Recording your lectures? Here are 6 tips for getting better sound quality
If you are one of the growing number of students who record their lectures, there are some simple steps that you can take to improve the sound quality of your audio files.
This was one of the conclusions of our recent study into the recording devices -- apps, digital recorders, external mics etc -- now on the market.
But why bother to record your lectures in the first place?
Quite simply, taking written notes in lectures is not an effective study technique.
For one thing, it is exceptionally difficult to scribble down notes while also attempting to listen to your lecturer; harder than playing chess according to a study conducted by Piolat, Olive and Kellogg in 2005. For another, by taking written notes you aren’t engaging in an active learningprocess, and are consequently unlikely to remember much of the information that was covered.
By contrast, when recording your lectures, you can focus on listening and understanding, safe in the knowledge that everything is being captured to review later, at your own pace.
But what if you get home from your lecture only to discover that large parts of your recording are inaudible due to one of the host of issues that can adversely affect recording quality? To make sure you don’t find yourself in this troubling situation, we’ve put together these six tips, based on our sound testing, for combating the most common issues associated with recordings taken in lecture halls.
1) Make sure to minimise background noise
From fidgety neighbours to the infernal humming of projectors, there are all too many potential sources of background noise in lecture theatres which can spoil an otherwise respectable recording.
One way to combat them is to place your recording device on something soft, rather than directly on the desk. This will absorb the sounds of vibrations caused by scraping chairs, drumming fingers and so on. If you are using an iPhone or iPad, we would also recommend propping the device up at an angle.
Other good strategies include sitting close to your lecturer or the PA system. But be wary of placing your recorder too close to the front due to the fan noise emitted by projectors.
2) Using a mobile device? Watch out for interference
To safeguard your recording against the bleeps and blackouts caused by mobile phones, place your phone on ‘airplane’ mode as soon as you start recording. This is essential if you plan on actually using your phone to take the recording. And it will help save on battery life, which is sometimes an issue when recording with an app.
If you use a digital recorder which is susceptible to mobile interference (our tests found this to be the case with the Olympus DM670 and ME32), we recommend using an external microphone.
3) Noise cancellation: what you should know
Some recording devices and software come with noise cancellation features designed to tune out background noise.
However, our audio experts recommend recording with noise cancellation off because this is your best chance of understanding what was said on playback if your lecturer talks quietly or unclearly. If you choose, you can always apply noise cancellation after taking the recording. But you can’t remove noise cancellation once it has been applied.
4) The pros and cons of centralised recordings
You may want to consider asking your lecturer to record the lecture with a headset or tie-clip microphone, before sharing the recording with you later.
This way, you can be confident that their speech will be crystal clear on playback. Which is ideal if you need a polished recording that can be shared with a wider audience than the students in attendance.
However, you should be aware that with this method, any questions or comments made from the lecture floor will come through indistinctly, if at all.
5) Using an Android device?
During our testing we found that the quality of internal microphones built in to Android devices varied considerably.
On one end of the scale, recordings taken using the Kindle Fire HDX were slightly marred by high-frequency ‘hissy’ sounds, but broadly comparable in quality to the non-Android devices that we tested.
Recordings taken with the Sony Xperia SP, meanwhile, were noticeably noisier, which would be a problem if you were sitting near the back of a quiet lecture.
Worst of all was the recording quality provided by the Nexus 5, which only provided serviceable recordings when used at the front of the lecture theatre.
6) Using your laptop?
If you will be recording with your laptop, we recommend using an external microphone such as the Samson Go. While not essential in every scenario, this pretty much ensures that you will have an audio file that you can work with.
Until recently, it wasn’t possible to use an external microphone with Android devices, but this changed with the release of 5.0 (Lollipop). Now you can plug an external USB microphone into your Android device, provided its hardware supports USB audio input.
We tried this on the Nexus 5 with a Samson Go and cheap OTG connector cable, and it worked very well. However, it did more than double the battery life expended while recording – from 6% to 13% for a 55 minute recording.
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