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Psychoacoustics is the branch of psychophysics involving the scientific study of the perception of sound by the human auditory system.It is the branch of science studying the psychological responses associated with sound including noise, speech, and music.
The psychoacoustic model looks at the energy in each of these subbands, as well as in the original signal, and computes masking thresholds using psychoacoustic information. Each of the subband samples are quantized and encoded so as to keep the quantization noise below the dynamically computed masking threshold.
Changes in the signal envelope can be measured using several different procedures. The presence of noise or reverberation will reduce the modulation depth of a signal, and multiband measurement of the envelope modulation depth of the system output is used in the speech transmission index (STI) to estimate intelligibility. [259]
The greatest masking is when the masker and the signal are the same frequency and this decreases as the signal frequency moves further away from the masker frequency. [1] This phenomenon is called on-frequency masking and occurs because the masker and signal are within the same auditory filter (Figure C).
The masked thresholds are calculated through simultaneous masking when the signal is played to the subject at the same time as the masker and not after. To get a true representation of the auditory filters in one subject, many psychoacoustic tuning curves need to be calculated with the signal at different frequencies.
A signal and its envelope marked with red. The timbre of a sound is also greatly affected by the following aspects of its envelope: attack time and characteristics, decay, sustain, release (ADSR envelope) and transients. Thus these are all common controls on professional synthesizers. For instance, if one takes away the attack from the sound of ...
The next image represents a simple block diagram of the relationship between the human audio system and an objective psychoacoustic model. thumbs. From the model comparison of the test signal with the (original) reference signal, a number of model output variables are derived. Each model output variable may measure different psychoacoustic ...
The PSQM algorithm converts the physical-domain signal(s) into the perceptually meaningful psychoacoustic domain through a series of nonlinear processes such as time-frequency mapping, frequency warping and intensity warping. The quality of the coded speech is judged on the differences in the internal representation.