Body is same as ME146, but ear tip is Hearing Components product. Earphone-microphone has both functions for microphone and earphone usable in a noisy environment, with ME148 driver unit of high conversion efficiency employed.

Frequency characteristic as an earphone
Measured with IEC:711 coupler used

Frequency characteristic as a microphone
Measured at 25mm apart from the sound source 0dB =1V/0.5

Though a frequency characteristic as an earphone has a very distinctive curve, to get a sound and voice clearly listenable even in a noisy environment, and also to get a user's voice clearly caught as a microphone, which leaks from an auditory canal, a filter is provided to attenuate the lower frequency via mechanical system of driver unit.

This is a graph showing the outside noise isolation performance of ME150.
With a test person positioned at 50cm away from and in front of a speaker outputting a white noise of 1Pa(94db)=0dB;

A(blue) curve shows an output from the speaker measured through a 1/4" microphone positioned close to the test person's ear.
B(pink) curve shows its microphone characteristics when ME150 is positioned at the entrance of an auditory canal.
C(brown) curve shows its microphone characteristics when ME150 is inserted into an auditory canal.
D(violet) curve shows an output characteristics from ME150 when the test person pronounces "Hello" under the above "C" condition.

Difference between the above "A" and "C" curves represents the outside noise isolation performance of ME150.
Difference between the above "D" and "C" curves represents how ME150 caught a user's voice in a noisy circumstance.

Above graph shows how high ME150 performs the outside noise isolation, and how nicely it can catch a user's voice even in a noisy circumstance outside.