Which device is recommended for measuring the audio signal waveform's voltage during audio system tuning?

The oscilloscope is the recommended device for measuring the audio signal waveform's voltage during audio system tuning because it provides a visual representation of the waveform. This is critical for audio tuning as it not only shows the voltage level of the signal but also allows the technician to observe the shape of the waveform. This information is essential for diagnosing distortion, clipping, or any anomalies in the audio signal that may affect sound quality.

With an oscilloscope, you can analyze characteristics such as the peak voltage, frequency, and waveform shape, which are all vital for optimizing audio performance. This level of detail can't be achieved with a multimeter, which mainly measures voltage, current, and resistance without visualizing the waveform. Similarly, while a signal generator is used for creating certain audio frequencies for testing, it does not measure or display the waveforms of existing signals. A frequency analyzer can provide frequency response information but does not offer the full visual perspective of the waveform necessary for detailed audio tuning.

Therefore, the oscilloscope is the most effective tool for accurately measuring and visualizing audio signals during system tuning.