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Digital audio principles
Published in Francis Rumsey, Desktop Audio Technology, 2003
Figure 2.21 shows the binary number range covered by digital audio signals at different resolutions using the usual twos complement hexadecimal representation. It will be seen that the maximum positive sample value of a 16-bit signal is &7FFF, whilst the maximum negative value is &8000. The sample value changes from all zeros (&0000) to all ones (&FFFF) as it crosses the zero point. The maximum digital signal level is normally termed 0 dBFS (FS = full scale). Signals rising above this level are normally hard-clipped, resulting in severe distortion, as shown in Figure 2.22.
Mixing Consoles. So Many Knobs, So Little Time
Published in Timothy A. Dittmar, Audio Engineering 101, 2013
Peak meters typically have green, yellow, and red LED light indicators. With digital audio, a meter is needed to quickly respond to transients to ensure that no levels exceed zero and square off the sound wave. A peak meter responds quickly and is essential with digital audio because recording levels in the digital world cannot exceed 0 dBFS. Unlike a VU meter that measures the average amount of voltage, a peak meter measures the peaks.
Mixing
Published in Mike Collins, Pro Tools 9, 2012
When you are working with digital systems, the nominal operating level for any connected analogue audio equipment is sometimes set at 18 dB below the 0 dB Full Scale (0 dBFS) level that represents the maximum allowable signal level in the digital system. This provides headroom of 18 dB higher than the 0 VU level on the analogue equipment. Another standard that is recommended when you are mixing audio is to set the nominal operating level at −20 dBFS. This allows 20 dB of headroom for peak levels, encouraging the mix engineer to create mixes with greater crest factors (peak-to-average ratios).
Dispenser-printed sound-emitting fabrics for applications in the creative fashion and smart architecture industry
Published in The Journal of The Textile Institute, 2019
Yi Li, Russel Torah, Yang Wei, Neil Grabham, John Tudor
The audio source emits all frequencies in the audible range from 20 Hz to 20 kHz in the sine sweep mode over a 20 s time span. The audio source output level is −3 dBFS. The unit of dBFS is equivalent to the decibel level relative to the full scale sine wave showing the maximum peak value. Sine sweeps are used as reference tones to observe the frequency response or identify the adverse effects of room modes; for example, the room background noise is typically in the range of 20 to 200 Hz. The sine sweep produces frequencies with a much higher energy compared to pink noise or white noise. A sine sweep produces only one frequency at a time unlike pink or white noise which produces many frequencies simultaneously. The advantage of the sine sweeps is that it ignores the ambient noise in the room offering better immunity for measuring the frequency response at each fixed frequency value.
Enhancing the quality of service of mobile video technology by increasing multimodal synergy
Published in Behaviour & Information Technology, 2018
F. van der Sluis, E. L. van den Broek, A. van Drunen, J. G. Beerends
The SNR was computed as follows: where the Root Mean Square (RMS) amplitudes of the signal and noise were, respectively, −15 and −6 dB and defined by where X is either the power of the noise or signal and Xr is the power of the reference point of the used dB scale. For all dB values, dB relative to full scale (dBFS) was used as unit of measurement for amplitude levels, with as reference point the digital system's maximum output level. As noise source, white noise was used: a random signal, which adds an equal amount of energy across all frequencies. The RMS for both the noise and signal were calculated and normalised using Syntrillium Software Corporation's Cool Edit Pro 2.1. Normalisation was realised by taking the signal's peak amplitude and amplify the entire signal with a scalar such that its RMS reaches the predetermined level, which is possible without clipping. Consequently, for all audio signals that have the same loudness level was secured.