Is there a way to listen to the input sound on Mac OS X?

Question

Is there any easy way to listen to the input on a Mac?

For example, assume I have a microphone hooked up to the input (i.e. line in) of my Mac, and I have headphones hooked up to the output of my Mac: is there any way that I can hear what I say in the microphone through the headphones?

This is very easy in Windows XP: simply go to the sound settings for recording devices, check "select" on the line in, and increase the volume – this makes it so you can hear what is said into the microphone.

It has to be in real time; a solution where you record the input and then playback the output later doesn't help.

Solution 1

Take a look at Rogue Amoeba's LineIn. It is a free application which will allow you to do what you want.

Solution 2

With 10.6 (and newer, AFAIK) you can launch QuickTime Player.app and choose File -> New Audio Recording. Then just turn up the volume control that is part of the window that appears. You might hear a bit of white noise when there's no sound and the volume is all the way up but the Rogue Amoeba app does the same thing.

Solution 3

As originally suggested by qu1j0t3, Apple's "AU Lab" provides the ability to listen to the audio input in real-time. (Well, nearly in real-time; for me there is a slight delay from input to output.)

• Download from here: https://www.apple.com/itunes/mastered-for-itunes/ (thanks alex r. g.!)
• Direct link: https://images.apple.com/itunes/mastered-for-itunes/docs/au_lab.zip

(If those links die, it can also be downloaded from Apple Developer Tools, which may require an Apple Developer account.)

• Download from here: https://developer.apple.com/download/more/ > search for "AU Lab"
• Direct link: https://download.developer.apple.com/Developer_Tools/au_lab/au_lab.dmg

Usage:

In the Document Configuration window, select the existing "Stereo In/Stereo Out" configuration. (If the Document Configuration window is not already open, click File → New to open it.) Then click the Create Document button in the bottom right corner.

In the new "Untitled" window that opens, ensure the icon at the bottom says "Audio Engine Running" (or click to toggle if it says "Audio Engine Stopped"). If necessary, adjust the system's overall input and output volume settings in System Preferences → Sound → Input.

Solution 4

You can also use Garage Band. Choose for example the Acoustic Instrument template (the default audio track in it has no effects) and set monitor to on.

Solution 5

If you want to use the terminal, you can install sox (i.e. with Homebrew brew install sox) and then run

sox -d -d

Here, -d means "default audio device", and this command specifies it for both the input and the output, i.e. microphone and speakers/headphones.

You can decrease latency by decreasing the buffer size (default 8192), try what works for you:

sox --buffer 1024 -d -d

View more solutions

Comments

[Mark A. Donohoe]

I know this is (years!) old, but you may want to update the accepted answer to the one about QuickTime Player. Line In has substantial buffering/delay issues (when you restart, it's fine, but after a few minutes, it creeps back in) plus it's a third-party app let alone one that's no longer supported by them. Using QuickTime Player however, it's part of the native OS, there seems to be zero delay, and you get a volume control to boot! Anyway, just throwing that out there Hope it helps!

[deddebme]

LineIn can select line-in/mic/digital-in etc, and there are independent volume control.

[Serg ikS]

delay introduced is significant. I'd love to see a LineIn-like app working with fast ASIO drivers of the available soundcards.

[xizor]

Rogue Ameoba released version 2.3 on 2014.09.03 that has completely eliminated delay.

[chrismarx]

this seems to work just as well as linein, maybe a bit better

[Umair]

Using Intel based Mac.. can't check the 'thru' checkbox.. looks like it is disabled.

[endolith]

This only controls the analog passthrough in a single device/sound card, it will not connect one device to another through software.

[Ryan]

Currently the free version stops working after 10 mins. I was about to try it anyway but had trouble downloading it. Then I found lifehacker.com/5630844/…, which works.

[eloone]

In SoundSource look for "Open Play-Thru Window" and then "Start Play-Thru". I tried, it technically does what I want but the sound is very bad, there is a lot of echo despite tweaking to the settings.. I don't know if it's my mic or my headphones that are bad or sth else.

[eloone]

I tried LineIn it's free and does the job. Still a bit of echo but less then with SoundSource.

[rich]

The free version of SoundSource stops working after 10 minutes, but on their legacy page they still have a download option for LineIn which still works on High Sierra currently.

[Kamil Maciorowski]

Another answer already mentions AU Lab. Your answer is better because it basically follows this outline while the other one does not.

[Chris Tollefson]

@KamilMaciorowski Yes, you are correct - AU Lab was already mentioned in a previous answer, so I have edited mine to mention that. I would have commented/added to the previous answer, but I don't have enough reputation and my suggested edit was rejected, with the reviewer recommending that I add it as a new answer instead. (Sorry, noob problems, not really sure what etiquette I should follow.)

[Mark A. Donohoe]

MAN, I wish I had found this a while ago! This should be the answer, not Line In. This is part of the OS. That's not only third-party, but currently it's legacy, but worse, the biggest issue with 'Line In' is it tends to start to buffer the input, so for instance, using it to route my TV's sound through my computer, it routinely gets out of sync. That doesn't seem to happen with this method. Plus... volume control!! WOOT!

[Mark A. Donohoe]

Well, as of 9/19/2018, Line In still has the delay. It's not at first. It seems to be buffering or something. Restarting it fixes the issue, temporarily. However, as @BrianAshe said in his answer below, use the QuickTime Player! It's built-in, there's never any delay, and best part, you get a volume control for it too!

[Mark A. Donohoe]

Check out the QuickTime Player approach. Even better/simpler and zero lag!

[Mark A. Donohoe]

Have you tried the QuickTime Player trick above? That seems to do the trick great! Not only is there no delay, but you get volume control to boot!

[Merchako]

There's a ~30 millisecond delay when using this method.

[flamewave000]

For those who are having issues with the softpedia website, here is the program's github page. Simply click the "Clone or Download" button and then click the "Download ZIP" button. Extract the ZIP file and you will see the AudioMonitor.app file.

[alex r. g.]

This is a good solution and well explained. The problem is (or at least was for me) that Xcode is currently only available via MacAppStore and one has to use the latest macOS to download it. But luckily Apple still provides AU Lab on this iTunes-Site I found: apple.com/itunes/mastered-for-itunes

[Chris Tollefson]

Thanks @alexr.g. - that link is much easier to get to, so I've updated my answer with it.

[evolutionxbox]

I couldn't find this in the Xcode developer tools, and had to download it from the Apple Developer website.

[Michael]

I'd go so far as to say its a 500ms delay ... Not really workable. Could this be because it's a bluetooth headset with a mic?

[Hans Kristian]

I have the same delay with the built in mic and wired headset.

[compuphys]

Signed up to SuperUser to vote you up! ... I needed this for client calls because my headphone are too good at blocking out residual sounds so I was constantly shouting. When I used them in bluetooth mode there was a considerable delay but using them in wired mode this works perfectly.

[grappler]

Replaced by rogueamoeba.com/audiohijack

[David Silva Smith]

This answer used to be great and I used LineIn. Now the better answer is the one below, using QuickTime Player. That is built-in to the OS simpler to use (I downloaded Rogue Amoeba's software, but didn't quickly figure out how to make it work) and free.

[HaggleLad]

The AudioMonitor.app (downloaded from Github) doesn't appear to be compatible with macOS Catalina. :-(

[Chris Tollefson]

Thanks @compuphys for the +1! Bluetooth introduces additional delay for me too, and I think that's a common experience. For anyone who's curious, Bluegiga (now SI Labs) has published some Bluetooth audio latency figures, ranging from 30 to 150 ms depending on the Bluetooth profile and codec your devices are using.

[Josh]

LineIn no longer functions on newer OS versions, and SoundSource no longer supports playthrough. The only option from Rogue Amoeba is now the $60 AudioHijack.

[Josh]

I also get a delay of hundreds of ms. The meters on-screen move long before I hear the sound through my wired headphones.

[Josh]

This is the only solution here that worked for me, thank you!

[cjohndesign]

Pro tip, unless you've got an external audio device, cover one ear when recording. It makes the delay less noticeable as you're getting the real time sound in your skull then the input after.

[Matthias Fripp]

Both this and the Quicktime answer worked for me, but the Quicktime answer had maybe a 0.5s delay, and this one had no delay, which makes it a lot more natural. My microphone is mono, so I first had to create a new configuration (+ sign at bottom) with mono input and stereo output. Then it worked well.

[Andy Fraley]

This works well on Catalina with a 2019 MBP. I kept getting errors from AU Lab about my input device not having the correct number of channels, you have to create a new User Configuration with the + at the bottom on the new document screen, then you can create a mono input -> stereo output config.

[Marc Tamsky]

Free version using Chrome Web Audio API: stackoverflow.com/questions/37326846/… -- at comment: stackoverflow.com/a/37332145/2411557 -- which mentions this Fiddle: jsfiddle.net/jib1/7ejwaxkc which can source microphone and sink to speaker.

[Alex]

Same here. This is the way to go for me with no lag, nor installing additional software.

[Mason]

👍 Zero perceptible latency using the AU Lab method on M1 Mac Mini with latest Big Sur — if, and only if, I select the "External Headphones" output in AU Lab, which routes the input to the analog 3.5mm headphone jack. (I had bad latency with other outputs.)

[Mason]

Plugging in wired headphones works for my use case, though. My input is a (cheap) Behringer XENYX 302 USB mixer, which is hooked up to a separate (expensive) Mac audio workstation, with various mics and guitars connected to it. The mixer can act as a standard USB audio device, so it can be the "mic" for Zoom, Meet, etc. Latency is very low—low enough for live guitar. This lets one Mac handle audio and effects processing, and serve as the input to the Mac that handles Zoom/Meet. (Presumably, this would work for streaming and live podcasting and stuff like that, also.)

[Grant]

AU Lab works on MacBook Air with M1 CPU using USB mic with much lower delay than the Quicktime method. (although it's compiled for Intel CPU, running under Rosetta)

[Gz Zheng]

make sure to go to Sound preferences and select your input source before you create a new audio recording.

[joecap5]

I get a little bit of a computer modulated voice using this method. Any thoughts for how to correct? Thanks

[Admin]

AU Lab doesn't seem to work on my M1 mac.