On a Mac, this (delaying a radio signal in order to sink with the MLB, or any other, broadcast) can also be accomplished with GarageBand and delay effects that are included in the software.
Run a male-to-male 3.5 mm cable from the headphone or line out from your radio to the audio input of your Mac (usually located next to the headphone out on Mac). Turn the audio on and set volume to about 1/3.
Open the ‘System Preferences’ application in your dock, and click the ‘sound preferences’ (speaker icon). Select the ‘input’ tab and ‘line in’ as the sound input source. You should see the ‘input level’ meter light up, indicating that the computer is seeing your source audio. Adjust the level with the slider so that the signal is not clipping.
Open GarageBand and create a new project.
In the lower right corner of the GarageBand window, be sure ‘input source’ is set to: ‘built-in input.’ In the setting below this, set ‘monitor’ to ‘on’.
Enable 'record' on the track that appears in the window (click the red button). Adjust the slider below the audio meters so that audio is not clipping.
Adding the delay: Click the ‘edit’ tab to the right of your GarageBand window.
In the effects column, mouse over the bar that says ‘click here to add an effect’ and do that.
Under “AU Audio Effects” select AUDelay.
Mouse over the icon for the effect you’ve just added and you will see three sliding bars, click that.
Change settings to:
dry/wet mix: 100% (to take out the original signal)
delay: maximum (I can’t get it to go past 2 seconds, even though the window suggests that I should be able to)
lowpass cutoff frequency: maximum (22,050 HZ)
Repeat step 5, adding additional delays onto the signal until you get the delay you want. You can adjust the delay length on the final effect plug-in to achieve the desired result. Note: the track allows for 4 delay effects to be added, which gives you a maximum delay of 4 x 2 seconds or possibly more, depending on the version you are using of GarageBand and the AUDelay.
If you need more delay, you can click the ‘Master Track’ tab above the track ‘edit’ tab and, using the same procedure outlined in step 5 above, you add another delay unit to your chain and achieve a full 8-second delay.
If AUDelay does not give you enough of a delay, there a many free plugins that are GarageBand-compatible and have longer delay times. Voxengo is one of many software developers that offer a free sound delay plug-in (in Mac and Windows compatible versions) and their plug-in offers a 3 second delay (http://www.voxengo.com/product/sounddelay/). Installation is drag and drop, just check the website and follow the directions.
Finally, as these effects can add unwanted noise to your signal, use the visual EQ to process to your taste/system.