With the progression of audio options like iMessage audio messages and taking phone calls from iOS 8 in OS X, you might find yourself using your Mac’s microphone far more than in the past. However, there may be times when in attempting to chat with people or record audio messages, you find your recordings are either too faint and require the recipient to crank up his or her volume, or are saturated where words you say are overcome by a loud and buzzy sound.

If this happens to you, then you need to adjust the input gain of your microphone to optimize its ability to pick up your voice.

Every recording device has a dynamic range, which is the volume range between the minimum signal it can discern from the innate noise of the device, and the maximum signal it can distinguish from other signals. The best recording will be one that fills out this range as much as possible, but if your voice is too quiet or the microphone is too far away, then you might only fill out a small portion of this range. The resulting recording will be low or sound “distant” in nature, and require boosting.

On the other hand, if your voice is too loud, or the microphone is too close, then you might push the microphone to its maximum too easily, and result in a clipped and buzzy- or warbled-sounding recording.

To adjust the input gain of your Mac’s microphone, in most cases the only adjustment you will have to make is to the system-wide input level in the Sound system preferences:

1. Open the Sound system preferences
2. Go to the “Input” tab and select your microphone
3. Drag the Input volume slider to its maximum level (to the right)
4. Speak as you intend for your recordings.

When speaking, you will see your input volume register on the Input Level meter below the volume slider. Adjust the input gain level until the maximum level is only barely reached. This will be a balance of microphone distance and the input volume setting. For the clearest voice recordings, move the microphone comfortably close to you, and then lower the input volume to compensate if the input volume regularly goes too high. Note that the maximum level might go beyond this in response to harsh sounds like hard “T” sounds in words, so disregard these instances and only concentrate on the average volume level.

If the volume level is always high, then you might have to move the microphone further away from your mouth, or if you are using a third-party microphone then you will need to use a preamp (perhaps built-in on the device) to lower its gain. Again, when doing this, first drag the input volume on your Mac to its maximum, then adjust the input gain on your microphone, and finally (if needed), adjust the settings in the Sound preferences of your Mac.

For volumes that are too low, even if you bring the microphone closer to your mouth or speak louder, then you will need to boost your microphone gain. Unfortunately if this is happening even when your input volume is at its maximum, then you will need another device such as a preamp for external microphones, to boost your input volume. Without this, you will be stuck with the lower input volume.

Sometimes programs that handle audio input and recording will have their own separate settings for managing audio input gain. In these cases, you can adjust the input volume in these programs in addition to the system preferences. To do this, as with prior approaches first set your Mac’s input volume to its maximum, and then adjust the settings in the programs. Then only adjust the input volume in the system preferences if necessary.

Additional troubleshooting and options:

Beyond the input volume adjustments, you might find yourself faced with other odd problems with managing your microphone, including no input, lack of input devices, or the inability to adjust advanced options.

1. If no input device showing, try rebooting your Mac in Safe Mode (hold the Shift key at the boot chimes when you restart), and then reboot normally, to reset and re-load the system’s audio configuration. Next, try uninstalling or at least updating any third-party audio drivers and other audio-handling software.
2. If you have no input volume for devices you select, then ensure they are properly attached to your Mac, and for USB, FireWire, and Thunderbolt devices, check for any audio driver updates (if required).
3. If your audio device has no input volume level settings, then these settings are considered inapplicable. You should then have options for these on your hardware devices (preamps, or otherwise). Alternatively, if you have combined devices in an aggregate device, then you will have to handle the input volumes for each separately in the Audio MIDI Setup utility (used for setting up the aggregate device in the first place).
4. If you would like to adjust advanced audio format settings such as bit depth and sampling rate of your audio input, then you can do so by selecting separate devices (or individual components of aggregate devices) in the Audio MIDI Setup utility, and then changing the options in the Format drop-down menus.