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The psychoacoustic model provides for high quality lossy signal compression by describing which parts of a given digital audio signal can be removed (or aggressively compressed) safely—that is, without significant losses in the (consciously) perceived quality of the sound.
The precedence effect or law of the first wavefront is a binaural psychoacoustical effect concerning sound reflection and the perception of echoes.When two versions of the same sound presented are separated by a sufficiently short time delay (below the listener's echo threshold), listeners perceive a single auditory event; its perceived spatial location is dominated by the location of the ...
These filter outputs are similar to the waveforms that would be observed at places on the basilar membrane tuned to 364, 1498 and 4803 Hz. For each centre frequency, the signal can be considered as a slowly-varying envelope (E BM) imposed on a more rapid temporal fine structure (TFS BM). The envelope for each band signal is shown by the thick line.
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.
There are many different mechanisms of masking, one being suppression. This is when there is a reduction of a response to a signal due to the presence of another. This happens because the original neural activity caused by the first signal is reduced by the neural activity of the other sound. [7] Combination tones are products of a signal and a ...
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 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.
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.