Hello Tarun,
I’ve been using my USBpre since 2001
and have been extremely happy with it.
http://www.sounddevices.com/products/usbpremaster.htm
Lloyd
From: AUDITORY -
Research in Auditory Perception [mailto:AUDITORY@xxxxxxxxxxxxxxx] On Behalf Of Tarun Pruthi
Sent: Tuesday, June 16, 2009 10:02
AM
To: AUDITORY@xxxxxxxxxxxxxxx
Subject: Re: [AUDITORY] 60 Hz hum
causing problems with speech recognition
Hi Linda:
I am trying to make a speech command recognizer using a standard
open-source speech recognizer on my laptop. Most of the work I do, is either on
my office desk or home. I guess the sources of noise would be the usual things:
lights, unclean power, wireless signals etc.
Tarun
On Tue, Jun 16, 2009 at 11:57 AM, Linda Seltzer <lseltzer@xxxxxxxxxxxxxxxxxx>
wrote:
What exactly is the experiment you are trying to do or the test that
you
are conducting and where is the recording being done?
> Hi all:
> I have been having a lot of problems lately with 60 Hz humming noise in my
> speech recordings (I will confess that most of my tests have been on
> windows/linux laptops - and my guess is that they probably have much worse
> recording quality than desktops on average - but we live in a mobile world
> now and I have to make it work on laptops). Whenever it is there, it
> causes
> a serious drop in speech recognition accuracy, especially since it comes
> in
> very randomly at times giving for example clean recordings during speaker
> enrollment and noisy recordings in live testing. The problem is even worse
> on linux which has given me all kinds of artifacts in the recordings
> besides
> the 60 Hz hum - my guess is that this is most likely because of driver
> problems.
>
> So, I have 3 questions:
> 1. What is the source of this 60 Hz noise? Powerline? RF interference? I
> have tried disconnecting the power cord - it works sometimes, but not
> always.
> 2. Is there a standard way to get rid of the 60 Hz hum and ensure clean
> recordings for the purposes of speech recognition? The only way I can
> think
> of is to use notch filters at 60 Hz, and some of the harmonics, say 120 Hz
> and 180 Hz, since most of the times it doesn't manifest as a single tone
> at
> 60 Hz, but has harmonics all over the frequency range.
> 3. If this is a well-known problem with sound cards, then why aren't we,
> speech recognition community, trying to come up with a mandatory
> compliance
> standard for sound card manufacterers which ensures that the microphone
> input is not corrupted by 60/50 Hz noise? That should provide a big boost
> to
> speech recognition accuracies, and a wider acceptance of speech
> recognition.
>
> Tarun
> Senior Research Engineer
> Think A Move, Ltd
>
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