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I want to play the input to my macbook pro's microphone through headphones/speakers after certain delay(5 seconds). I have been doing this on ubuntu for years, using a variation to the answers of this question - how to hear mic sound over speakers- Ubuntu karmic

The closest I have come to achieving this is LineIn and Audacity. I tried adjusting the numbers in Audacity > Preferences > Recording > Latency but it doesn't help.

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user34812
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1 Answers1

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As your mac came with garageband, we can use that to implement this.

First of all, open a new garageband project (any template) with a bpm (beats per minute) of 48, create a new track using ⌘+⌥+N and select Real Instrument.

If the right side panel is already open, then go to the Edit tab. If it's not, then double click the new track at the left of the window (You can ignore the Compressor and Noise Gate, they're turned off). Click in one of the empty spaces and select Track Echo, then click the picture to the left of the newly added effect space (looks like a canyon) to open up the settings.
Set it up like this:

Echo time = 1/2 (NOT "1/2 ." or "1/2t")
Echo repeat = minimum
Echo color: 0 (center)
Echo volume = 100% (maximum)
Original volume = 0% (minimum)

Now, because the echo plugin only supports timescales of up to 1/2t (not enough), we'll need to repeat this effect, as the current setup will delay after 2.5 seconds rather than 5. The easiest way to do this is to click the preset selector (where it says Manual) and click make preset. Save it as whatever you want. Now, add another Track Echo effect underneath the first one, open its settings by clicking its picture, and select your newly made preset.

Finally, make sure your track is blue (selected) by clicking it and press i. This will start monitoring your microphone and repeating what you say 5 seconds later. To stop it, press i again. You can now save the project and open it every time you need this functionality.

Here's the maths (and some badly explained music theory) of how the timing works so you can set it up in different times if you want to.

We needed to set the project up in beats per minute. 5 seconds pass every 12th of a minute, so ideally we would just set 12 as our bpm. However, Garageband has a minimum bpm of 40, so we choose 48 because it is a multiple of 12. Each beat lasts 60 / 48 = 1.25 seconds. We set the project up in the 4/4 time, which means that a beat is a quarter note and there are 4 beats in a bar. We don't care about bars so ignore that. Each beat is a quarter note means that a beat is referred to in our project by 1/4. The echo plugin has a maximum full note length of 1/2 (1/2 = 2/4 so it's two beats) which is equal to 1.25 * 2 = 2.5 seconds. Because of this, we have two echo plugins, both set to 2.5 seconds delay. The second plugin catches the output from the first and delays it again, meaning that the total delay is of course 2.5 * 2 = 5 seconds.

phew.
Sorry it was a bit later than anticipated, my mac decided to run out of battery last night.

Jonah
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