Digital Audio & Core Concepts: Sampling, Bit Depth, Impedance, and Waveforms

What are the two processes involved in converting analog audio to digital audio?

Sampling and quantization.

What does Sample Rate determine in digital audio?

The frequency resolution (how accurately frequency is captured).

What does Bit Depth determine in digital audio?

The amplitude resolution (how precisely loudness is captured).

What is the definition of Sample Rate?

The number of audio samples captured per second, measured in hertz (Hz).

According to the Nyquist Theorem, what is the maximum recordable frequency?

Half the sample rate.

What is the standard sample rate for CD quality audio?

44.1 kHz.

What is the standard sample rate for film and TV?

48 kHz.

What is the definition of Bit Depth?

The number of volume levels available in digital audio.

What is the standard bit depth for professional recording?

24-bit.

Does higher bit depth lower or raise the noise floor?

It lowers the noise floor, allowing quieter sounds to be captured.

What kind of recording requires greater processing power and more storage?

High-resolution (higher sample rates and bit depths).

What is quantization?

The process of assigning a discrete value (or rounding off) to the measured sample.

What is the benefit of 32-bit floating point recording?

It provides a greater dynamic range and flexibility, acting like a 'movable ceiling.'

What is the weakest audio signal level?

Mic level.

What is the strongest audio signal level?

Speaker level.

What do Mic Level signals require to be brought up to Line Level?

Preamplification.

What device is typically used to convert an Instrument Level signal to a Line Level signal?

A DI box (Direct Box).

What is the standard signal level used for most audio equipment?

Line level.

What is the professional nominal voltage range for Line Level signals?

+4 dBu.

What is Impedance (Z)?

The resistance encountered by audio signals as they travel through gear.

What unit is Impedance measured in?

Ohms (Ω).

What is the function of microphone preamplifiers regarding impedance?

Impedance matching.

What is one result of an impedance mismatch?

Noise, signal distortion, or signal loss.

What is the definition of Phase?

The position of a sound wave in time.

When waves align and add together, what type of interference occurs?

Constructive interference.

What is the resulting effect of constructive interference on amplitude?

A larger amplitude (Higher amplitude).

When waves are out of phase and result in cancellation or a weak signal, what type of interference occurs?

Destructive interference.

What is Comb Filtering?

The result of combining two signals with identical frequency content but different phases.

Which waveform is smooth, continuous, and has no harmonics?

Sine Wave.

Which waveform has a bright and buzzy sound, containing both odd and even harmonics?

Sawtooth Wave.

Which waveform alternates between two discrete voltage levels and contains only odd harmonics?

Square Wave.

Which waveform has a linear rise and fall, containing odd harmonics and a mellower sound?

Triangle Wave.

What is the Fundamental Frequency?

The pitch of the note.

What do Harmonics provide to the sound?

The timbre and color of the note.

Which type of harmonics reinforce and add warmth and smoothness?

Even harmonics.

Which type of harmonics add fullness and aggression?

Odd harmonics.

What does Harmonic Distortion add to a sound?

Texture and character.

How do human ears perceive sound (linearly or non-linearly)?

In a non-linear manner.

What mathematical function determines the values on a logarithmic scale?

Multiplication (or an exponential factor/power of 10).

If you double the distance from a sound source, how does the loudness change in dB?

It results in a -6 dB change (or is half the distance, resulting in +6 dB).

If you have two identical sound sources and double them, how much does the perceived loudness increase?

About 3 dB.

If you double an identical sound, how much does the RMS energy increase?

6 dB.

What dB change is the approximate doubling or halving of perceived loudness?

10 dB.

If a sound is -10 dB compared to another, how much quieter is it perceived?

Roughly half as loud.

Doubling a non-identical sound results in how much of an RMS energy increase?

2.3 dB.

Which sample rate is the CD quality standard?

44.1 kHz.

Which sample rate is the standard for video and TV?

48 kHz.

Name one high-resolution sample rate that is above 48 kHz.

88.2 kHz or 96 kHz.

Which sample rate is considered the audiophile standard?

192 kHz.

Why are higher sample rates often preferred for professional or archival use?

They offer extra headroom and detail.