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Audio and Prompts Discussions

PCI sound card recommendations
User: kmaclean
Date: 8/13/2007 9:28 am
Views: 6254
Rating: 27

This is a cross post from the Downloads forum (see this link).  Ralph was looking for recommendations for PCI sound cards: 

Hello everyone! This is my fourth contribution to the VoxForge project. Wink I used my nearly-new <a href="" title="Sennheiser PC 131">Sennheiser PC 131</a> headset which has a noise canceling microphone. It should have less spikes than my previous contribution which I made with a cheap Trust microphone.  But I am not happy with the quality of my recordings - I want to improve, I am thinking about buying a new PCI sound card instead of using the onboard sound card. If you have any suggestions about a not too expensive, but good PCI soundcard, please let me know.

--- (Edited on 8/13/2007 10:28 am [GMT-0400] by kmaclean) ---

Re: PCI sound card recommendations
User: Robin
Date: 8/13/2007 9:46 am
Views: 414
Rating: 26

Here's my (cross posted and slightly altered) reply.

No soundcard suggestions, but one other option to consider perhaps: a USB soundcard.

An advantage: same sound system on every computer you work on, even on laptops in which you can never have the same type of card as in your desktop . This is good if you work with speaker dependant speech recognition, because your soundcard can alter your voice so your acoustic model needs to be adapted to the combination mic+card. So your speech recognition solution becomes more portable when you can take your (USB) soundcard with you.

Disadvantages: might be hard to get to work with some programmes (though this will only come into play under linux I guess), might draw a tiny bit more power on a laptop?

--- (Edited on 8/13/2007 9:46 am [GMT-0500] by Robin) ---

"Terratec Aureon 5.1 USB MKII" - Linux
User: ralfherzog
Date: 8/14/2007 10:52 am
Views: 549
Rating: 30

Hi Robin!

Yes, a USB soundcard is a good idea.  But at the moment, I'm using only one desktop computer, no laptop.  And a USB soundcard might be more expensive than a PCI soundcard.

And sure, I would like to use the soundcard under Windows XP *and* under Ubuntu Linux.  My onboard audio works under Windows XP and under Ubuntu Linux, but the recording quality under Windows XP is much better. This is the reason why I am using Windows XP to create the audio files that I submit to  

I found a one year old discussion about the USB soundcard "Terratec Aureon 5.1 USB MKII", which might be appropriate for Linux: (German language)

This USB soundcard should work under Linux -, but at the moment I don't know whether it provides a better recording quality than my onboard audio (Mainboard: AsRock 939Dual-SATA2).

--- (Edited on 8/14/2007 10:52 am [GMT-0500] by ralfherzog) ---

Re: "Terratec Aureon 5.1 USB MKII" - Linux
User: Robin
Date: 8/15/2007 10:50 am
Views: 308
Rating: 23
It's quite hard to find a site that gives info on both compatibility and quality. This site: should be helpful for compatibility. If a model is supported then check how good it is compared to your current card.

--- (Edited on 8/15/2007 10:50 am [GMT-0500] by Robin) ---

soundcard with 24-bit/96 kHz
User: ralfherzog
Date: 8/16/2007 7:42 pm
Views: 380
Rating: 40
Hi Robin!

Thanks for the tip.  At the moment, I am thinking about buying the sound card "Creative Sound Blaster X-Fi XtremeMusic PCI", but I could see in the wiki that this sound card is *not* supported (unknown chipset, completely new architecture, manufacturer doesn't support the ALSA developers).

So thanks for the tip, now I know more.

The "Creative Sound Blaster X-Fi XtremeMusic PCI" has the advantage that it is possible to record in the quality of 24-bit/96 kHz.  Would it make sense to record in such a high resolution?  You people from say that you are interested in recordings of the quality 16-bit/48 kHz.  But why not use the higher quality if available?

--- (Edited on 8/16/2007 7:42 pm [GMT-0500] by ralfherzog) ---

Re: soundcard with 24-bit/96 kHz
User: kmaclean
Date: 8/17/2007 1:47 pm
Views: 267
Rating: 24

Hi Ralf,

>But why not use the higher quality if available?

This formula calculating audio file sizes is as follows: 

File size in bytes = sample rate (Hz) x  bits (8/16/24) x channels (1,2,...) x seconds / 8

Therefore, if we collect mono audio with a 48kHz sampling rate, at 16 bits per sample, our target release 1.0 corpus of 140 hours of speech would be at least 45 Gig.

48,000Hz * 16 bits* 1 channel *  (140hours*60*60)/8 = 45.06 Gbytes

If we collect mono audio with a 96kHz sampling rate, at 16 bits per sample, our target corpus of 140 hours of speech would be about 90 Gig. 

96,000Hz * 16 bits* 1 channel *  (140hours*60*60)/8 = 90.12 Gbytes

This is just for release 1.0 of the VoxForge English Corpus.  Since we are starting to look at other languages, the storage and bandwidth requirements for moving to a higher sampling rate would be too large at this stage.


--- (Edited on 8/17/2007 2:47 pm [GMT-0400] by kmaclean) ---

--- (Edited on 8/19/2007 9:34 am [GMT-0400] by kmaclean) ---

FLAC instead of WAV - lossless compression
User: ralfherzog
Date: 8/17/2007 5:18 pm
Views: 287
Rating: 22
Hello Ken,

I understand that there are storage and bandwidth requirements.  But what about using the "Free Lossless Audio Codec" instead of WAV?

Take a look at !

"FLAC's main advantage is the reduction of bandwidth or storage requirements, but without sacrificing the integrity of the audio source. [...] FLAC is for efficient packing of audio data[...] FLAC achieves compression rates of 30 - 50% for most music, with significantly greater compression for voice recordings."

Read the last part again: "significantly greater compression for voice recordings", and think about that!  If the compression rate using FLAC would be more than 50% (at 96.000 Hz/16-bit) then we wouldn't need more storage and bandwidth.

I have no experience with FLAC, but this could be worth a thought.  What is your opinion?  Keep in mind: FLAC is *lossless* compression.

Greetings, Ralf

--- (Edited on 8/17/2007 5:18 pm [GMT-0500] by ralfherzog) ---

Re: FLAC instead of WAV - lossless compression
User: kmaclean
Date: 8/18/2007 2:23 pm
Views: 397
Rating: 17

Hi Ralph,

Thanks for pointing out FLAC lossless compression as an alternative to uncompressed WAV, AIFF or raw.

We actually accept LibriVox submissions in FLAC format (no takers yet ...) - see this FAQ.  And the second iteration of the new speech submission app will likely use FLAC rather than WAV, for the reasons you've mentioned.

As an aside, I've not tested FLAC, so I don't know how valid their claims of a 50% reduction in file is, but even a 25% reduction would make it worthwhile.


--- (Edited on 8/18/2007 3:23 pm [GMT-0400] by kmaclean) ---

Submitting FLAC instead of WAV
User: ralfherzog
Date: 8/18/2007 9:49 pm
Views: 1775
Rating: 29
Hello Ken,

Because you accept submissions in the FLAC format, I will try to convert my wav audio files into the FLAC format before zipping them.

A few minutes ago, I have installed a FLAC converter from the following source:

I made a test and converted a wav speech file with the size of 400 kB into a FLAC file.  The result was the size of only 140 kB. Surprised

Greetings, Ralf

--- (Edited on 8/18/2007 9:49 pm [GMT-0500] by ralfherzog) ---

--- (Edited on 8/18/2007 9:53 pm [GMT-0500] by ralfherzog) ---

Re: Submitting FLAC instead of WAV
User: Robin
Date: 8/21/2007 10:28 am
Views: 287
Rating: 30

Apparently you can even export your sound files directly as FLAC from Audacity (depending on your installation and version).

See this link:


--- (Edited on 8/21/2007 10:28 am [GMT-0500] by Robin) ---