The "transmitted" sound is the human voice that sounds as if it were being broadcasted on an old radio. To this day, Hollywood still uses this trick in movies for phone conversations and anything else where the voice is supposed to sound "old", "old tech" or "distant" (like in war movies).

If you’re into making your own movies/skits/etc., this is a good trick to know during post production editing.

This effect is best heard by example. Here’s an audio excerpt from a recent video I did:

Original (MP3)

Modified (MP3)

This effect can be done in just about any audio editor (including Audacity) and is achieved by doing the following:

1. Increase db by 20 (Amplify).

This will purposely distort the audio and sound – by design – as if it’s being transmitted "too hot". Most broadcasts of old were really hot on the microphone which is why you do this.

Original audio looks like this:

Amplified audio looks like this:

And yes it’s very hot and distorted – on purpose.

2. Compress audio.

The compressor will keep the audio "hot" sounding, but bring the real db back down to a level where it won’t blow out your speakers (or anyone else’s).

Compressed audio looks like this (when run after amplification shown above):

Note how the "hot" audio is maintained but the true volume is leveled down so it doesn’t clip.

3. Convert down to 8kHz 8-bit, then back to 44.1kHz 16-bit.

The original recorded audio was in 44.1kHz 16-bit (CD quality). It was downsampled down to 8kHz 8-bit to chop off all treble for that older raspy sound, then upsampled back to 44.1kHz 16-bit.

In Adobe Audition 1.5 (my audio editor of choice), the downsample is done like this:

After I apply that, the upsample looks like this:

The end result is what you heard above from the examples.

To note, the modified version is supposed to purposely sound distorted and overdriven because that’s what old-tech radio/phone transmissions sound like for the most part.

Final tips:

You may only need to perform step 3 and skip 1 and 2. If it sounds good to your ear, go with it.

Purposely using a distortion filter usually doesn’t work. What you’ll get is the all the "hot" you want but it won’t sound natural.

Chopping off the high bands via EQ usually doesn’t work either. You won’t get that old-tech sound but rather just "mud" (i.e. sounds as if being spoken behind a wall).