When using Annex D to test speech intelligibility, which is the other test method besides microphone input?

When using Annex D to test speech intelligibility, which is the other test method besides microphone input?

• A. Digital input
• B. Microphone input
• C. Direct input injection
• D. Analog input

Answer: (C)

Annex D describes two ways to assess speech intelligibility of an emergency voice system: using a microphone to feed the system, or injecting a test signal directly into the system’s input. Direct input injection means introducing a calibrated signal straight at the system’s input, bypassing the microphone and the acoustic environment. This isolates the system’s processing and output path, giving repeatable, comparable results regardless of microphone placement or room conditions. That focus on the electronic path is why it’s the other method specified in Annex D.

Annex D describes two ways to assess speech intelligibility of an emergency voice system: using a microphone to feed the system, or injecting a test signal directly into the system’s input. Direct input injection means introducing a calibrated signal straight at the system’s input, bypassing the microphone and the acoustic environment. This isolates the system’s processing and output path, giving repeatable, comparable results regardless of microphone placement or room conditions. That focus on the electronic path is why it’s the other method specified in Annex D.