Digital Sound
1. Analog vs. Digital
Sound is naturally Analog (a continuous wave). Computers are Digital (discrete binary). To store sound, we must convert the analog wave into digital data using an ADC (Analog-to-Digital Converter).
The amplitude (height) of the sound wave is measured at regular intervals and recorded as a binary value.
2. Key Factors Affecting Sound Quality
A. Sample Rate (Frequency)
The number of samples taken per second, measured in Hertz (Hz).
- High Sample Rate: More samples per second = Smoother, more accurate reproduction of the original wave.
- Standard CD Quality: 44,100 Hz (44.1 kHz).
B. Sample Resolution (Bit Depth)
The number of bits used to store each sample. This determines how many different "levels" of volume (amplitude) can be recorded.
- High Resolution: More bits per sample = Larger range of volumes and less "quantization" noise.
3. Calculating Sound File Size
File Size = Sample Rate (Hz) × Resolution (bits) × Time (seconds)
Example: A 10-second mono clip recorded at 44,100 Hz with 16-bit resolution.
- Calculation: $44,100 \times 16 \times 10 = 7,056,000 \text{ bits}$
- In MiB: $7,056,000 \div 8 \div 1024 \div 1024 \approx 0.84 \text{ MiB}$
4. Impact of Changing Settings
| Action | Impact on Quality | Impact on File Size |
|---|---|---|
| Increase Sample Rate | Higher (Better accuracy) | Increases |
| Increase Sample Resolution | Higher (Better dynamic range) | Increases |
5. Playback: The DAC
To hear the sound, the binary data must be converted back into an analog signal using a DAC (Digital-to-Analog Converter). This signal is then sent to an amplifier and speakers/headphones.