Final answer:
To check for direct modification of loudness, you should first check the intensity level and frequency of the sound. Loudness is measured in terms of decibels (dB), and frequency is measured in hertz (Hz). You can refer to a graph or table to determine the loudness in phons of a sound with specific intensity level and frequency.
Step-by-step explanation:
To check for the direct modification of loudness, you should first check the intensity level and frequency of the sound. Loudness is measured in terms of decibels (dB), which indicates the intensity level of the sound. Frequency, measured in hertz (Hz), refers to the pitch of the sound. In order to determine the loudness in phons of a sound with a specific intensity level and frequency, you can refer to a graph or table that shows the relationship between these variables.