Adobe 22011292 User Manual - Page 58

USING ADOBE AUDITION 54 Editing audio files 3 In the Advanced section, Enter percentages for Left Mix and Right Mix: • When you convert from mono to stereo, the Left Mix and Right Mix options specify the relative amplitude with which the original mono signal is placed into each side of the new stereo signal. For example, you can place the mono source on the left channel only, the right channel only, or any point in between. • When you convert from stereo to mono, the Left Mix and Right Mix options control the amount of signal from the respective channel that will be mixed into the final mono waveform. The most common mixing method uses 50% of both channels. For other channel-conversion techniques, see the following topics: • "Extract audio channels to mono files" on page 134 • "Mix audio data when pasting" on page 43 • "Channel Mixer effect" on page 67 Change the bit depth of a file The bit depth of a file determines the dynamic range of the audio. (See "Understanding bit depth" on page 6.) Adobe Audition supports up to 32-bit resolution. You can raise the bit depth of a file to gain a greater dynamic range, or you can lower the bit depth to reduce the file size. Note: Some common applications and media players require 16-bit or lower audio. 1 In the Waveform Editor, choose Edit > Convert Sample Type. 2 Select a Bit Depth from the menu, or enter a custom bit depth in the text box. 3 In the Advanced section, set the following options: Dithering Enables or disables dithering when converting to lower bit depths. If dithering is disabled, bit depth is abruptly truncated, producing a crackly effect on low-volume passages caused by quantization distortion. Although dithering introduces a small amount of noise, the result is far preferable to the increased distortion that you would otherwise hear at low signal levels. Dithering also lets you hear sounds that would be masked by the noise and distortion limits of audio at lower bit depths. Dither Type Controls how dithering noise is distributed relative to the original amplitude value. Usually, Triangular provides the best tradeoff among signal-to-noise ratio, distortion, and noise modulation. Dither type Triangular Gaussian Reduces signal-to-noise ratio 4.8 dB 6.0 dB Noise modulation No Negligible Note: Triangular (Shaped) and Gaussian (Shaped) move slightly more noise to higher frequencies. For additional control, set Noise Shaping options. Noise Shaping Determines which frequencies contain dithering noise. By introducing noise shaping, you may be able to use lower dither depths without introducing audible artifacts. The best shaping depends on the source audio, final sample rate, and bit depth. Note: Noise Shaping is disabled for sample rates below 32Khz because all noise would remain in audible frequencies. • High Pass With a crossover set to 7.3 kHz, drops dithering noise to -180dB at 0 Hz and -162dB at100 Hz. • Light Slope With a crossover set to 11 kHz, drops noise to -3dB at 0 Hz and -10dB at 5 kHz. Last updated 2/16/2012