for Android aficionados
As the Android smartphone’s market share surges, so does the number of audio-related apps. Here are some of the best—and they’re free.
BSB.BZ: deciBel Sound Level Meter (www.bsb.bz)
While billed as not being up to professional sound level meter standards (remember, we’re dealing with a telephone mic), after calibrating this app I compared the results to a Phonic PAA6 sound level meter and was surprised at how closely they tracked midrange frequencies. deciBel has multiple modes: Slow mode updates the maximum, minimum, and average values every 15 seconds, along a timeline that can be set to 15, 30, 60, or 120 minutes; fast mode updates the reading every second. Exposition mode is a histogram that shows the number of times the device was exposed to particular sound levels since measurements started.
The app’s screenshot function saves the screen image to the phone’s SD card; you can also rotate the image to make for easier viewing when taking some measurements, as the mic is at the bottom of the phone. Calibration involves going to a screen and hitting up/down buttons until the reading matches that of a calibrated meter.
Sure, it has limitations—but having a sound level meter in your phone is very handy. For example, shoot a tone with a consistent output level through your monitors, and you can check that you’re monitoring at the same approximate level every time you fire up your studio.
University of Cambridge: Hertz, the WAV Recorder
Some Android recorders are low-fidelity affairs designed to record phone conversations or Internet radio stations playing on your phone, but Hertz records 16-bit WAV files up to 44.1kHz to the Android’s SD card.
The GUI is Spartan. Enter the filename (or click on a clock button to automatically enter the date/ time as the filename), choose the sample rate (8, 11.025, 16, 22.05, 44.1kHz), then select “Start Recording.” There are no level controls, but for just grabbing samples or rehearsals, most Android mics suffice—especially because you’re recording at 44.1kHz.
If you want to use a real audio interface instead of the mic, Peavey’s AmpLiNK works well (it’s designed for the iPhone, though, so you can’t use the amp sim app with the Android)—yes, you can record electric guitar with full, high-impedance input fidelity. Regardless of whether or not you use an interface, retrieving files simply involves hooking the phone up to USB, and transferring the files from the SD card.
There are many other Android recorders; for more features, check out Virtual Recorder (www. andro-ix.com), which includes a mic preamp control, pitch change, and auto-level. It’s a bit more of a hassle because it saves as .PCM files, but it’s not a big deal to convert them.
Bofinit: SoundForm Signal Generator (https://sites.google.com/site/bofinit/)
Of course you want a signal generator in your pocket—especially one that can generate white and pink noise, sine, square, triangle and sawtooth waves, and impulses. You can specify the waveform frequency by direct numeric entry, or using up/down arrow buttons. Although you can hear the waveform coming out of the speaker, if you want to feed a piece of gear in a more pro manner, you’ll need an interface like the AmpLiNK mentioned above, or a headphone adapter/splitter.
According to specs on the website, the frequency accuracy is about 1% on a Motorola Droid (I used a Motorola Backflip for testing these apps, so yes, they’ll run on older Android operating systems). Waveform purity is reasonably good, although the upper range of harmonically-rich waveforms shows some degree of ringing and artifacts.
One very cool aspect is that the white and pink noise really are random, not periodic; when on the road, I even find the pink noise a welcome sleep aid. I also like the oscilloscope display for your Android mic, so you can more-or-less monitor the results of what’s happening as you feed a signal into a particular piece of gear. And of course, you can always set up an A=440Hz for tuning. What’s not to like?