How to Remove 60-cycle "hum" from the Doom 64 OST










Introduction:



Both the developer kit and home console versions of the N64 are notorious for bad sound output hardware, resulting in 60-cycle "hum" that crosstalks into the audio feed. Thanks to Aubrey Hodges releasing the Official Soundtrack to Doom 64, we now have the best-sounding version of these level tracks to date, but we can make them even better! This guide will show you how to improve the quality and resolution of the Doom 64 OST level music using Goldwave. The same techniques will work in other professional audio editing programs like Audacity for example.





Step 1:



For the purposes of this guide, I will use track #16 "Voices in the Blood" as the example file to work from. Open the flac file (always keep the best possible quality files on hand) in Goldwave. The trick is to find an isolated section of the 60-cycle noise. In some tracks, this can be tricky as there aren't a lot of silent spots to choose from. For this track, I've already chosen the most silent part for you. Press Shift+E to bring up the marker window and enter the following values as shown in the image below:

d64humremoval-001





Step 2:


After entering in the marker values, the start and finish flags will be set to those time points in the flac file. You can use the scroll wheel on your mouse to zoom into that specific area and make it wider on your screen if you want to. I have done this in the image below to show the new selected area:

d64humremoval-002


Below is the same section of noise magnified many times so you can see the individual peaks and vallies (do NOT do this yourself as it is not part of the noise removal process):

d64humremoval-002


Looking closely, you'll see there are nine pairs of peaks and vallies. I've found this to be a general minimum sample size that Goldwave can effectively use to "learn" the shape of the 60-cycle noise sample. So keep that in mind when performing these noise reduction techniques in the other tracks. At any rate, press Ctrl+C to copy the selected segment into the clipboard Goldwave uses.





Step 3:


Now that we have copied the isolated noise sample into clipboard memory, we need to use it as a noise reduction filter. This will effectively "subtract" the noise from the entire file. So now press Ctrl+A to reselect the entire track, and then click on "Effect" --> "Filter" --> "Noise Reduction" as shown below:

d64humremoval-002


Step 4:




Now in the Noise Reduction window, you'll want to make sure to select "Use clipboard", set the FFT size to 13, and finally set the Overlap to 16x. I've found that these are optimal settings for this particular kind of noise reduction. Below are the circled important changes to set in the Noise Reduction window:

d64humremoval-002


Now press "OK" to have Goldwave apply the noise reduction. Presto! The 60-cycle hum is virtually eliminated, and the resulting effect actually increases the resolution of the track! You'll be able to hear very subtle music notes that had been previously drowned out by the 60-cycle hum. One important thing to note is you CANNOT use the same isolated noise sample from one track and apply it to another's noise reduction. Each track has a unique noise signature, and so you must use an isolated sample taken from each specific track. Enjoy!









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