Everything is well recorded and mixed, and all on good quality gear- so why are my tracks so quiet?
Audio compression is an often misunderstood process that lessens the dynamic range between the loudest and quietest parts of an audio signal, i.e. compressing an audio signal’s dynamic range. If you have an audio signal that varies too much in level, whether its instrument or vocal, you can tame it and even the level out to make mixing far easier.
In this article we’ll cover troubleshooting your audio tracks, using compression and limiting to aid your mixing process, and provide you with some audio samples to highlight the difference between compressed and uncompressed audio.
All the gear but no idea
Recording music is (or should be, at least…) a labour of love. With today’s technology, the quality of tools available to most people to record with is staggering.
If you have even a modestly specified home computer, the addition of a good audio interface and some software will equip you to record scores of tracks, add effects, run virtual instruments, and create music to a professional standard.
And yet, when you finish your masterpiece, despite being well recorded and mixed, it just isn’t as loud as commercially available recordings. You compare with CDs from your collection, and try re-mixing to no avail- still, there’s no answer to the question ‘why are my tracks so quiet?’
What causes this problem, and how can it be fixed? Here we’ll aim to answer these questions. Plus, we’ll aim to answer another: ‘do I really want to make my tracks louder?’
It’s all about dynamic range…
No matter what format you intend to master your work to (from digital audio file to vinyl), you are always at the mercy of dynamic range. This is defined as the difference between the smallest and largest possible values of a changeable quantity. In audio, this is the range from the noise floor (the lowest level, where audio is so quiet it is masked by background hiss), to the highest possible level before the audio is distorted.
On analogue recording formats, such as vinyl or tape, when the dynamic range is exceeded, the signal will start to distort, but become increasingly distorted according to how much the limit is exceeded by. This effect, if used mildly, is not necessarily unpleasant.
On digital formats, if the dynamic range is exceeded, the resultant recording will clip in a very nasty, and in audio terms, offensive manner. For this reason, it is crucial that recordings are kept within these limitations.
With me so far? Good stuff.
When you mix a track, you combine many different sound sources, at differing levels. In a typical pop track, for example, the drums will anchor the track, with vocals also forward in the mix. These will create the track’s peaks.
The perceived ‘loudness’ of a track is dictated by the peaks, or more accurately, by the difference in level between the peaks and the rest of the recording. If this difference (the dynamic range of the track itself) is large, then the track will seem quiet, overall. In the difference in level between peaks and troughs is low, however, the track will seem loud.
This is the reason that your tracks are so quiet, even if normalised (normalising increases the level of a digital track so that the peaks are at the maximum level they can be within the dynamic range).
So, how do we ensure that the dynamic range is small?
Audio Compression and Limiting
The main tool for reducing the dynamic range of an audio signal is a compressor. A compressor works by reducing the level of a signal as it passes over a set threshold. As a result, you can set the threshold so that it will only affect the peaks of a recording.
These are reduced by a ratio that is set by the user- typically from 1:1 up to 10:1. A 1:1 ratio will not affect the signal at all, whilst, say, a 2:1 ratio will reduce a 2dB peak to 1dB. A 10:1 ratio will reduce a 10dB peak to 1dB. Many compressors have ratios above 10:1, but above this level, it is generally considered to be a limiter.
A limiter is like a compressor, except that it doesn’t just reduce the peaks above the threshold, it completely flattens them. Rather than reduce the peaks by a set ratio, it simply doesn’t let the peaks pass the threshold at all.
Mastering engineers commonly use both compressors and limiters (usually ‘brick wall limiters’ which have very fast attack times) to reduce the dynamic range of a finished mix. The result is that the resultant mix suddenly has some headroom (available dynamic range).
Normalising this track raises the level of both peaks and lower levels, increasing the overall perceived level. Thus, your track now seems much louder.
Is this a good thing?
Whilst it’s very tempting to start compressing your tracks to achieve the sort of levels you typically hear on commercial tracks, there are some important considerations to make…
Firstly, mastering is an art in itself. Whilst you can get excellent results with easily available software and equipment, simply turning up the ratio, and squashing the life out of your track to make it as loud as possible will not do your music many favours. Music is (well, in most cases… :-/) a dynamic form. It requires light and shade, quiet and loud, to create drama and movement. Removing too much of the dynamic range will remove the drama.
Compressed and Uncompressed Audio Tracks
Download Audio Files here.
Things to note
Audio compression should be used with great care then. Loudness isn’t everything, particularly when it comes at the expense of dynamics. Recently, many artists have begun to reject this trend for loudness in favour of dynamics (Elbow, NIN and many others). You can, after all, just turn the volume up…
However, if you want that pop ‘punchiness’, then limiting and compression is the way to achieve. Most DAW packages now come complete with mastering effects, with which you can compress and limit however you see fit.
Joe is a contributor for the Dawsons Music blog. Specialising in product reviews and crafting content to help and inspire musicians of all musical backgrounds.