Vocal Recording Basics Part 2: Signal-to-Noise (SNR)
As mentioned in Vocal Recording Basics Part 1, recording technique trumps equipment. The primary tenet of a good, clean-sounding recording comes from a high signal-to-noise ratio. This is the biggest tell for a poor recording, and yet it’s incredibly easy to fix.
Signal-to-noise is the difference between the desired recorded material (e.g., your voice) to the noise level (electrical noise, room echo, noisy cars outside, etc.). The less noise in your recording, the better. You can measure and define the signal-to-noise ratio in decibels, but that’s beyond the scope of this article. Simply listening should be enough to determine a quality recording. Once you learn the difference, you’ll find that a recording with poor signal-to-noise just “feels” sloppy and unprofessional.
Recording equipment manufacturers make a big fuss over the signal-to-noise ratios of their the equipment (they’ll sometimes refer to it as dynamic range). Premium recording devices specify upwards of 110 dB, A-weighted. Expect to pay a hefty price for minor (less than 5dB) improvements in signal-to-noise at the high-end level.
The big secret of electronics is that signal-to-noise ratio doesn’t matter, at least in today’s devices. Using proper recording practices, you only need about 60dB for a professional-sounding recording. Before digital recording came along, reel-to-reel studio master tapes were used as the standard recording format in the music industry. Artist from the likes of Frank Sinatra, The Beatles, Pink Floyd, and Michael Jackson all recorded on reel-to-reel tapes that were state of the art at the time. The very maximum, these tapes had less than 77dB of SNR. FM radio averages less than 60dB SNR, and cassettes tapes were even lower at around 50dB SNR.
Why do professional audio manufacturers wish to sell us mic preamps and analog-to-digital converters with over 110 dB SNR? After all, some of the greatest recordings of all time were made with fewer than 77dB SNR. The lower noise floor is advantageous specialty recording applications, just not for home studio recording.
The Noise That Actually Matters
Self-noise from electronics are not the cause of poor recordings, which means that your recording equipment isn’t the problem. A high noise floor in amateur recording comes from the following:
- Room reverberation (sometimes referred to as “echo”)
- Extraneous noise (e.g., dogs barking, noisy neighbors, and computer fans)
That’s it! If you can conquer those two problems, then you can create professional sounding recordings quite easily. Having a decent microphone helps, but you’d be surprised at how much a difference it makes even recording into your phone. Here’s how to deal with noise.
- Get Closer
Get close to your microphone. Keep your face within five inches of the microphone at all times. As you increase your distance from the microphone, you also decrease your signal level. Get too far away, and the signal (your voice) to noise (ambient sounds) become equal. Our ears and brains cannot easily distinguish between noise and voices that are of equal loudness. You must increase the volume of your voice in the microphone relative volume of your ambient environment.
If you get pops or “plosives” into the microphone, you can turn your head slightly during “p’s” “b’s” and “t’s” or use an inexpensive pop filter.
Speak as if you’re addressing an audience. I’ve lead training sessions and workshops, and the biggest mistake beginners make with recording is speaking too softly. Your voice is the signal and your ambient environment is the noise.
Think of turning your voice up as equivalent to turning your background noise down. If you’re close to your mic and speaking loudly, your environment will be nearly inaudible. It sounds bizarre, but if you’ve never tried it, you’ll be astounded by the difference. This is why you’ll see television interviewers using handheld mics at concerts, parties, red carpet events or anywhere is full of ambient noise. Speak loudly and getting close to the microphone works wonders in even worst environments.
- Record in a Large Room
Contrary to popular belief, larger rooms are preferable for recording. Small sound booths are used in professional studios to acoustically isolate a singer or instrumentalist from louder instruments. In other words, sound booths act as a quiet chamber, not as an acoustically desirable environment. Many home studios set up booths incorrectly thinking that a booth has inherent recording advantages.
The goal here is to eliminate noise in the form of room echo, or reverberation. As you speak, sound bounces off of walls and returns back into the microphone. These acoustic reflections decrease in volume with distance. Therefore, the farther you are from your walls, the lower the noise from acoustic reflections will be.
I’ll mention that there’s a tradeoff between ambient noise level and acoustic reflections. If your largest room has only hard surfaces or has a loud ambient noise level, then you’re better off with a smaller room. Recording in a living room with a blaring TV nearby or with roommates walking around will not suffice. Your quietest room is always your best option, but given a choice, go for a large quiet room over a small one.
- Remove Noise Wherever Possible
This one’s a no-brainer, but you’d be surprised how many things make noise until you start recording. Remove all ticking clocks, unplug any DC transformers, turn off dimmable or fluorescent lights, and get a long cable to get your microphone away from your computer’s noisy fan. Always listen before recording, and keep your ears peeled for anything that might be making noise in the background.
If you can control your physical location, proximity to your microphone and the level of your voice, you can go a long way toward making a professional-sounding recording. Practice these techniques recording into your iPhone and notice what a difference it makes. Step up to using a studio microphone, and the results will be even better. Keep in mind that entry-level studio equipment is good enough to create a professional sounding recording, and focus on making major improvements in your technique, not your gear.