Audacity Forum

Hi,

I'm trying to record an audiobook. on my Vista laptop using Audacity. At some times of day, if I use the line-in headset mike, I pick up what sounds like AM radio signals. The TV and cell phone are off, and the cordless phone is in another room. I don't have a radio.

I do have a USB stand mike, but that's sub-optimal on a laptop, since it picks up every shift of position I make. Is there any way to get rid of the radio signal? Would disabling the wireless card help?

Thanks for any advice.

<<<line-in headset mike>>>

Your laptop almost certainly doesn't have a powerful, high level, stereo, Line-In. If your microphone works, it does have a delicate, sensitive, mono, microphone input.

"Delicate" and "Sensitive" do not get along well if you have a radio station in your neighborhood. Walk around outside. Any tall red and white towers with red lights on top? Your cordless phone with its fractional watt radio transmitter is no competition to a commercial radio station with multiple thousands of watts radiating from one or more efficient antennas. These people can generate problems for over a mile, so you may need to drive around.

Another possibility is you're generating the junk yourself. Do you like to record internet radio stations? Did you leave one running at low volume by accident?

Record a bunch of it without saying anything and then boost the volume with the Amplify tool. See if you can identify it. Borrow a pocket radio and see if you can find the same show.

<<<At some times of day>>>

What times exactly? Radio stations change power and radiation at sunset.

Koz

kozikowski wrote: "Delicate" and "Sensitive" do not get along well if you have a radio station in your neighborhood. Walk around outside. Any tall red and white towers with red lights on top? Your cordless phone with its fractional watt radio transmitter is no competition to a commercial radio station with multiple thousands of watts radiating from one or more efficient antennas. These people can generate problems for over a mile, so you may need to drive around.

Another possibility is you're generating the junk yourself. Do you like to record internet radio stations? Did you leave one running at low volume by accident?

Nope. The only radio I listen to is the satellite radio in my car.

Record a bunch of it without saying anything and then boost the volume with the Amplify tool. See if you can identify it. Borrow a pocket radio and see if you can find the same show.

It comes through pretty loud, enough that even without Amplify I can tell it's 1620 AM, the Catholic radio station. They apparently have a tower a couple of blocks away.

<<<At some times of day>>>

What times exactly? Radio stations change power and radiation at sunset.

Around the evening, usually between 4:30-5.

From what you've said, it sounds like the mike is picking up the Catholic station's show. Is there anything I can do about this? Since the USB mike doesn't seem to have the same problem (why is that?) I was thinking about getting a USB headset style, which might not have the echoing and ambient noise problem that the stand USB mike I tried does.

College radio stations don't have towers unless they're Really Big and Important, and then they're FM, not AM which doesn't cause as many problems.

No, instead of a tower, they radiate from the whole building. It's called carrier current and they actually send radio signals down the power lines in the dorms.


In all cases, your voice generates a Really Tiny Signal at the microphone.

The USB microphone amplifies the voice signal immediately right there and makes it into a digital signal right away which doesn't (typically) have interference problems.

The analog or headset microphone tries to send the really tiny delicate voice signal all the way to the computer which has the amplifiers and digital converters. If the cord to the headset is just the right length, it makes a good antenna to pickup the station.

There's no good easy technical way out. At the risk of looking like a total buffoon, you could try wrapping the whole headset cable in aluminum foil and then touch the foil to the metal case of the computer. If the problem changes, you know you're on the right track. It might vanish.

You could call the station. Sometimes they have techies on staff that know how to deal with interference problems.

Koz

There is one even easier one. Unplug the microphone and clean the connector thoroughly with glass cleaner and paper towels.

It should look like one of these.

http://www.kozco.com/tech/audioconnecto ... ctors.html

Dry it off with more towels and plug it back into the computer several times and then turn it a quarter turn.

Did it change?

Koz