To measure the signal level of an analog audio signal, which measurement scale is required on a DMM?

The correct measurement scale required on a Digital Multimeter (DMM) to measure the signal level of an analog audio signal is AC Volts. Analog audio signals are alternating current (AC) signals, meaning that they vary in voltage over time, oscillating above and below a reference point (usually ground). When measuring these signals, it’s crucial to capture the instantaneous voltage levels as they fluctuate.

AC Volts mode on a DMM is specifically designed to measure these types of signals, providing readings that accurately reflect the varying nature of the audio signal being tested. This measurement gives an indication of the signal's effective voltage level, essential for understanding the strength and quality of the audio signal present.

The other choices refer to different contexts. Voltage RMS is a method of calculating the effective value of an AC voltage, which could indirectly be helpful, but the direct measurement for most audio diagnostics is typically set to AC Volts. DC Volts would measure the steady-state voltage, which is not applicable for measuring the dynamic characteristics of audio signals. Frequency Response pertains to how a device or system responds to various frequencies but does not measure voltage levels directly.