deciBel dB unit of measure for sound intensity (Alexander Graham Bell)
inverse square law - the loudness of a sound drops off as the square of the distance from the source. 2x as far = 1/4 the loudness, 1/2 as far = 4x loudness
+6 dB is twice as loud, -6dB is half as loud.
dB is a logarithmic or log scale, NOT a linear scale.
+6 dB is twice as loud, +12 dB is four times as loud, +18 dB is eight times as loud, +24 dB is sixteen times as loud.
Basic Rule: Get your microphone as close to the source as you can.
Signal, Noise
S/N ratio
Signal is the sound you want, noise is everything else.
You want a strong, clear signal, and as little noise as possible. That’s a good signal-to-noise ratio.
Measure the dBs of room tone or ambient sound; that’s noise.
Measure the dBs of the voice or other sound you want the audience to hear; that’s signal.
The difference between the two should be as large as possible. Less than 24 dB is pretty much unusable.
Sound is messy, it bounces around. You can't block sound. There is no such thing as a zoom microphone. A 'directional' mic simply hears a little better in one direction than another.
You need to keep the mic close to the signal source, and far away from noise sources.
The mic on the Flip phone is the little hole beside the lens. You need to get that hole as close to the subject's mouth as possible, it doesn't hear very well.
You have to monitor the sound you are recording through headphones.
If your ears are open to the air, your brain is processing everything you hear and eliminating a lot of the noise. When you listen through headphones, you hear exactly what the microphone and recorder are getting, including all the noise.
If you do not monitor sound, you will get unusable sound - and unusable sound means unusable video.
Supplemental Reading: PGSDV 1 How Sound Works, in Course Materials
