Tales from the Qiantang Metrology Institute

Dec 12, 2023
Although the noise was loud, its frequency was lower than that of a subsonic weapon. Inaudible to the human ear, but instruments don't lie, and Jack and Ention could deeply feel it in their bodies. Master Zhang, on the other hand, felt no discomfort. As he said, spending a long time in an environment had already made his body immune.
This story is adapted from real events. Any resemblance is purely coincidental.
Jack and Ention always gave the impression of being meticulous, both in their personal and professional lives.
In their respective fields, Jack excelled in testing and applications, while Ention delved deep into theoretical research and standards. Their collaboration was seamless, consistently sparking creative inspiration.
Qiantang Metrology Institute held a prominent position in the realm of measurements across the vast landscapes of the Middle Kingdom. Master Zhang, head of the Acoustic Metrology department, had studied extensively in Germany, possessing profound knowledge and extensive experience.
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As usual, before each client training session, Jack and Ention personally verified instruments and software, ensuring everything was in order before packaging.
Excitement and nervousness filled the air. This time, they were well aware of the significance of the client; any misstep could tarnish the reputation they had built over the years in the field of acoustic measurements.
With their wealth of experience and confidence, once everything was prepared, they embarked on the journey to Qiantang Metrology Institute.

In the earthly April, the full bloom of spring is revealed. The wind is gentle, the heart is beautiful, and the spirit is also joyful.
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Despite the blossoming of spring, the chill hadn't entirely retreated. People aimed to enjoy the gentle touch of spring, adding as little clothing as possible. The wind in Qiantang seemed even cooler. When the soft breeze brushed past, even Jack, who was usually resistant to cold, couldn't help but shiver.
Waving off the discomfort, he rolled up his sleeves, cradling the equipment, and joined Ention on their way to Master Zhang‘s office.
Busy with an experiment, Master Zhang gestured for them to prepare briefly.
Setting down the equipment, Jack felt a peculiar sensation, as if a powerful force field enveloped the surroundings, generating a surge of oppressive emotions.
Glancing at Ention, who nodded in agreement, their eyes revealed a shared sense of restlessness.
Silently, they began their assigned tasks.
In the face of work, all discomfort in the hearts of meticulous individuals ceases to be a problem.
Master Zhang's experiment concluded quickly, and he signaled Jack and Ention to proceed with today's work.
Office training of this kind is already a common practice for the two individuals. Due to various factors, often it's not feasible to wait until the equipment is formally deployed in the environment to guide customers in learning.
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Various disturbances in the office always make acoustical testing challenging. Fortunately, since it's just training, there are no specific accuracy requirements. The most important thing is to ensure that customers understand how to use it.
However, Jack has always been very disciplined. To ensure the accuracy of the testing, Jack must inform the customers that calibration before the test is a crucial step. Through calibration, the audio signal generator can precisely balance the output levels at various frequencies.

Precise individuals often find themselves accompanied by endless troubles due to their meticulousness. It seems that Jack's nightmare is about to come along with his precision.
After several attempts at calibration, all ending in failure, Jack's sense of tension seems to be bubbling up like water heating, producing more and more bubbles, growing larger and larger. Nervousness appears contagious, and Ention, pretending to be calm, comforts Jack, urging him to take it slow and try a few more times.
Everything was fine before departure. However, since inhaling the air of Qiantang, feeling the cool breeze of Qiantang, and utilizing the power supply of Qiantang, issues and bugs have followed?
Restart the computer, restart the software, restart the instrument, change the interface... but the problem persists, like an adhesive plaster stuck on a dog's fur.
Master Zhang, easygoing and approachable, never demands too much from the younger ones. He softly says on the side, "Don't worry, find the reason."
Sometimes, others' comfort can become an emotional catalyst.
Nervousness, like bubbles in boiling water, pervades Jack's body and mind; irritability, like spring shoots after rain, catalyzes Jack's discomfort, erupting from within.
After the boiling point of tension is reached, inspiration often follows with reason, though a bit delayed, problems are eventually resolved.
Suddenly, Ention realizes something. He takes out his cherished 1982 version sound level meter. "Let's first check if there's a problem with the office background noise," he skillfully turns on the instrument, fingers dancing on the keyboard.
"The background noise is less than 50 dB, calibration sound pressure level is 90 dB, and the signal-to-noise ratio is over 40. This... this is much better than the usual requirement of 25 dB signal-to-noise ratio."
"The microphone and sound source are also placed very close, just to avoid interference in the office. In theory, calibration should be smooth," Jack adds.
But he subconsciously wants to make an attempt, slightly increasing the calibration sound pressure level. Now, calibrating at 94 dB, a desperate measure.
Reluctantly, he presses the calibration button...
Calibration passes!

In a mix of surprise and confusion, Jack's training finally resumed.
Audio and acoustical measurements are complex endeavors. The equipment purchased by Master Zhang this time is a complete solution. Even for experts, it takes time to adapt to devices with different models and designs. Fortunately, with Master Zhang's rich experience, he can understand the entire process with just a brief explanation most of the time.
The morning time flew by, taking a short break, and the afternoon started with relentless work.
Master Zhang's professional questions, Ention's well-timed supplements, made Jack increasingly adept.
Finally, they reached the explanation of the last function.
FFT testing is not frequently used in Master Zhang's daily work. Jack intentionally saved it for last, thinking that even if he didn't explain it well due to fatigue, it wouldn't affect Master Zhang's work too much.
He skillfully introduced the measurement settings, clicked the mouse, and started the measurement.
At the moment the measurement results refreshed, everyone froze - on the vast spectrum, a peak stood out like Mount Everest.
At the 8Hz position, there was a sound with a sound pressure level as high as 88 dB!
For a moment, everyone's mood was complicated.
Master Zhang spoke first: "No wonder the previous calibrations didn't pass; the noise at this point is too loud!"
"The sound level meter can't measure it either. Ention's sound level meter can only measure down to 20 Hz, and it's A-weighted. There's really no way to deal with low frequencies."
This huge noise at 8 Hz seemed like a subsonic weapon! No wonder they felt uncomfortable the moment they entered the office.
Now it was Master Zhang's turn to be uneasy. Where did this strange subsonic wave come from? This is a national key laboratory. Could there be hostile forces with ill intentions, maliciously disrupting experimental activities?
When he voiced his thoughts, even Jack and Ention broke out in a cold sweat, looking around, feeling like they were under the constant surveillance of an enemy.
"No, the acoustics laboratory was built by me. I personally supervised the construction and installation of various equipment," Master Zhang said, suddenly slapping his forehead. "Upstairs is the subsonic laboratory. Could it be that they are conducting experiments today?"
With that, Master Zhang led Jack and Ention to sprint upstairs.

The graduate student on duty at the subsonic laboratory looked puzzled. With a few people in tow, he carefully checked all the equipment and found no opened signal sources.
The mood of the group plummeted again. They returned to the office, discussing other possible causes for the subsonic noise.
Jack's unease persisted. He silently prayed that it wouldn't be a problem with his own equipment. He reassured himself that instrument malfunction shouldn't cause such phenomena. No, it shouldn't, he thought.
The clock ticked away steadily, reaching four o'clock. Master Zhang's assistant approached quietly and reminded, "Dear professors, our laboratory also adheres to the national call for energy conservation and emission reduction. It's time to turn off the air conditioning!"
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Master Zhang has always been frugal. If it weren't for Jack and Ention's visit today, considering today's temperature, he wouldn't have turned on the air conditioning.
"Sure, turn it off, turn it off. Saving energy is everyone's responsibility."
After hearing this, the assistant pressed the air conditioning power-off button.
With a "beep" from the remote control, a peak flashed on the instrument's frequency spectrum. The air conditioning stopped running, and Jack also noticed that the subsonic wave at 8 Hz had disappeared …
In that moment, he and Ention felt an overwhelming sense of relief ...

"Laozi" says: "The great square has no corners, the great vessel is completed late, the great sound is rare, the great image has no form."
Although the noise was loud, its frequency was lower than that of a subsonic weapon. Inaudible to the human ear, but instruments don't lie, and Jack and Ention could deeply feel it in their bodies. Master Zhang, on the other hand, felt no discomfort. As he said, spending a long time in an environment had already made his body immune.
On the way back, Jack mentioned that after the tension, it felt like a breath of fresh air. Ention chuckled, saying, "When the spring wind brushes against your face, it will also sweep across your heart."
(The End)

Have fun!

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Author: Dukewill Source: blog.daisea.com

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