Reference Guide

Recording

Input Monitoring

Suppose you are counting "1, 2, 3" into your sound card very quickly. When you say the first "1," this

sound immediately appears in all the places indicated in the illustration above. In other words, the

analog audio signal is pure electrical signal traveling at the speed of light, so it is immediately

present across all analog audio paths inside the sound card.

Next, you say "2." In the time it takes you do that, the ADC has converted the "1" to digital form and

the Wave In driver has fed it to SONAR for processing. SONAR processes the buffer right away and

passes the processed data right back to the Wave Out driver.

Finally, you say "3." By this time the original "1" has been converted back to analog audio by the

DAC, and that analog signal is mixed in with the "3" you have just said. The ultimate result is that

you hear a "1" and "3" mixed together at the line output of card—seemingly sounding like an echo,

but actually just an artifact of the signal flow through the system.

You can eliminate the echo by muting the line-in from playing back (see “To Eliminate the Echo from

Input Monitoring” on page 261); you’ll send only the processed signal to the sound card outputs. This

technique introduces a little extra latency to what you hear coming out of your sound card, but if you

use WDM or ASIO drivers with your sound cards, the latency is negligible.

say “2”

SONAR

say “3”

SONAR