Understanding the limitations of a Mac's microphone
Reader Ross Andrus is seeking greater fidelity from his MacBook Air. He writes:
I have a MacBook Air and I’m trying to record me singing and playing guitar with it but it sounds pretty bad. Is there anything I can do to improve its sound?
Yes. At the risk of sounding harsh, you should get a real microphone (or two).
The microphone inside your MacBook Air was designed with speech (and FaceTime) in mind and can be adjusted in only a couple of ways. Go to System Preferences > Sound > Input and you’ll see that you can change the microphone’s gain (its input volume) using the slider that sits between the two microphone icons. Drag the slider to the right and the mic is more sensitive to sound.
You’ll also spy the Use Ambient Noise Reduction option. When this option is enabled, your MacBook will attempt to filter out background noise—the sound of a running fan or high-pitched traffic sounds, for example. This is a welcome feature when you’re using the microphone over a FaceTime call, but it results in poor music recording. The resulting audio will sound thin, boxy, and a little wavery.
I’ve heard of people closing the lid partway or even constructing baffles to “channel” audio to the mic, but honestly this is one of those situations where you’re attempting to tax hardware that simply wasn’t built with this job in mind. Even when recording podcasts I beg guests who wish to use their Mac’s mic to find another way.
And, as I suggested at the top, that way is to obtain a real microphone. For the kind of use you mentioned I’d consider getting two USB microphones and configuring Audio MIDI Setup as I outline in A Tale of Two Microphones. That lets you control the gain of each mic.
Alternatively you can get a little more real by purchasing a USB audio interface—something like Focusrite’s two-input Scarlett 2i2 interface, for instance—and using it with real real microphones like Shure’s SM58 (vocals) and SM57 (instrument).