Re: [Audacity-users] Equalizing volume of several interviews on a track?

 Re: [Audacity-users] Equalizing volume of several interviews on a track? From: Federico Miyara - 2014-01-15 01:00:17 ```Mattie, [Notice I've changed the subject as Gale suggested] 1) Normalizing will shift volume along the track so that the overall maximum will take some rather high value (typically -1 dB from the digital maximum, i.e., 1 or 0 dB). But every portion of the signal will be amplified (or more seldom) attenuated by the same factor, so differences in volume will persist. If for instance you had one interview's maximum at -6 dB and other at -15 dB, then the first one will have its new maximum at -1 dB and thesecond one at -10 dB (both have been amplified by the same 5 dB) Compression, on the other hand, will reduce dynamic range and may not really succeed equalizing volumes. In the example, using a threshold of -12 dB and a comression ratio 2:1, the first interview will have its new maximum at -3 dB (since above threshold -6 dB ends as -6/2 = -3 dB), while the second interview, being below the threshold will be only amplified by 6 dB and will have its new maximum at -15 + 6 = -9 dB. The difference has reduced but volumes are not the same. (Note that for the sake of simplicity I assumed that the maximum was relevant, but it is not necessarily so) 2) If you want to use compression to equalize volumes you should use a rather low threshold, for instance, some value that includes all interviews, say, -25 dB, and a rather high compression ratio, for instance 6:1. This will ensure all interviews are compressed and as the compression ratio is so high, all will have similar --but not identical-- levels. For instance, -6 dB will turn to be -1 dB and -15 dB will turn to be -2,5 dB. While not identical, the difference is hardly detectable. However, high compression ratios will remove almost all dynamic range and the voice will sound dull and probably inexpressive. 3) If you are willing to do some manual work and there are not too many inteviews, you may select that one which has the maximum peak value and use Analyze / Contrast. This tool allows measuring two selections called "foreground" and "background" (names are not important in this case). Assume Foreground is the previously selected one. Press "Measure selection" on the Foreground line. You will get a "volume" in dB. Next select any other interview and press "Meassure selection" on the Background line. You will get another "volume" in dB. And, most importantly, you will get a difference in dB. This is the gain you should apply to the second interview to get the same general volume as the first one. There are some small chances that, if the peak value of the second interview is much louder than its general volume (if someone shouts, for instance), then you get some clipping. In this case some previous compression of that interview might prove useful. You can repeat the process for all interviews. This requires some work, but gives usually better results. If you would like to improve your work even further, you can do some noise removal on each interview to avoid noise fluctuations across interviews (use Effect / Noise Removal). If the interviews have been done with different equipment and in different environments, then you may perform noise removal using a particular noise profile for each interview. Regards, Federico On 14/01/2014 18:38, gale@... wrote: > Hi Mattie, > > This isn't about file size limits. Please use "Compose" if you can and > give a relevant title to your message. > > If you import the files they will be on separate tracks and then > Normalize will give each track the same maximum volume you > choose (as Bob suggests). > > Normalize won't help equalizing the volume of different interviews > if they are all on the same Audacity track. In that case you should > use Effect > Compressor instead. > > > Gale > > > On Mon, 13 Jan 2014 16:49:43 -0800 > bob cavanaugh wrote: >> Use effect normalize. >> >>> On Jan 13, 2014, at 3:10 PM, Mattie Lennon wrote: >>> >>> >>> >>> Hi, >>> I am using Audacity (on Windows XP) to compile a radio programme. I am putting >>> several interviews, which have been recorded at a different volume >>> level, on one track. What can I do to make it all at the same volume? > > ------------------------------------------------------------------------------ > CenturyLink Cloud: The Leader in Enterprise Cloud Services. > Learn Why More Businesses Are Choosing CenturyLink Cloud For > Critical Workloads, Development Environments & Everything In Between. > Get a Quote or Start a Free Trial Today. > http://pubads.g.doubleclick.net/gampad/clk?id=119420431&iu=/4140/ostg.clktrk > *********** ASKING FOR HELP ************* > > When asking for help on this list, please include the following information, so we can > help you properly: > > * What operating system you are using (for example, Windows XP or Mac OS X 10.5.1) > > * Exactly what three digit version number of Audacity you are using (Help > About > Audacity, or Audacity > About Audacity on a Mac computer) > > * If this is a recording problem, what equipment you are recording with, and how is it > connected to the computer? > > Mailing list: Audacity-users@... > To UNSUBSCRIBE, use the form at the bottom of this web page: > https://lists.sourceforge.net/lists/listinfo/audacity-users > ```