Diary of a Criminal Investigator-Chapter 281: Voiceprint Identification Analysis Results

Chapter 281: Chapter 281: Voiceprint Identification Analysis Results

The case is an old one, so there’s no need to rush.

They heard Lu Chuan could do voiceprint analysis over at the High-speed Rail New District, so they sent it over to give it a try.

The spectrograph arrived earlier than expected, delivered to the Criminal Investigation Team on Wednesday afternoon.

Qin Yong arranged for the purchase of a domestic spectrograph. This device was previously made abroad and it’s only been a couple of decades since domestic research and manufacturing began.

Even after domestic production, the price of this thing isn’t cheap.

Among the dozens of pieces of equipment in the Crime Scene Investigation lab, it’s considered one of the more valuable ones.

There aren’t many people in the Crime Scene Investigation, but in terms of total assets for the entire Criminal Investigation Team, the Crime Scene Office can claim first place.

There are nearly forty pieces of equipment, big and small.

Although Lu Chuan had received system rewards for intermediate voiceprint identification and analysis skills, which included using the spectrograph in the skillset experience,

in practice, today was also the first time for Lu Chuan to see the actual spectrograph.

"This little thing... costs three hundred thousand?"

Old Bai looked at the manufacturer’s staff assembling and adjusting the instrument and clicked his tongue in wonder.

The thing is small, three small rectangular boxes connected by various wiring harnesses.

Among them, two are filled with buttons, and at a glance, there seem to be dozens.

This thing clearly isn’t particularly easy to operate. With so many buttons, it probably requires some time to learn how to understand it.

The other one has a screen window in the lower-left corner, and just by looking at the color, you know it’s black and white.

"Are the results seen here?"

Lu Chuan nodded: "This is currently the most advanced spectrograph available, capable of direct recording and analysis of target sounds, as well as importing audio for analysis."

Typically, a spectrograph uses dedicated microphones to capture sound and further perform real-time analysis.

This spectrograph is different; it allows for audio data to be directly imported into the system, which avoids the pollution from secondary recording and significantly improves analysis accuracy.

"When did you learn to use this?"

Lu Chuan rubbed his head: "Came across it in college; we had this kind of spectrograph in our lab."

Ah, college.

Lu Chuan truly didn’t go to college for nothing.

Yang Sen suddenly started to fantasize, hoping that if his son could learn half, no, even just one-third of what Lu Chuan did in college, he wouldn’t do badly out in society.

The setup of the equipment was done quickly, mainly testing to see if the equipment was in good condition.

The staff themselves don’t do voiceprint analysis; they just follow the manufacturer’s preset procedures, connect the harness, test with different sounds, and then compare the analysis results with standard images.

After a few procedures, they confirmed there were no issues with the machine, and once Liu Guodong signed the acceptance form, it was considered complete.

The procurement of the Criminal Investigation Team’s goods isn’t just a matter of picking who they want to buy from; it’s all centralized online purchasing.

It’s just that the purchasing party lists items based on the needs of the Criminal Investigation Team that they don’t have.

Of course, there is no discount on the price, absolutely no factory discount price.

"Master, you go on upstairs and rest a bit; I’ll analyze that recording and then head over." 𝒇𝒓𝙚𝒆𝔀𝓮𝓫𝒏𝓸𝙫𝓮𝓵.𝓬𝙤𝙢

"No need, no need, we’ll just watch here, never seen a voiceprint identification analysis before, we’ll also learn how it’s done."

Liu Guodong waved his hand, now familiar, there’s no need to sneak around and learn on the sly.

Lu Chuan didn’t mind, this thing is hard to learn.

Voiceprint identification analysis isn’t just a matter of entering the sound into the machine’s input end and getting a result on the other end.

Of course, you can do it that way, but the spectrum analysis for everyone’s voice would be roughly similar.

It couldn’t reflect uniqueness; this thing would just be an expensive toy.

Lu Chuan had to extract different frequencies of sound through equipment adjustment, then perform comparative analysis.

Male and female voices sound different, mainly determined by the frequency and fullness of the sound.

Generally, female voices have higher frequencies, while male voices have lower frequencies.

The fullness of female voices in higher frequency ranges is stronger, making them sound crisp.

The fullness of male voices in lower frequencies is stronger, making them sound deeper.

Analyzing the voices of four people isn’t very fast; Lu Chuan needed to repeatedly input the raw sound, adjust the equipment, and conduct analysis on various frequencies.

In the eyes of Liu Guodong and others, Lu Chuan seemed to be constantly rotating buttons and taking pictures of the analyzed spectrogram.

In fact, this instrument can print out sound spectrograms, but Lu Chuan didn’t do that.

Printing the spectrogram is for comparison; taking pictures with a phone is also convenient for comparison.

After tinkering for about an hour, Lu Chuan finally turned off the spectrograph.

"All done?"

"Pretty much, we’ll get the report shortly."

The spectrograph only performs spectral analysis on the sound, and isn’t advanced enough to prepare a report of the analysis results.

Successful voiceprint identification analysis results often provide more information than expected.

Such as age range, weight range, residential area range, dietary habits, etc., all can be obtained through voiceprint analysis.

The voiceprint analysis done in the underground lab just now was basic data analysis, the foundational data for conclusions.

What Lu Chuan is doing now is the essence of the entire voiceprint analysis.

Lu Chuan numbered the voices in the recording in the order of their appearance.

"Voice number one, Mandarin Level 2 Grade B, Dingzhou accent, aged between thirty-five to forty-five years, weighing around sixty kilograms."

"Voice number two, Mandarin Level 3 Grade A, Southern Zhezhou accent, aged between forty to forty-five years, weighing around ninety kilograms, with a habit of consuming spicy food."

"Voice number three, Mandarin Level 2 Grade A, Haizhou accent, aged between thirty-five to forty years, weighing about seventy kilograms."

"Voice number four, Mandarin Level 2 Grade B, Haizhou accent, aged between twenty to twenty-five years, weighing about fifty kilograms, with vocal cord scars, likely repaired five years ago."

Liu Guodong looked puzzled holding Lu Chuan’s voiceprint identification analysis report.

What’s going on?

Just by listening to the voice, you can determine age?

Fine, not talking about the accent, even without a professional, Liu Guodong can distinguish the Haizhou accent from other local ones.

The age also makes sense; people’s voice pitch and tone differ across age brackets.

But weight?

How does one analyze weight from sound?

Seems absurd?

Let alone the consumption of spicy food, can that be heard too?

The last one is even more ridiculous. Liu Guodong had listened to that recording countless times.

The last female voice was extremely hoarse, sounding like a voice of a middle-aged woman in her forties or fifties.

How could it possibly be a twenty-something young woman?

Old Bai and Yang Sen also crowded over, seeing Lu Chuan’s analysis report conclusions.

"Lu, is this for real?"