"May I borrow your peanuts?"

She turned a pair of emerald eyes at me and smiled as she handed the tinfoil packet. I have struck lasting friendships with co-passengers in trans-Atlantic flights and I had a feeling this chance encounter would prove no exception.

"My name is Sam." - I said - "I am a shrink, but don't hold it against me."

She laughed. Her voice was husky and suffused with timbre and warmth:

" I like shrinks." - she said - "They are always good company and have interesting stories to tell. Is there anything you can share with me? As part payment for the peanuts?"

Actually, there was. I turned off my overhead lamp and sprawled in my seat, eyes shut:

"A few years ago, just out of school, I opened a fledgling practice, a cubicle really, within the offices of a more established colleague, a lifelong friend of my father's. One of my first clients was referred to me by him. She was a woman in her forties, well-dressed, soft-spoken, and incredibly erudite. She suffered from recurrent though intermittent chest pains, chills, overpowering sadness, and paralyzing anxiety and loathing, bordering on outright terror."

"I know how she must have felt." - Remarked my companion quietly.

I stole a curious glance at her, but made no comment:

"It was a strange affair. Her crippling sensations and emotions would come and go in cycles of about a half year each. I didn't know what to make of it. I was not aware of any periodicity in brain biochemistry which matched this amplitude. Her situation has only gotten worse: she began to neglect her appearance and to gradually avoid all social contact. She developed paranoid ideation and persecutory delusions: she refused to eat or drink, claiming that someone was surely poisoning her. She even became violent and attacked her neighbors with a kitchen knife. She said that they were ghosts out to haunt and drive her to insanity or cardiac arrest. We had to commit her and place her under restraint. I was at my wits end and none of the colleagues I have consulted could offer any useful insight."

"Was she married?"

"Yes, but her husband was somewhere in Africa, studying elephants."

She perked up:

"I am an ethologist, I study animal behavior. What is his name?"

"I am not at liberty to tell you, I am afraid." - I shifted in my seat, embarrassed - "Medical secrecy, doctor-client privilege, all that jazz, you know."

"Sorry! How stupid of me! Of course you can't!" - Even in the relative dimness, I could see that she was blushing.

"Don't worry about it, no harm done." - I attempted to calm her - "On the bright side, I can tell you what he was up to. She described his profession as a bioacoustics engineer. He was involved with a global campaign called the Elephant Census Project. He spent months on end taping their calls and trying to correlate them with various demographics: how many males there were, hormonal condition of the females, age, that sort of thing."

"I heard about the project." - She nodded, absent-mindedly.

"Anyhow," - I sighed - "he wasn't of much help. When he did return home, which was rarely, he would set up his tape recording equipment in a shed and play the tapes for days on end. He told my client that he was trying to spot migration patterns of the herds and other behavioral cues, using complex statistical procedures. She lost me there, but it sounded interesting, I must admit."

"More interesting than you know." - Blurted my interlocutor - "Prey, continue."

I glanced at her, surprised

"This means anything to you? Perhaps you are in the same line of work? I shouldn't have gone on in such detail, I am afraid. It is a breach of ethics to provide information that can allow others to identify the client."

She chuckled:

"Don't worry, you haven't." - She said - "I am into an entirely different sub-field."

"Good to hear." - I responded, relieved.

The aircraft shook as it dove into an air pocket. The lights flickered. She suddenly lurched and held onto my hand.

"Apologies." - She muttered when the plane stabilized - "I am afraid of flying."

"We all are," - I soothed her - "only some of us are less frank about it than you."

She smiled feebly and recomposed herself:

"Elephants emit low frequency waves called infrasound. They can't be detected by the human ear, they are not audible."

"So?"

"These waves affect our vision by vibrating our eyeballs. People exposed to these waves become moody, depressive, even suicidal. Many develop a tingling sensation in the spine, chest pains, and a host of other symptoms. They become anxious, phobic, fearful."

I stared at her, dumbfounded.

"Whenever her husband returned from Africa, he would play the tapes, you said."

I nodded, awestruck.

"The infrasonic waves, captured on the tapes, would assault her. This explains the cycles."

"But ... he worked in a shed at least 50 meters away from the main house!"

She laughed mirthlessly:

"Infrasonic waves go on for miles undiminished and undisturbed. They are known to circumvent any and all obstacles. Elephants use them to communicate over vast expanses of land."

I sat there, transfixed, but then shook my head:

"Impossible. If the infrasonic waves affected her, they surely would have affected him."

"Not if he was wearing special gear: earplugs, deflectors. Researchers in the wild use these, too. Some of them have been monitoring elephants and tigers and other infrasound-emitting animals for years without any discernible effects."

I turned to face her, framed against a city shimmering with a thousand electric jewels. The engine hummed. The No Smoking sign turned on. The captain spoke, but I could not remember a word he said.

"He couldn't have been ... Surely, he ... he knew... He must have known?"

She nodded, detached:

"He knew. The effects of infrasound on humans have been recognized almost thirty years ago. Field researchers take special precautions. There is no way he was ignorant of the effects of his work on his wife."

"So ... he ... he murdered her!"

She closed her eyes and took a deep breath:

"She is dead, isn't she?"

"Suicide." - I confirmed - "blasted her head with his hunting rifle. He has just returned from another trip and was playing his tapes in the shed. He claimed to have never heard the shot."