Question

Mark the answers true or false as follows: A. True B. False An audio signal is digitized by sampling it at regular intervals.

Short answer

A. True

Step-by-step solution

Understand the concept of digitization

In order to determine if the statement is true or false, we need to understand what digitization of an audio signal means. Digitization involves converting analog signals into a digital representation using an analog-to-digital converter (ADC). This process includes taking samples of the audio signal at regular time intervals.

Analyze the sampling process

Sampling is a key part of the digitization process where the continuous audio waveform is measured at regular intervals to create a series of discrete values. These samples are then used to reconstruct the audio signal in a digital format. This method is essential for converting analog signals to digital.

Assess the statement validity

Given that the digitization of an audio signal involves the process of sampling at regular intervals, we can see that the statement 'An audio signal is digitized by sampling it at regular intervals' accurately describes the sampling aspect of digitizing an audio signal.

Key concepts

Analog-to-Digital Conversion

When we talk about changing an audio signal from one form to another, specifically from analog to digital, we refer to this as **analog-to-digital conversion**. An audio signal in its natural state is analog, continuously varying in voltage and frequency over time. To be processed or stored on a computer, it must be converted into digital format.

This conversion is carried out by a device called an Analog-to-Digital Converter (ADC). An ADC's role is to take the infinite possibilities in an analog signal and translate them into a finite set of numbers that a digital system can understand. This is how it works:

• **Sampling:** Captures the amplitude of the signal at discrete points in time.
• **Quantization:** Assigns a numerical value to these amplitudes, rounding them to the nearest level on a digital scale.
• **Encoding:** Translates these numbers into a binary code that a computer or digital device can read.

Through these steps, a continuous audio wave becomes a series of numbers, which form the digital representation that mirrors the original sound. Without ADCs, digitization, as we know it, would not be possible.

Sampling Process

The **sampling process** is a crucial element of converting analog signals into digital form. During sampling, the analog audio signal is measured at regular intervals, creating a map of values that represent the sound. Think of it like drawing dots along a wave, where each dot is a sample.

The rate of sampling is important and is expressed in hertz (Hz), which describes how many samples are taken per second. For example, CD-quality audio typically uses a sampling rate of 44,100 Hz, meaning 44,100 samples are taken each second.

Higher sampling rates capture more detail, allowing for better sound quality and fidelity. However, higher rates also require more storage and processing power.

• **Nyquist Theorem:** States that the sampling rate must be at least twice as high as the highest frequency in the audio signal to accurately capture all information.
• **Aliasing:** If the sampling rate is too low, different signals can become indistinguishable from one another, leading to distortion.

In essence, sampling is the process that translates analog waveforms into discrete signals that can be quantized, encoded, and stored digitally.

Digital Representation

Once an audio signal is sampled, it undergoes quantization to form a **digital representation**. This representation is a critical outcome of the ADC process and is what digital devices read and play back.

Quantization converts each sampled amplitude into a digital number. The precision of this process depends on the number of bits available:

• **Bit Depth:** The number of bits used for each sample. Common bit depths include 16, 24, and 32 bits, where higher bit depths provide more detailed and dynamic representations of the sound.
• **Dynamic Range:** With more bits, the range of volume levels that can be represented increases, leading to sound playback that is rich and less prone to distortions such as background noise.

Once quantized, the digital representation involves encoding these bit values into binary, a series of 1s and 0s. This binary data is then ready for storage on digital devices like computers, smartphones, and more.

Through digital representation, the nuances of sound are captured, stored, and can be manipulated with precision, bringing the full audio experience into the digital domain.