A recent thread about connecting a microphone to an Arduino was closed because there was not enough information.
It showed a photo of a "Sound Sensor Module" that was probably purchased from Amazon.
Since Amazon knows nothing about electronics they show the size and weight instead of the function.
This problem about this module happens frequently.

The module does not produce an amplified audio output, instead its output is a logic high or a logic low and lights an LED when a sound or noise exceeds the level set by the trimpot. Its IC is a comparator, not an amplifier.

 

A recent thread about connecting a microphone to an Arduino was closed because there was not enough information.
It showed a photo of a "Sound Sensor Module" that was probably purchased from Amazon.
Since Amazon knows nothing about electronics they show the size and weight instead of the function.
This problem about this module happens frequently.

The module does not produce an amplified audio output, instead its output is a logic high or a logic low and lights an LED when a sound or noise exceeds the level set by the trimpot. Its IC is a comparator, not an amplifier.

Dirty conglomerates!

 

Regarding the headphones, the higher the “sensitivity” rating in decibels (dB), the better, but listening is believing: if you’re serious about building a detector with maximum sensitivity for small electrical signals, you should try a few different headphone models at a high-quality audio store and “listen” for which ones produce an audible sound for the lowest volume setting on a radio or CD player.

All audio systems have a volume control that sets the amount of sensitivity to sound levels, not the speakers or headphones.
Very poor quality speakers or headphones can sound loudly boomy or shrieking with high distortion at only a few frequencies.
Very high quality speakers or headphones can smoothly produce all sound frequencies at the same level (a flat frequency response) with low distortion but at a lower level than the awful sounding ones. Then have their sensitivity increased by turning up the volume control.

The Sound Sensor circuit was not designed with a pre-amplifier to produce a high level sound output from a microphone. Instead it uses a comparator IC to give a digital high or low output that sound levels are higher than the setting of the "loudness" trimpot as a warning.

 

All audio systems have a volume control that sets the amount of sensitivity to sound levels, not the speakers or headphones.
Very poor quality speakers or headphones can sound loudly boomy or shrieking with high distortion at only a few frequencies.
Very high quality speakers or headphones can smoothly produce all sound frequencies at the same level (a flat frequency response) with low distortion but at a lower level than the awful sounding ones. Then have their sensitivity increased by turning up the volume control.

The Sound Sensor circuit was not designed with a pre-amplifier to produce a high level sound output from a microphone. Instead it uses a comparator IC to give a digital high or low output that sound levels are higher than the setting of the "loudness" trimpot as a warning.

How would you characterize the transducer on a generic product like this?

 

How would you characterize the transducer on a generic product like this?

If she talks into a microphone with speakers nearby then there will probably be acoustical feedback howling. Then the transducers must be headphones. Maybe she records sounds then plays them back later through loudspeakers when the microphone is turned off.