Simple psiman

He slipped on the jacket and scanned around the corner of the hall outside before he got to the door.
I psi, whispered the pin in his lapel.
Egan Rains let go of the knob and felt for the emblem. It was inconspicuous, smaller than his thumbnail, the disc of the moon against a dark blue background. The markings delineated a face on the moon, and two radiating antennae.
Rains frowned and rolled it in his fingers. He thought he'd stripped himself of unnecessary identification. No harm done since no one in India had seen it on him, or heard it—yet. He looked at the emblem regretfully, turned it over. The back was inscribed: American Association of Psi Astronomers. It had sentimental value but he'd have to get rid of it.
He went to the disposer slot and dropped it into the wall. The insignia came whizzing back and struck the opposite wall. Muttering that foreign devices never worked the way they should, he dug it out. He examined it cursorily and noticed a tiny nick in the surface. That was all. The material was harder than the tough blades of the disposer. His respect for the techniques which made the pin mounted.
Someone walked by in the hall. Had the noise it made when it struck been heard? He let his mind reach out delicately.
I pthi, grumbled the pin.
Now it was lisping—and it was louder. The blow must have damaged the speech crystals inside. Hurriedly he shut off his thoughts and the insignia responded with silence.
Primarily, it was a recognition device enabling people of the same talent, psimen, to identify each other. It served a purpose in America where there were so few, but in India, where mentalist activity was far greater, it was a handicap. It would be gabbling all the time.
Rains crumpled a sheet of paper around the little mechanism and tossed it gently into the chute. The disposer ground noisily and, as he half expected, the pin came hurtling back. He pried it out of the wall again. This time it was slightly bent.