Digital noise can be shaped to hide where hearing is least sensitive

Evidence

As discussed in Chapter 2, our threshold of hearing is not constant with frequency, as shown in Figure 2.14. We are much more sensitive to sounds around 4 kHz than at the extremes of the frequency range. Therefore a uni­ form quantization spectrum may be more inaudible at low and high fre­ quencies and yet still be heard if it is above the threshold of hearing in the most sensitive part of our hearing range. Ideally we need to have more noise where we are less sensitive to it and less noise where we are more sensitive. This is possible via a technique known as “noise shaping.” — David Howard, Jamie Angus, coustics and Psychoacoustics, 2664

Categorization

• DEFINE: Defines noise shaping as redistributing quantization noise to match the frequency-dependent threshold of hearing.

Related

• Noise shaping exploits hearing sensitivity to boost effective CD signal quality (similarity 0.87)
• Added masking noise prevents off-frequency cues in hearing experiments (similarity 0.86)
• Psychoacoustic noise shaping achieves an effective 120 dB SNR on CD audio (similarity 0.83)
• Uniform masking noise can substitute for threshold-in-quiet across all frequencies. (similarity 0.83)
• Frequency-domain coding using masking avoids transmitting masked sound information (similarity 0.83)
• Auditory threshold for broadband noise is set by the most sensitive frequency region only (similarity 0.82)
• Uniform quantization noise requires about 60 dB signal-to-noise to stay masked (similarity 0.82)
• Masking measurements require noise slopes steeper than the ear’s own selectivity (similarity 0.82)
• Noise-induced high-frequency threshold shifts can make previously inaudible difference tones audible (similarity 0.82)
• High ambient noise forces listeners to raise volume toward hearing-loss levels (similarity 0.82)
• Noise intensity discrimination improves by pooling multiple frequency regions (similarity 0.81)
• Shaping quantization noise to sit 13 dB below the signal renders it inaudible (similarity 0.81)
• Non-uniform quantizer spacing exploits masking and signal statistics to cut noise (similarity 0.81)
• Masking noise raises the loudness threshold and fades audible tones (similarity 0.81)
• A narrow noise band can mask signals multiple octaves away at high stimulus levels. (similarity 0.81)