Recording levels

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The level at which you record your audio is very important. If the level is set too low, your audio will have background noise when you turn the volume up to hear it properly. If the level is too high, you will hear distortion. This page explains how to avoid these problems by testing the recording level before recording for real.


Contents


Monitoring the level visually

The process of testing the recording level without actually recording is called monitoring . To do this in Audacity, you need to use the Meter Toolbar:

Metertoolbar.png


If the meters are not visible, click View > Toolbars > Show Meter Toolbar
or in legacy 1.2.x go to the Interface tab of Preferences and check Enable Meter Toolbar.


In the image above, the left-hand VU Meter with the green bars measures the playback level, and the right-hand meter with the red bars measures the recording level. Assuming you are recording a stereo track , the upper bar stating "L" refers to the left-hand channel, and the lower bar "R" refers to the right-hand channel. The values on the meter are negative decibel  values below the distortion level, where the distortion level has a value of zero (0). Hence the smaller the negative values become, and the closer the meter reads to the right-hand edge of the scale, the closer you are to the maximum possible level without distortion.

To start monitoring, look at the right-hand recording meter just to the right of the recording symbol, and click the downward-pointing arrow:

Metertoolbarmonitor.jpg


This reveals a dropdown menu:

Monitormenu.jpg


The menu has several options. "Vertical Stereo" will rotate the meter so that the zero level is at the top, and "Linear" will change the meter scale so that the values read from zero to 1.0 where the distortion level has a value of 1.0. Some users find this scale easier to understand than the logarithmic  decibel scale. For now however, the option we choose to monitor the recording is Start Monitoring (this reads Monitor input in legacy Audacity 1.2.x).

Now you can start singing into your microphone, playing your guitar (or your record or tape), and you will see the red recording bands move in real time with the loudness of the input signal. If you can't hear what you are recording, this doesn't matter for the purposes of the level test because the meters will indicate the level accurately: the next section describes how you can set up so as to hear what you are recording.

For most purposes, an optimal recording level is such that when your input is at its loudest, the maximum peak on the meters is around –6.0 dB (or 0.5 if you have your meters set to linear rather than dB). This will give you a good level of signal compared to the inherent noise in any recording, but without creating distortion. Distortion is often referred to as clipping , because at this point there are not enough bits available to represent the sound digitally, so they are trimmed off above this point.

Enlarging the Meter Toolbar by clicking and dragging may help gauge levels more accurately
.

To adjust the input level itself, use the right-hand slider (by the microphone symbol) on the Mixer Toolbar:

Mixertoolbar input slider.png


Move the slider left or right until the recording level settles at about -6 dB. If the meter bars drift so far to right of -6 dB that they touch 0, the red indicator will appear to right of the meter bar, as in this image where the left hand channel has at some stage peaked beyond the distortion level:

Metertoolrec.png


As soon as you see the red indicator you'll know you have increased the input level too far, so will need to move the input volume slider back leftwards. Note that the achieved recording level is a combination of both the input level you record at and the output level of the source. If you find you achieve near maximum levels on the recording meter with only a very low setting on the input slider, this may lead to the recording sounding excessively close and un-natural. In this case you may want to cut back the output level somewhat if you can. Similarly if you can't get close to maximum levels on the meter even when the input slider is on maximum, try turning up the output level.

If you find the meters don't respond at all to the input slider, double-check that you are recording from the correct input source as selected in the dropdown box to right of the input slider. If you still have problems, try setting the levels in the system mixer instead. On Windows machines this is done through the Control Panel, and on Mac OS X systems this is usually done in Apple Audio-MIDI Setup.

There is no reason you can't use a standalone recording meter if you prefer, such as this Audio Level Meter  for Windows.

Monitoring the audio using playthrough

The simplest way if you wish to hear what the monitored input sounds like is to go to the Audio I/O tab of Audacity Preferences, and enable Software Playthrough. Don't enable this option if you are recording sounds the computer is playing with the sound device's "Stereo Mix" or similar option, because this will lead to echoes or even failure of the recording.

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