How to Improve the Sound of Audio Recorded on your Phone
Your phone’s tiny in-built microphone isn’t exactly professional quality, but there are things you can do to improve the sound of audio once it’s recorded.
The latest crop of smart phones deliver cutting edge photographic and video capabilities which are quite rightly championed by the companies that design them. But what about their audio capabilities? These too are improving and your phone has become an incredibly convenient and serviceable tool for capturing interview audio, video soundtracks, location audio and more.
Here we’re going to assume you’ve already recorded your audio and are looking to improve the results. For example there could be some problems with the space it was recorded in or even a technical glitch. Alternatively you may just want to tweak the overall sound to improve the sonics. Either way we’ll look at various techniques that can be used to repair and improve it, making use of some pretty nifty ERA plugins along the way.
Sometimes, despite your best efforts, you end up with an audio recording that’s unsatisfactory. This can be for a number of reasons but two of the most common are background noise and the acoustics of the space you’re recording in. Understandably the former is typically more significant in outdoor or location recordings and the latter more relevant for indoor spaces. Either way if these aspects are too dominant there are a number of ways to fix things.
For general background noise and to help maintain focus on your subject audio the simplest solution is to use a noise gate. This may seem like a blunt tool, but a noise gate can actually be set to open and close quite smoothly. You can also adjust its level reduction when closed so that some of the background noise remains. This helps achieve a more natural sounding effect. For general low frequency rumbles sometimes all you need is a high pass filter. Start with the frequency at 80Hz and increase this value to taste.
A more advanced and arguably quicker solution to background noise is to use a dedicated noise reduction processor such as the ERA Noise Remover and ERA-D. These plugins work by using a noise profile to address the problematic frequencies and provide an excellent way to clean up the rumble and hiss accompanying outdoor recordings.
The ERA 4 Noise Remover has fewer controls and to get started all you have to do is increase the Processing control. By default the plug in processes the whole frequency range, however you can also use four further Focus settings to direct the processing to specific frequency ranges. Two options address the high and low frequencies specifically and are great for removing hiss and rumble respectively. A third option focuses on reducing the mid range noise, which is where you’ll also find speech. The final option combines the high and low options, leaving the speech area unscathed. Processing tends to reduce the overall level, so use the Output gain to compensate.
Just be aware that the more you turn up the Processing control the more unpleasant artefacts creep in, and these can add a wobbly or watery effect to the sound. Even so, by selecting a suitable Focus option it should be possible to achieve a natural and considerably improved result.
ERA-D is a more complex processor and although noise reduction is achieved with a single knob setting (De-Noise), there are various advanced parameters including noise Type, adaptation speed (Time Constant) and Arftifact Control. The 3 noise Types use different formulas and deliver different processing intensity (Type C is the most subtle). Meanwhile the Artifact Control lets you decide how much to suppress the undesirable sounds created by the noise reduction process.
The most significant advantage of ERA-D is it provides multiband control. So you can adjust the Range (line) and Intensity (dial) of the processing for each band independently and also adjust the crossover frequencies between the bands. Factor in band specific Solo, and you have a more surgical toolset to drill down and remove noise without damaging your focus sounds.
A common problem with sound recordings is undesirable ambience and both the type and amount of ambience can seriously detract from your subject audio. Reducing this with traditional tools such as EQ and gating is virtually impossible. However, dereverberation processing is available - the ERA-4 Reverb Remover and ERA-D both tackle this problem.
Much like Noise Remover, ERA-4 Reverb Remover is the simpler plug in. Once again in addition to the Processing amount you have Focus options to target processing at certain frequency areas. The Low-freq focus is particularly good at removing the dense woolly aspects in room ambience, while the Hi/Low-freq focus is great for more pervasive spaces such as churches.
Meanwhile ERA-D once again provides multiband processing and using its High Intensity setting combined with twin Time Constant settings and Artifact Control it will achieve both more focused and potentially more extreme reverb removal than ERA-4 Reverb Remover.
Sometimes your audio is damaged by unforeseen technical issues such as mic crackles, dodgy leads, hum, overload clipping and so on. Indeed at times you may also find your audio recorder adds digital spikes to the signal which you’ll hear as clicks. Many of these issues can be improved using a simple audio editor. Zoom in on the problem and inspect the waveform - digital clicks for example often appear as vertical lines. Momentary clicks like these can be either cut out completely or reduced in level using the basic editing tools. For the most natural results edit between points where the waveform crosses the horizontal line.
For momentary audio clipping, where the signal has overloaded the input, try ERA-4 De-Clipper. This includes 2 process options and is very simple to use.
Hum can be successfully removed or reduced with a regular EQ plugin and the frequency is often based on the mains frequency (50Hz or 60Hz). Use a frequency analyser (you’ll often find this included with the EQ plug in) to help pinpoint the problem area. A regular high pass filter is a quick fix that will reduce and remove the low frequencies below its cut off frequency. For a more focused solution use a notch filter and reduce just the offending frequency. For more tricky hum and electrical noise a specific plug may do a better job. ERA-4 Noise Remover has a Hum/Buzz setting and will reduce hum in tandem with its other noise suppression function.
Sometimes your audio track can sound a little lifeless and may need some EQ sweetening. This is simply the process of using reasonably gentle EQ to enhance the tonal quality of your recording. Choose a flexible parametric EQ plugin and be ready to cut and boost frequencies by a few dB. For dialogue, adjusting low mid frequencies controls the resonance, and adjusting mid range frequencies affects intelligibility. Higher frequencies can add air or reduce harshness.
Finally, dialogue recordings can suffer from pops, thumps and harsh ess sounds and this is particularly problematic when the microphone is near to the source. Some of these issues you can improve using a regular parametric EQ. For example, try using very narrow peak shaped bands to notch out specific problem frequencies. However, for a quick solution there are various bespoke plug-ins that can address plosives and de-essing. For instant quick results ERA-4 Plosive Remover and De-Esser do a great job. If you want more control, De-Esser Pro offers more accurate frequency selection and allows you to hear which frequencies are being treated and how they are affected.