De-hiss me..?

[Cori]

http://www.studioae.com/LibriVox/cori/misc/strange-readers.mp3 (7secs, 200Kb-ish)

Any chance a wise sound editor can explain how to decrease the hissy-hum that backs all my recording, ideally in a way I can replicate in future..?

I have Audacity, with a bunch of Fishy plugins, but apart from a bit of Equalisation (which makes my voice richer, but turns hiss firmly to hum), I've not really tried anything out. (Or at least, not anything that worked well.)

[chris.tierney]

The simplest method I know of in Audacity is to select a short section of noise (a second or two is plenty), and select Effects -> Noise Removal. Then click "get noise profile". Then, select the whole file (or, if the hum is only present in part of it, select that part) and do Effects -> Noise Removal again. This time, click "remove noise". This should deal with the background hum and leave your voice alone. If it makes your voice sound funny, you can undo the effect and try again with less noise removal (there is a slider to select the strength of the effect).

Here's your sample with the hum removed using this technique: http://librivox.christierney.org/strange-readers_no-hum.mp3

[Cori]

Thanks, Chris -- somehow, when I do that, I either end up with hiss remaining, or else the 20,000 Leagues Under the Sea effect. I haven't found a good mid-ground, though what you've done is about there.

I don't mind complex methods to achieve the ends, either, if they're numbered for an editing-idiot to follow.

[knotyouraveragejo]

Cori,

I have never been happy with the results with noise reduction in Audacity for voice files (although it works great for removing turntable hum and fry noise when recording from old lps - which I suspect is what it was originally written to do). Here are two cleaned up versions of your file:

http://www.studioae.com/LibriVox/cori/misc/strange-readers-a.mp3

http://www.studioae.com/LibriVox/cori/misc/strange-readers-b.mp3

The first (and better IMO) was done with Nero wav editor while the second was done with Goldwave. Neither of these is free although you can use the evaluation version of GW for sometime (2000 operations which is a lot of files if you only use it to noiseclean!) before it expires. Nero wav editor is part of Nero Ultra (I have v 6 which came as OEM software with a Sony external DVD-R drive I bought a couple of years ago).

I think it best however (if you can identify the source of your hum/hiss) to try to eliminate the background noise in the first place. A couple of possibilities: (1) your sound card (assuming you are not using a USB mic) (2) the power source for your computer (unplug and record while running on battery if a laptop) (3) input level on your mic may be turned up too high

Jo

[Cori]

Hmmm.

This is a non-USB mic ... I simply can't seem to make USBs work with my crotchety old Win98 laptop (it installs the mic fine, Audacity 'sees' the mic ... but when I go to actually record, it gives me a "not a chance, matey!" error. It's not Audacity's fault, but I'm blowed if I can figue out what *is* botching up. Various permutations of mic plugged in / out and program starting order haven't helped a bit.) Battery-power isn't an option, unless I record pieces less than 15 mins long.

The hiss is more or less the same whatever level I record at -- if I set it lower, I need to increase the volume of the recording, and then the Background Noise Monster returns.

Off to look at Goldwave & to see if anyone I know has an uber-Nero (which does sound v. good!) Thanks, Jo!

[sjmarky]

It's much more hum than hiss. This is the file cleaned with SoundSoap2 with the 60hz hum filter on along with broadband for the hiss:

http://homepage.mac.com/marknelson2/Marks_Downloads/stranger-readers.wav

If you have a Mac, then you can remove it for $99 (price for SoundSoap2). (Can't help you with Audacity - don't use it.)

Is this system hum? If so, is your mic connection good and clean?

If not system, is it possible that motor noise from your computer is being transmitted through a desktop to a mic stand? If so, try a mousepad under your mic stand.

[Planish]

I could not hear any hum until I amplified a bit of the tail end by about 36 dB. I do hear the hiss, but it's not that bad.

I was thinking that all of the "cleaned" samples sounded either like a "wind & surf" effect, or else a too choppy, but then on closer listening to the original, it sounded a bit choppy anyway, probably just because of the nature of the words spoken. Lots of Ds, Ps, and Ts.

I tried using an Audacity "gate" effect, which does a pretty good job of eliminating the noise between syllables, but I don't think I've gotten the parameters just right yet. When the noise level is too high, the gate effect it makes it sound really choppy, but I think this sample that Cori posted is a good candidate for a Gate.

When I tried it, I reversed the entire track, applied a gate, then reversed it again and applied the gate again, so that both leading and trailing edges were gated. It wasn't too bad, but again, it might be a matter of getting the parameters like attack and decay times just right. I'm still rather fuzzy on what the frequency parameters do.

Generically, a "noise gate" substitutes silence for any audio below some specified threshold level. It's the sort of thing that speakerphones might use to prevent low-level ambient noise from activating a microphone and causing the listener to hear nothing from the caller.