User's Manual - Cornell Lab of Ornithology - Cornell University

Chapter 2: Signal AcquisitionSetting therecording levelThe two horizontal bars labeled Track 1 and Track 2 are recording levelmeters. The Track 2 bar is active only if Track 2 is checked. The meterindicates the strength of the incoming signal, like a recording level meter orLED display on a tape recorder. The numerical scale is in arbitrary units thatare proportional to the logarithm of the signal amplitude. The scale is usefulfor making repeated recordings at the same level. The meter, which is activeas soon as the dialog box appears on the screen, incorporates a “peak bar” thatshows the highest level the meter has registered in the preceding 1.5 seconds(this facilitates adjusting the level for short transient peaks).You’ll get the best recording by adjusting the level so that the strongest part ofthe signal almost fills the meter bar. If a signal’s amplitude is high enough tocompletely fill the meter bar, the recorded signal will be distorted. If the gaincontrols in the dialog box don’t allow you to obtain the desired recordinglevel, or if your Macintosh is not equipped with adjustable gain, you will needto adjust the output level of the device (e.g., tape recorder, MacRecorder) thatyou’re acquiring from. (If you’re acquiring from the Macintosh’s microphone,adjust the loudness of the sound source or the distance between themicrophone and the source.)If you plan to make calibrated amplitude measurements from the signals yourecord, be sure to acquire the calibration signal and all data signals using thesame gain settings. Chapter 4 contains further information about calibratedamplitude measurements.Recording to memoryCanary allows you to record either to active memory (RAM) or to a disk file.This section describes recording to memory; the next section discussesrecording to disk.Canary 1.2 User’s Manual 39