Subject: Re: 60 Hz hum causing problems with speech recognition From: Pierre Divenyi <pdivenyi@xxxxxxxx> Date: Tue, 16 Jun 2009 08:17:08 -0700 List-Archive:<http://lists.mcgill.ca/scripts/wa.exe?LIST=AUDITORY>> This message is in MIME format. Since your mail reader does not understand this format, some or all of this message may not be legible. --B_3327985029_911271 Content-type: text/plain; charset="US-ASCII" Content-transfer-encoding: 7bit Tarun, you have two options: (1) get rid of the ground loop that is quite probably the culprit, or (2) move to Europe where the 60-Hz hum is unknown. -Pierre On 6/16/09 7:43 AM, "Tarun Pruthi" <t.pruthi@xxxxxxxx> wrote: > 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 > --B_3327985029_911271 Content-type: text/html; charset="US-ASCII" Content-transfer-encoding: quoted-printable <HTML> <HEAD> <TITLE>Re: 60 Hz hum causing problems with speech recognition</TITLE> </HEAD> <BODY> <FONT FACE=3D"Verdana, Helvetica, Arial"><SPAN STYLE=3D'font-size:12.0px'>Tarun= , you have two options: (1) get rid of the ground loop that is quite probabl= y the culprit, or (2) move to Europe where the 60-Hz hum is unknown.<BR> <BR> -Pierre<BR> <BR> <BR> On 6/16/09 7:43 AM, "Tarun Pruthi" <t.pruthi@xxxxxxxx> wrot= e:<BR> <BR> </SPAN></FONT><BLOCKQUOTE><FONT FACE=3D"Verdana, Helvetica, Arial"><SPAN STYL= E=3D'font-size:12.0px'>Hi all:<BR> <BR> 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 recordin= g 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 rand= omly at times giving for example clean recordings during speaker enrollment = and noisy recordings in live testing. The problem is even worse on linux whi= ch has given me all kinds of artifacts in the recordings besides the 60 Hz h= um - my guess is that this is most likely because of driver problems.<BR> <BR> So, I have 3 questions:<BR> 1. What is the source of this 60 Hz noise? Powerline? RF interference? I ha= ve tried disconnecting the power cord - it works sometimes, but not always.<= BR> 2. Is there a standard way to get rid of the 60 Hz hum and ensure clean rec= ordings 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 H= z, but has harmonics all over the frequency range.<BR> 3. If this is a well-known problem with sound cards, then why aren't we, sp= eech recognition community, trying to come up with a mandatory compliance st= andard 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 speec= h recognition accuracies, and a wider acceptance of speech recognition.<BR> <BR> Tarun<BR> Senior Research Engineer<BR> Think A Move, Ltd<BR> <BR> </SPAN></FONT></BLOCKQUOTE><FONT FACE=3D"Verdana, Helvetica, Arial"><SPAN STY= LE=3D'font-size:12.0px'><BR> </SPAN></FONT> </BODY> </HTML> --B_3327985029_911271--