2. Analog vs. Digital Signal

2.1. Analog Signal

Sound in its natural state is a continuous wave that propagates through the air and is captured by a microphone. This signal is analog, meaning it has no interruptions or discrete values; instead, it is a continuous representation of air pressure over time.

Analog recordings store this information in physical media such as:

• Magnetic tape (reel-to-reel, cassettes)
• Vinyl records (through physical grooves in the material)

🔹 Advantages of analog recording:

✅ Smooth and natural frequency response
✅ No quantization artifacts or aliasing
✅ Characteristic harmonic saturation from tape equipment

🔹 Disadvantages:

❌ Susceptible to background noise and degradation over time
❌ Limited editing and storage capabilities
❌ Dependence on expensive hardware and constant maintenance

2.2. Digital Signal

To overcome the limitations of the analog format, audio is converted into a digital signal through a process called sampling. This means capturing fragments of the analog signal at regular intervals and converting them into numerical values stored as bits.

Digital recordings can be stored in various formats, such as WAV, AIFF, FLAC, and MP3, and are used in a wide range of applications, from recording studios to live streaming and film production.

🔹 Advantages of digital recording:

✅ Higher fidelity and dynamic range
✅ No degradation over time
✅ Easy editing and advanced processing
✅ Efficient storage and distribution

🔹 Disadvantages:

❌ Can introduce artifacts like aliasing if anti-aliasing filters are not properly handled
❌ Loss of information in compressed formats (MP3, AAC)

3. Sampling (Sampling Rate)

Sampling is the process by which an analog signal is converted into digital. In simple terms, “snapshots” of the sound wave are taken at regular intervals and stored as digital data.

🔹 Sampling Rate:

Measured in hertz (Hz), it indicates how many times per second a sample of the analog signal is taken.

The most common sampling rates in audio production are:

According to Nyquist’s theorem, the sampling rate must be at least twice the highest frequency you want to capture. For example, human hearing ranges up to 20 kHz, so the standard 44.1 kHz sampling rate allows capturing frequencies up to 22.05 kHz, preventing aliasing with a proper filter.

🔹 Aliasing and Anti-Aliasing Filters

If the sampling rate is too low, errors called aliasing can occur, where high frequencies that are not sampled correctly appear as lower frequencies, causing distortion. To prevent this, anti-aliasing filters are applied before analog-to-digital conversion.

📌 Practical Example:

If we record an instrument with harmonics above 20 kHz at a 44.1 kHz sampling rate, those harmonics might not be captured correctly. However, increasing the sampling rate to 96 kHz preserves more information from the sound spectrum.

4. Bit Depth

Bit depth determines the resolution of each sample taken during the sampling process. While sampling rate affects temporal fidelity (how detailed the waveform is over time), bit depth affects dynamic range and signal precision.

🔹 Bit Depth and Dynamic Range:
Each additional bit in a digital recording adds approximately 6 dB of dynamic range.

🔹 Effects of Low Bit Depth
If a recording is made at a low bit depth (e.g., 8 bits), quantization noise occurs, a type of distortion where amplitude values are rounded to the nearest level, generating audible noise.

🔹 Dither and Its Importance
Dither is a process that introduces low-level noise to smooth out transitions between quantization levels when reducing bit depth. This is especially useful when converting 24-bit audio to 16-bit, preventing truncation artifacts.

📌 Practical Example:

If we record a vocals track at 24 bits, we have enough dynamic range to capture both whispers and screams without losing quality. However, if we reduce the recording to 16 bits without applying dither, artifacts may appear in the quieter parts.

5. Conclusion

Understanding the fundamentals of digital recording is essential for any audio professional.

✅ Analog signals are continuous and natural, while digital signals allow for precision and advanced editing.
✅ Sampling rate determines the amount of temporal information captured and must be adequate to avoid aliasing.
✅ Bit depth affects the dynamic range and resolution of the recording.
✅ Proper use of dither is crucial when reducing bit depth.

Technological advancements have allowed digital recordings to reach impressive levels of quality, but understanding these concepts is essential for making informed decisions at every stage of audio production.