Hello, new to the forums.
I have to ask, is it possible in Audacity to manipulate a voice so it has the sound of a police loudspeaker in a car. Basically I’m working on a scene in some machinima project in which a character is pulled over. A police officer in the scene speaks over a loudspeaker. I’m hoping for an effect exactly like this.
Try a high pass filter at about 300 or 400 Hz and then a low-pass filter at about 4000 or 5000 Hz. That will kill the high & low frequencies and give you “telephone quality”. You can experiment with the cutoff frequencies to find a sound you like.
Then try the hard limiter. This will add some distortion to give a “harsh” and “constricted” sound. Maybe try somewhere around -9dB. And, you’ll probably have to use the Amplify effect to bring the volume back up after limiting.
Then, you might try a small amount of echo.
You can also try using the Generate command to generate some white noise or pink noise, and then mix that in with the voice.
Oddly enough, every effect I applied (minus the echo) didn’t seem to have a whole lot of effort on the audio file. Maybe I did something wrong, but I’m not sure. The echo effect didn’t quite work either, I personally think a Reverb effect comes in more useful.
That’s a Hollywood version. An actual megaphone would be less Hi-Fi …
You need a feed-back resonance*-effect : in reality the mic on the megaphone picks up the the sound produced by the megaphone, creating a feedback-loop.
[ * e.g. JS Resonnateur V1.0.dll … Missing features - Audacity Support ]
Oddly enough, every effect I applied (minus the echo) didn’t seem to have a whole lot of effort on the audio file. Maybe I did something wrong, but I’m not sure.
I’m trying to give you a starting point… “More” of any these effects, and you WILL start to hear it… It may not be what you’re looking for, but these things can make a BIG difference in the sound…
A higher high-pass filter will make a bigger effect. A lower low-pass filter will make a bigger effect. (I wouldn’t go too far down with the low-pass, because the more you kill the higher frequencies the more of the “T” and “S” sound you’ll loose, and that affects intelligibility.
If the limiter at -9dB isn’t making a difference, try -20dB or so. (At -20dB, you’ll probably need to Amplify by +20dB afterwords to bring the volume back-up.) Of course, this effect depends on the starting volume… If you have a “quiet” file with peaks of -10dB (unlikely) then a -9dB limiter won’t do anything.
Added noise should be clearly audible… In fact, the default setting will be way too loud and you’ll have to back it down. And to make it realistic, you’ll need to “modulate” the noise so the noise is only present when the person is talking. (You need to make a separate noise track and then mix it with the voice.)
The echo effect didn’t quite work either, I personally think a Reverb effect comes in more useful.
That’s fine. These are only suggestions… You are in charge!!!
I’ll give these a go again, but if all else fails, I’ll go with a telephone plug-in I installed. I appreciate the work either way. 
I meant to say I appreciate the help, but can’t edit my posts for some reason.
And thanks for the link to the plugins Trebor, though the link to the telephone effect seems to be broken. For now, I have a decent enough effect in one of my scenes (used both Audacity and Sony Vegas) though there may be more scenes with loudspeakers.
We don’t generally go back and read old posts, so editing your old messages can lead to a lot of “what-whats.”
“What? That’s not what you said earlier.”
“What? Yes it is.”
The message thread is a one-way stream unless we have to go back and read something.
Koz
The Los Angeles black and whites have a terrific sound system. It’s the Voice Of God coming up behind you.
Koz
the link to the telephone effect seems to be broken.
There’s a telephone effect built-in. Which Audacity are you using? Some of this stuff doesn’t work if you’re not on Audacity 2.1.0.
Koz