Any "audio" experts here?

I need to post process some voice over narration so it sounds like it’s coming from a VHF radio (like a police broadcast). I’m not an audio expert by any means, and have limited resources. I’ve got Audacity and asked over at their forum, but no answers. Anyone here have any ideas, and hopefully links for a tutorial or applications that will help me do this? The narration file will probably be a MP3 or WAV file, but I can probably convert it to anything I need.


I don’t know if I can help much, but what OS are you running?

Windows XP Pro and Ubuntu 5.10…

Ecamegapedal (Linux) is a good effects processor with lots of presets. It’s also a really fast way to convert one sound file format to another.

Uh. Audacity is a great problem, but what the poster needs is a way to learn how to use it, not more programs to install.

Anyways, you can do the effect in Audacity (or any program) with an equalizer. Basically what you want to do is knock out everything except a narrow band between umm… I’d say about 750-2500 hertz. There’s a couple different kinds of EQs out there, but the biggest difference between them will be their interfaces. A graphic EQ with a lot of vertical sliders (like the one in Winamp) is fine.

If you still can’t figure out how to do this in audacity, let me know.

I have a simple idea that should work (in theory).

  1. Play the file on small speakers.
  2. Record the file while its being played from the speakers.

This should give the effect of a police radio on the sound. You might wanna add static or something from free sound effects libraries on the net. Im not an audio expert and havent tried this, so tell me what happens.

Hope this helped = )

Knellotron’s advice should get you where you want to be. Taking out the extreme highs and lows will make the sound more like what you’d hear from a small speaker.

You may also want to add a noise gate in there to simulate the AGC that you find in a lot of microphones. A noise gate cuts out sound when it falls below a certain threshold. I hear it in phones (when on conference calls) all the time. You won’t want to be too aggressive with it or you’ll lose everything, but if you adjust it properly you’ll get a slight clipping effect that should sound like the automatic gain jumping in and out.

(I don’t have Audacity installed on this machine, so I can’t remember if they call it ‘noise gate’ or what. sorry.)

(Edit) Whoops… I need to learn to read.

If the VHF sound you’re referring to is like in the beginning of Pink Floyd’s Wish You Were Here, the “small speaker” technique above will work. The same effect can be achieved by a compressor + a high pass filter (possibly resonant). It’s much easier to control volume and noise levels than the former. It is a very common effect. Almost all effects processors have that in their default libraries. That’s why I recommended an effects processor. Ecamegapedal is cool because it has one line where you can choose an input file, and another where you can choose the output (different formats even). There is a set of preset effects that can be chosen inbetween. So, you just select the input, select a compressor, select the output, it’s done. May not be for everyone, but I like it.

Update: I found a (free) VST plugin called “Space Man” that does exactly what I want. Problem was, that although there’s a plugin for Audacity that allows it to use -most- VST plugins, it didn’t work with this Space Man plugin.

I did some more homework and found that the audio editor that came with Ulead Media Studio Pro (which I bought 2 years ago for $99) does support VST plugins. I gave it a test and it worked perfectly.

Before finding this plugin, I found another thread on the Audacity forum that described how to “tweak” the settings in Audacity to get the effect. I gave it a try and it sounded like it was headed in the right direction, but since I lack experience / knowledge in this area, it would probably take a couple hours of experimenting to get it to the effect I was looking for. So it’s possible with Audacity, I just found a faster way for a noob like me.

Thanks for your help and advice, I learned alot during this little “research” project :wink:

How come we don’t see you at #blenderchat anymore?