Hiss with Sony ECM-ZS90

[Sunbody]

I am trying to record small meetings of about 6 people in a quiet room. I am using a Sony MD MZ-R50 with a Sony ECM-ZS90 microphone. I am getting a relatively high-pitched hiss in the background. What can I do to eliminate this?

[Christopher]

Welcome to the forums!

First off, try the standard rule of troubleshooting:

Try something else. Do you have another mic you could test? Even a PC one would suffice.

[Sunbody]

Yes. I have tried a levalier mic from Radio Shack and a little stereo mic that came with a cheap Sony tape recorder. There is hiss with all of them. I get the least noise with the levalier mic and the recorder set to "low sensitivity". But it's still there.

I have noticed that if I switch to "hi sensitivity" there will be noise as soon as I plug the mic in, before it's turned on. This happens with all the mics.

[glauber]

I have the same problem. You may need a microphone that can generate higher levels of output.

[Reactive]

Another trick you can do is to record the room noise and microphone noise while on the high gain setting. Generally 10 seconds is plenty. Just make sure there are NO other noises that you are recording.

Now go ahead and record your interview. If you transfer the interview to the computer you can easily filter out the room/mic noise from the conversation.

I recently cleaned up a really hissy bird recording for a freind, she needed to present the bird call as part of her study group. She found that when playing the bird call back over the room's PA system the hiss was very loud and it took away from the original recording of a Hutton's Variable (local Northwest bird).

This is how I cleaned up the recording:

First make a backup of the original.

Use a editing program such as soundforge or cool edit.

Zoom way in and Highlight a section of the recording that has only the background noise.

Open the "remove hiss or noise" plug in that comes with either program.

Select "get noise floor from selection" and apply the filter to the whole recording. Note you should be able to preview a section before doing this.

Go have a cup of tea while the computer edits your wav file.

You should be able to clearly hear a huge difference between the original file and your newly edited and much quieter sound file. You may have to play around with some of the noise removal settings to minimize the flanging sound that can creep in if you try to remove too much background noise. You can also boost the overall levels at this time if you require more of output sound level.

Of interest, the above technique is commonly used by professionals, although in a slightly different manner. The room noise is recorded on a seperate track to allow the editing person to add or remove the voices as needed. Without the background noise you would be able to clearly hear the new voice track being inserted. A old trick but a good one.