Smartphone Audio Recording – Part 3: Setup / by Nigel Rumsey

A diagram showing smartphone connection to lav microphone So now you have your smartphone, microphone, recording app, some earbuds and you're ready to make amazing audio - how do you do that? The first thing to say is the scope of this post is dealing with the recording technique, not interview technique I've a lot to learn in that area - I will give some links to further information at the end.

In case you haven’t read the earlier posts: I'm not an audio expert, I'm in the early stages of learning how to do this. As much as anything this is a good way for me to consolidate what I've learnt. If you disagree with what I'm saying please chip in, I'm always interested to hear from you.

Before You Set Off

Battery: It may sound obvious but make sure your phone battery is fully charged. Also bring your charging lead with you, if you can record while plugged into mains power then even better. If you’re interested in battery backup this review by Martin Shakeshaft may be helpful.

Memory: check you have enough space in your phone's memory for your recording. Recording in WAV format is going to use approximately 10MB per minute. This is where Android users have a huge advantage, many android phones will except a mini or micro-SD card to expand the memory beyond what's built-in to the phone. I generally need to delete some music from my iPhone before recording to ensure there's enough space.

App Settings

There are many very heavy tomes on this subject but here's my brief layman's guide.

File format: Your recording app can save the file in a number of formats. Keeping it simple there are two choices you’re interested in (1) WAV: a lossless format that will give you the best quality and a greater flexibility in the edit. The downside it takes more storage space than (2) MP3: a lossy format, it uses significantly less space and playable on just about every device. Here's an interesting post that gives more info.

Bitrate and quality: The other things your app is going to ask you to set are the sampling rate, which should be 44,100 khz and the bit depth which will be 16 bit. If you want to know more there’s a good article in Wikipedia. This video does a great job of explaining what the sampling rate and bit depth actually are.

The Setup

If you're using the Rode SmartLAV+ and the Rode SC6 adaptor the image above is how your setup should look. If you're using Rode equipment the TRRS plugs are grey and the TRS plugs are black - if that means nothing to you look back at the previous post.

If you only have a Lav microphone - without the SC6 adaptor - you can still record but you won't be able to monitor your recording - which could be considered the audio equivalent of walking a tightrope without a safety net. The key thing would be to monitor your levels so you will at least know a signal is reaching the phone, if not how sweet is sounds.

Before Recording Put your phone in airplane mode. If it rings or you get a text during the recording your recording will be interrupted - from this point on your 'phone' is a recording device only.

The lav needs to be clipped to the interviewee's blouse or shirt about 150mm below their chin - I don't expect you to get a tape measure out but that's roughly what you're aiming for. If possible you want to clip the microphone so that it's not rubbing on the interviewee's clothing if they move around a little - not always easy. This video gives some tips on positioning the Lav, it also shows how much noise brushing the mic during a recording can make.

[embed][/embed] Levels: While recording you're aiming for a high enough level so that you can clearly hear everything you subject is saying, while avoiding any peaking or distortion. The rule-of-thumb seems to have been to aim for an average level of -12db. It's definitely not easy on these small displays to get an accurate idea of the level. It's best to practice a few times so you know the level on the app you're unsung that's going to give you results you're happy with.

a screen shot from Android app Field Recorder

A screen shot from iPhone app Voice Record Pro











Try to get your interviewee chatting while you're setting up apart from anything else if they're a little nervous this will tend to put them at ease. Check you're levels aren't going it to the red. If you're unsure it's best to err on the side of caution. It's easy to boost the level a bit in the edit, however once you've got clipping because the level's too high there isn't much you can do. For more info check out this Transom article.

Once you've finished recording save a copy of the file to a cloud service like Dropbox or GoogleDrive. You're probably going to want to get to wi-fi zone before you do that or you're going to chomp through your data allowance pretty quickly. The important thing is that you don’t start editing until you’ve made a copy which should, ideally, be off of your phone.

As I've said before I'm skimming the surface of what you can do - my aim is to hopefully inspire you to give this a go. The last post in this series, will give a list of information and further resources. However if you're keen to know more now is the place to go. Transom has a fantastic archive of posts on all the subjects I've covered and way more. Transom is also home to the truly inspiring HowSound podcast, it really is essential listening for any inspiring radio producer.

Next week I'll be looking at a few mics you might be interested in if you want to go hand-held and then week 5 will be a wrap up and further resources post.

Part 1: Getting Started Part 2: What you need (Budget)

Enjoy your week and don't forget to listen to some great radio.