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Sunday, February 26, 2006

How do I get the right volume levels?

  • Direct link to the mp3

    • Special thanks to Doug Kaye of IT Conversations and Paul Figgiani of The Point Podcast and IT Conversations. Although I don’t know them personally, I would not understand audio levels at all without the guidance they have provided to the podcast community.
    • Ironically, the levels in this podcast are just a touch too loud as I peak in some spots. It’s not too bad though and I don’t have time to re-record.
  • Notice how some podcasts are too quiet while others have a nice big sound while others still sound too loud and distorted in spots (especially poppig ps)?
  • Getting the levels right is tricky because on one hand you want to have a nice big loud sound but if you get too loud it distorts or peaks above 0 db.
  • You need a tool for measuring the average levels or RMS levels - root mean square.
  • Higher end editors have RMS Normalize - Peak Pro, Wave Editor (mac, on the PC - Soundforge, Audition
    • Punch in -17.5 db and your done
    • The application boosts levels that are too soft and quites those that are too loud
    • These apps are expensive star at $299 up to $599 (Peak Pro) - get academic discount
  • I don’t have $300 for software - what do I do? 2 free Mac prgrams - one can also work on Windows
  • RMS buddy is one free tool available as a AU plugin on OSX and a VST plugin in Windows - works in Garage Band, Soundtrack Pro
    • Using RMS Buddy
    • Gives a running measurement of RMS levels
  • AudioLeak (Mac) is standalone app that can measure RMS levels of a whole audio file in a few secondes - even of it’s a 60 minute audio
  • How to control this?
    • 1. Manually with mic technique - I turn input levels up 80% of the way, move in close (approx. 8 inches from the mic of to the left side a bit) and speak in a steady voice. If you speak loudly in some spots move your head in the other direction a bit.
    • Limiter - software or hardware. A limiter cuts the volume levels of at a set point like -1db or -0.5db. It doesn’t allow a recording to get louder than this. I use this in recording with garaqge band. Works well.
    • Compressor similar to a Limiter but more gradual. Starts limiting lelvels as they get to a certain threshold - say -12db. This alloes you to boost the average levels without getting too loud. Can be tricky in pratice.
    • Record at lower levels and boost in post using a limiter to assure you don’t get too loud (clip).
  • Even if you take these measures - you may find it’s not right in fact how do you know the levels are right or if you just have your headphone volume too loud or roo soft.
  • You want to shoot for RMS levles of about -15 to -17 db
  • How to boost
    • Otherwise measure, boost and apply limiter
      • Measure say RMS buddy give -24db


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