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High Quality Audio Coding
Published in Jerry D. Gibson, The Communications Handbook, 2018
Auditory masking: Simultaneous masking describes the effect that a low level audio signal (the maskee) can become inaudible when a louder signal (the masker) occurs simultaneously. Temporal masking describes the effect that a low level audio signal can become inaudible before and after a louder signal has been switched on and off. ISDN: Integrated services digital networks offer end-to-end digital connectivity to support a wide range of communication applications. Customers have physical access to one or two 64 kb/s bearer (B) channels and one data (D) channel (the latter supports signaling at 16 kb/s but can also carry user information). Higher rates than 64 or 128 kb/s are achievable using multiple calls with channel aggregation and may be more generally available in the future as multiple-rate services. ITU: International Telecommunication Union, a worldwide standardization organization. ITU-R is its radiocommunication section, formerly called CCIR, and ITU-T is its telecommunication section, formerly called CCITT.
IMP Processes
Published in Brecht De Man, Ryan Stables, Joshua D. Reiss, IntelligentMusic Production, 2019
Brecht De Man, Ryan Stables, Joshua D. Reiss
Further divisions are possible. There are two categories of auditory masking: simultaneous (spectral) masking and non-simultaneous (temporal) masking. Simultaneous masking refers to the case where both signal and masker are presented at the same time and primarily depends on the spectral relationship between the two sounds. Temporal masking may occur when both signal and masker do not overlap in time. In forward temporal masking, the masker occurs before the desired signal whereas in backward masking the masker occurs after the signal. Thinking of a loud bang preceding or following a spoken word, it is clear that forward masking is the stronger effect.
Sound quality considerations
Published in John Watkinson, The Art of Digital Audio, 2013
Figure 13.5(a) shows that the signal-to-noise ratio (SNR) is the ratio in dB between the largest amplitude undistorted signal the DUT can pass and the amplitude of the output with no input whatsoever, which is presumed to be due to noise. The spectrum of the noise is as important as the level. When audio signals are present, auditory masking occurs which reduces the audibility of the noise. Consequently the noise floor is most significant during extremely quiet passages or in pauses. Under these conditions the threshold of hearing is extremely dependent on frequency.
An Overview of Digital Audio Steganography
Published in IETE Technical Review, 2020
Hrishikesh Dutta, Rohan Kumar Das, Sukumar Nandi, S. R. Mahadeva Prasanna
An audio steganography technique has been mentioned in [42], where information is embedded in the cepstral domain of a cover audio signal. This method combines psycho-acoustical masking feature of HAS with the de-correlation property of the speech spectrum. The main features of this process are inaudible embedding, high payload, and exact information recovery. The inserted secret data is resistant against additive noise and bandpass filtering. This method has been improved in [43] for achieving the same task at a faster speed, with a stronger key-based embedding implementation and with less computational effort. This improved technique uses a pair of arbitrary frequencies instead of using auditory masking frequencies unlike the other methods. However, in this method of data hiding in the cepstral domain, payload and robustness are inversely related, that is, both these features cannot be high at the same time.
Listening to Japanese gardens II: expanding the soundscape action design tool
Published in Journal of Urban Design, 2020
Soundscape Actions in the third main category can also reduce the impact of noise through ‘Auditory masking’. Auditory masking is a common phenomenon in Japanese gardens, owing largely to the extensive use of streams, waterfalls, and other ‘Sounds of water’ that cover noise from the outside world, and/or shift focus from it. Influences from other senses should also be considered. For instance, auditory masking is closely related to ‘Visual masking’, where the focus is shifted by considering visual cues (the source producing the noise is hidden from view, most typically behind a layer of vegetation). For optimal effect, masking strategies should be combined with measures to reduce noise levels. Such combinations are encouraged in the Soundscape Action design tool through its division in three main categories.