On detection of quantization noise in low level reproduction of digital audio system
Masanao Ebata, Kanako Maeda, Kenji Takada, Tsuyoshi Usagawa · Electronics and Communications in Japan (Part III Fundamental Electronic Science) · 1991
Abstract On recent audio equipment, a wide dynamic range of nearly 100 dB is achieved by using 16 bit linear quantization. But quantization noise is still detectable, because relatively few bits are used to represent low‐level signals. When the signal is quantized directly, the quantization noise consists of harmonics of the source frequency. This quantization noise is detectable at 55 dB for a pure tone and at just about 40 dB for complex and modulated tones, if we assume that the maximum reproduction level is 120 dB. This harmonic distortion can usually be reduced by adding dither at quantization. When dither is added, the quantization noise becomes white noise and spreads over the entire frequency range. Experimental results indicate that at frequencies lower than 2 kHz, the detection level of quantization noise is raised by several dB when dither is introduced. But at about 4 kHz, the detection level falls because of the dither; in this case, the white noise induced by the dither seems to function as a detection cue.