences. But choosing a target loudness and normalizing to it ensures your listeners perceive consistent volume across tracks.

Route Stems

Using stems in a mixer allows you to have more control over the volume and processing of different elements in a mix compared to using just a master bus. With stems, you can route the vocals, drums, bass, guitars, keyboards etc. to separate tracks in your mixer. This gives you independent volume control over each stem.

When using just a stereo master bus, it’s harder to change the level of the vocals vs the drums for example. You can only turn the entire master bus up or down. With stems, you can turn the vocal stem up and the drum stem down to rebalance the mix.

Volume balancing across stems is critical. The key is to get the relative balance between stems sounding right, then adjust the master fader for overall loudness. Listen to your mix and identify any stems that are too loud or quiet compared to the others. Turn down stems that are overpowering the mix or turn up stems that are getting lost. Getting smooth, even volume across your stems makes mixing and mastering easier.

Citing the source: https://www.soundonsound.com/techniques/mix-rescue-stem-mixing-mastering

Listen on Different Systems

It’s important to check your audio mix on different speaker systems. The frequency response of speakers can vary greatly depending on size, quality, and type (e.g. headphones vs monitors vs built-in laptop speakers). Listening on different systems allows you to hear how your mix translates. Check for any major tonal or balance issues that only reveal themselves on particular speakers.

Listening at different volume levels is also crucial. While you may do most of your critical mixing at moderate volumes, it’s important to also check how your mix sounds when played back softly and loudly. Boosting the volume can reveal issues like harshness in the high-end or muddy low frequencies. Low volume playback can highlight things like audible hiss or a lack of clarity in quieter parts. By referencing across systems and volumes, you can dial in a balanced mix that sounds great regardless of playback equipment or listening level.

It’s best to focus your mix using high-quality studio monitors or headphones. But always be sure to cross-check on a variety of consumer speakers like built-in laptop or phone speakers, Bluetooth speakers, car stereo systems, etc. This will help ensure your mix translates well to real-world listening environments.

Summary

In summary, there are several key techniques you can use to help achieve more consistent audio volume in your productions.

Using compressors and limiters can help control sudden volume spikes and prevent distortion. Carefully setting target loudness levels and monitoring your audio with high-quality meters will help guide your overall volume. Automating faders over time is another useful approach.

It’s also important to listen back on different systems like headphones, speakers, and in the car, to catch any inconsistencies in how your mix translates. Volume levels that sound balanced in one listening environment may be perceived quite differently in another.

By combining these main techniques, checking your mix on multiple playback systems, and keeping a close eye on your meters, you can create audio with clear, consistent, and professional volume levels.