Because Pro Tools LE uses the host processor in your computer for audio processing, playback, and recording there is a small amount of audio delay, or latency, when monitoring audio through the system. The degree of latency is controlled by the Hardware Buffer Size setting located in the Hardware Setup dialog box.
From the Pro-Tools Menu bar choose Setups > Hardware > H/W Buffer Size and designate the number of samples. The recommended setting for recording audio is 128-256 samples. For playback, the recommended setting is 512-1024 samples.
Pro-Tools LE also includes a feature called Low Latency Monitoring. This feature allows you to record with extremely low latency and is very desirable for time-critcal overdubs.
To activate Low Latency Monitoring, select Operations > Low Latency Monitoring from the Pro-Tools Menu. Tracks use Low Latency Monitoring when they are record-enabled, assigned to an actual audio input (not a bus), and assigned to outputs 1 or 2. When Low Latency Monitoring is enabled, any plug-ins and sends assigned to record-enabled tracks (routed to Outputs 1-2) are automatically bypassed, and must remain bypassed. Also, these tracks will not register on meters for Master Faders.