Hiss and Monica - NOT to be reviewed!

These are not by any means meant to go any further than the Audition Room. I downloaded the newest version of Audacity and have been paying with it lately, so I decided to record these: one from the piece I am now practising and another one of a piece that is already up and which can just stay where it is, thank you.. They are by no means good (the B section of the first piece tends to slow down), the piano has certainly not improved and the MP3 recorder is the same old one. What I really am curious about, is if you, Monica (or anuone else with Monica's ears), can now hear any hiss or, worse still, pulsating hiss. One of them was done in one take, while the other one was edited more than somewhat, but I will not now say which one it is.

 

I hopew this finds you better.

Thank you, Monica. I am doing just as you say, so I suppose Audacity still has not perfected the noise filter. Before what was happening (I found this out editing tape hiss from some tapes I had transferred to CD) was that it only filtered the hiss intermittently. Having filtered passaes where only hiss was present, I found out that I was left with silence, then a burst of hiss, followed by more silence, then more hiss.

I suppose I really will need to get a better recorder, but until then I will remain a dormant member, so expect no new submissions for a lonh long time!

 

I agree with Monica's assessment that the hiss is less overall, in the silent parts, but re-appears when you play anything. Since the butterfly is constantly flapping its wings, this effect is more apparent in the Mozart.

Does your recorder have a feature which auto-adjusts its sensitivity to the loudness of whatever you're recording? If so, it would be best to disable it, because (apart from the fact that it would be working against you when you're trying to vary your dynamics), it would be varying the loudness of the hiss. This would confuse Audacity's noise filter, which you will have calibrated to the hiss to be found at the few seconds of "silence" at the beginning or end of the recording. -- At least that seems a plausible explanation for why the hiss is louder when there are notes present.

If the recorder has the ability to record as WAV instead of compressing to MP3 on the fly, it may be worth listening to see if the WAV is less hissy. You can get Audacity to read in as WAV and write out as MP3, perhaps it has a better conversion algorithm than the recorder.

Another experiment worth trying in Audacity is to use its equalizer instead of the noise remover, and to get it to reduce hiss by depressing the high frequencies.

 

I listen with just the speakers and I did not hear the hiss. Due to age, I'm experiencing a fall-off in really high frequencies, though, so it could just be me.

I notice the recordings are 192 kbps, which means you already know that re-exports need to have settings reviewed. (For a while, I could not figure out why my re-exported MP3's were so much smaller than the originals, and then noticed that Audacity was exporting them in 128 kbps.) This is set in the "Export File" dialog, just before the export begins (the "Options" button).
Just a sanity check - you're not recording these at 128 and then exporting them at 192, are you?

 

A good point. Recording directly to mp3 is a no-no, except maybe if it is a real good recorder and you do no postprocessing whatsoever.

Audio editors should probably issue a warning when being fed mp3 data as input. Because they start out with data where information is already lost, and must convert that back to WAV format (they can only work with WAV internally), trying to restore the data which was lost in the mp3 conversion. And then later on, that strange brew will be compressed to mp3 again, adding insult to injury.
I think it is paramount that you record and post-process in WAV, and not convert to mp3 until the final cut is made. Even then, keep a copy of the WAV just in case you need to get back to it later.

 

Well, when I bought mine there was only that model in the shop, I knew no better (the Site actually says, in its guidelines, something about using at least a portable mp3 recorder - maybe that should be clarified for the benefit of future members) and the price was not too high. To be fair it is a voice recorder and, as such, it works quite well.

You know, Stu, I do not know if it records at 128. You might have hit the nail there. I have my settings to export at 192, so that is why the bitrate was that one even in these trial recordings.

I had a whole batch of tapes, recorded, some of them from LPs and which I transferred to CD, with no editing whatsoever, not counting the audible click the media player added at the end of eatch track. The level of tape hiss being fenomenal, I have been redoing them using Audacity (always from WAV to WAV). Some have been quite successful, though if one listens to them with earphones, one can notice a lowering of quality which seems to vanish if listened though speakers. Come to that, I notice hiss becomes inaudible if one keeps a certain distance from the speakers, but try listening with earphones!

What I also do at times is convert mps3 to WAV to write CDs. Maybe my sound equipment is not too good, but to my ears the result seems good. Certainly better than some of the tapes which I had transferred!

 

There is a very strong hiss with a noise gating effect typical from speech recording device: when no sound is detected the gain is decreased automatically and it is reset at the normal level when sound incoming at the microphone is detected again. Note also that speech recording devices may use a format more destructive than mp3. Yourself and your piano are worth a better recorder.

 

Yes, I think we should need to be more specific on this, maybe even list the models in use here (Edirol, Zoom, Tascam...) as recommended.

 

It would be good if you could post both the original file and the edited version together, so we can hear the effect of the noise reduction.

Often I prefer to listen to recordings with some hiss than to things that have had noise reduction applied. As well as removing the hiss, the noise reduction removes some high frequency components of the sound, spoiling the character a little. But I grew up listening to a lot of audio casettes, so I might be less bothered by hiss than people who've grown up in the CD era.

 

Indeed, that is a good idea, Alexander.

I do not find that tapes are terribly noisy and, yes, noise removal does damage the sound. I really only resort to it when it is so hogh that removing it cannot possibly destroy more than the hiss has done. I transferred all my tapes to CD but, unfortunately, I used the computer, so, in the end, on top of the tape hiss, which was not so bad, I ended up with the noise of the fan! Filrering out the fan, I get the normal tape hiss back, but the sound is not quite what it was before. Had I had the original LPs would have been better.

Stu, My little MP3 recorder records at 192 KPs.