View Full Version : how to improve voice record quality?

Oct 3, 2006, 03:06 AM
currently i'm taking some classes where the teachers talk very fast, so i bought a digital voice recorder (the Sony ICD-U50).
the recorder allows me to download the recorded sound files to my computer under the .DVF format. since itunes and no other audio player on the Mac can play this format, i use this program called Switch Sound (http://www.nch.com.au/switch/plus.html) to convert them to .MP3 format so that i'll be able to transfer them to my iPod.

everything is fine except that, there are so much echos and noises, so i need to somehow improve the teachers' voice and reduce those echos and noises. and, of course, finally export to .MP3 format. it would be even greater if it could read .DVF format.
can you guys recommend me some program to do that job?
(i know absolutely nothing about digital audio editing, but i can learn)

thanks in advance!

Blue Velvet
Oct 3, 2006, 03:20 AM
A) Get the machine as close to the teacher as possible, ask their permission if you can put the machine on their desk or...

B) If the recorder can take an external mic, get yourself a small directional microphone to help cut down ambient noise.

The problem is that the microphone in the recorder is what is called omni-directional, picking up sounds from all around with equal sensitivity. It would be hard to clean up the resulting files with software.

Oct 3, 2006, 04:04 AM
Also check you're using the highest quality recording on the device. On lower quality there'll be additional 'bloops' and 'chirps' from the audio compression artifacts.

Alternatively buy a Sony MZ-RH1 Hi-MD recorder and plug in a directional Mic into it. The RH1 is the first Minidisc to be able to talk directly to Macs.

Oct 3, 2006, 04:30 AM
the issue is you have a bad signal to noise ratio. both of BV's suggestions are correct, try them in the order listed.

Oct 3, 2006, 04:40 AM
unfortunately the recorder does not have a microphone jack so i guess i'll have to live with the omni-mic. for better quality at input, yes, i already set it to the best quality, and yes, i came too the class early to pick the best seat. but still, the prof. moves around all the time and the classroom is relatively small, so there are echos all over the place.

is there any hope :confused: i only need to lower down the echos a little bit, and make the prof.'s voice a little more clearer.
i heard Adobe Audition, Sony Soundforge, Cubebase SX.. are the best audio editing softwares. aren't they capable of doing this?

Oct 3, 2006, 06:18 AM
this is something which is solved in the analog stage, not the digital stage. put the recorder on the desk or near where he lectures; getting it closer is the only way to improve your signal to noise.

there are s/w noise reducers, but i don't know how much luck you're going to have with them. "don't record the problem."

Oct 3, 2006, 01:57 PM
i see. thanks :)

Oct 5, 2006, 02:58 PM
hi guys. i need a little more help if you dont mind.

when i listened to the original dvf files on the recorder, it was very listenable, very different from that on the ipod, so i guess it has something to do with the mp3 conversion. maybe because the recording was mono channel (i'm not even sure about this) and the conversion was stereo 128bit, it exaggerates the noises and echos.
also, the dvf files are very small, even at highest quality, they are just a few mb for an hour of recording, while it is tens of mb when converted to mp3.

so can you recommend me a conversion settings for better qualities and sizes?
i have put everything on my website at http://phuongphoto.net/comm315/download/dvf/dvf.html
in the mp3 encoder settings dialog box, there are these settings about CBR, VBR and all.. which i have no clue what they really means :(

Oct 5, 2006, 04:54 PM
if you're recording mono (likely), then don't change it to stereo. it's possible that the program doing the conversion is making the stereo image by messing with the phase.

(if i were at home, i could check the mono compatability -- it doesn't sound phasey on these [crappy] headphones, but it could be)

if those files are a full hour, then it wouldn't surprise me that the mp3 files would be large. full resolution 44/16 stereo files come out to about 10 meg / minute. it's less for mp3, due to the compression and based on the bitrate, but even at 1 meg / minute, a 45 minute lecture will be 45 meg.

btw -- after the text on your page, there's some sort of graphic with a lot of blue and green colors. i couldn't make out what it was supposed to be. :-)

Oct 5, 2006, 08:09 PM
the green/blue stuffs is a screen capture of Switcher's settings dialogue box. probably your browser didnt download and show the full image.
when you get home, can you check these out for me? that would be greatly appreciated!
my goals now are
-better converted qualities
-smaller mp3 sizes

Oct 6, 2006, 03:17 AM
the green/blue stuffs is a screen capture of Switcher's settings dialogue box. probably your browser didnt download and show the full image.
it was a joke about it being an XP screen.

when you get home, can you check these out for me? that would be greatly appreciated!
that's going to be nearly a month.

Oct 9, 2006, 01:34 PM
I don't deal too much with audio and audio conversion, but here's what I say...

I haven't listened to the audio from your site but if you want to make your MP3 files smaller then one thing you could do is use the Variable Bitrate (VBR)

You've been using the constant bit rate which (as the name implies) makes the entire track have the same bit rate...where as the VBR will allow some parts of the track to have a lower bit-rate (saving hard drive space) and other parts of the track to have a higher bit-rate (keeping the quality nice)

At least that's what I understand about video..I'm sure it's the same with audio....

in any case I would set the max bit rate at its maximum (I'm not sure if there's a cutt-off rate for player compatability....) and then set the minimum at the lowest setting, and then of course set the quality at the max....

run a few test, adjusting the low bit rate to improve quality...

under the "sterio Encoding" see if there's an option in the drop down list to be mono...that might help save HD space as well....

What I try and do is keep eveything at it's highest quality no matter how big the file size is...

Like I said, I don't know much about audio...but I'd thought I'd give my $0.02...

Oct 11, 2006, 01:46 AM
your 2 cents really work. i followed what you suggested and now i got smaller files with higher quality. im really really happy now. thanks a lot