A Toothache on Zenob

Strange to think that from twenty-odd light-years away, other eyes see our own Sun blazing in the middle of a familiar constellation....
Pehn Karn sat in the signal dome, idly waiting while his friend, adjusted the dials of the receiver. The recording tape spilled over the table in loops of aluminum.
Doesn't this job get dull? he inquired.
Nautunal turned the fifth dial a few degrees, and glanced up. Depends on your interest. It's true this is just routine space-sweep, but noise from space is amazingly variegated. Just one more sector to scan tonight, and I'll be through. What's matter with you, Pehn? Your face looks little lopsided.
Pehn tried to grin, and fingered the slight swelling on his cheek. My face will never be my fortune, I guess. I don't know what's matter. Just ache.
Even at his best, as Pehn's family loved to remind him, he was an ugly young man; he had none of the rounded placidity of feature which was the ideal of his race. His olive skin stretched too tightly over his cheekbones, and his black eyes peered too intensely from their deep sockets. It helped very little that he happened to be extremely intelligent.
Pehn covered the aching place with his hand, and tried to concentrate on the emerging spills of tape. As a matter of fact, he had been having severe periodic toothaches for six months now, but had never spoken of it.
Suddenly he bent forward. Hold it! Just minute. Let me see that.
Nautunal raised one eyebrow. Don't let it get you, lad. Listening to space is apt to make you jumpy. Your friends over at Atomics wouldn't like that. More than once I've thought I was finding some sort of sense in all this chatter, but it never pans out. It's just noise. There may be other inhabited planets besides Zenob, just as Bidagha claims, but if so, they aren't talking.
Stop, watch tape, said Pehn. Nautunal shrugged his shoulders, but he picked up the tape and watched as it trickled through his fingers.
The machine was recording short bursts of energy, separated by distinct pauses: .. .. .... ... ... ...... .... .... ........