**The distortion caused by the use of pulse-amplitude modulation (PAM) to transmit an analog information-bearing signal is referred to as the PAM distortion.**

Pulse-amplitude modulation is a modulation technique that involves varying the amplitude of a series of uniform amplitude pulses according to the amplitude of the analog signal being transmitted. This allows the analog signal to be converted into a digital signal that can be easily transmitted and processed.

However, the use of PAM can introduce several types of distortions to the transmitted signal. These distortions can affect the fidelity and accuracy of the received analog signal. Let's discuss these distortions in detail:

**1. Amplitude Distortion:**
Amplitude distortion refers to the alteration of the original amplitude of the analog signal during the PAM modulation process. This distortion can occur due to various factors such as bandwidth limitations, nonlinearities in the transmitter and receiver circuits, and noise interference. As a result, the received signal may deviate from its original amplitude, leading to a loss of information and fidelity.

**2. Inter-symbol Interference (ISI):**
ISI occurs when the pulses representing different symbols in the PAM signal overlap in time and interfere with each other. This interference can cause errors in the demodulation process, leading to the misinterpretation of the transmitted symbols. ISI is particularly problematic in situations where the channel has limited bandwidth or when the transmitted signal experiences dispersion due to multipath propagation.

**3. Pulse Distortion:**
Pulse distortion refers to the alteration of the shape and duration of the pulses in the PAM signal. This distortion can occur due to various factors such as channel dispersion, noise, and nonlinearities in the transmission medium. Pulse distortion can lead to errors in symbol detection and timing recovery, affecting the overall performance and reliability of the system.

**4. Noise Distortion:**
Noise interference can corrupt the PAM signal and introduce additional distortions. The presence of noise can cause random fluctuations in the received signal, leading to errors in symbol detection and decoding. Additionally, noise can also increase the overall signal-to-noise ratio (SNR) of the system, reducing the quality and accuracy of the received analog signal.

In conclusion, the distortion caused by the use of PAM to transmit an analog information-bearing signal can include amplitude distortion, inter-symbol interference, pulse distortion, and noise distortion. These distortions can significantly impact the fidelity, accuracy, and reliability of the received signal. Therefore, it is essential to carefully design and optimize the PAM modulation and demodulation systems to minimize these distortions and improve the overall performance of the communication system.