Stereophonic sound for music = Is it okay to call it high-quality sound?

So that "familiar taste" and "unusual taste" are similar but different.

In June 2021, Apple released its spatial audio feature, and Sony began licensing 360 Reality Audio earlier this year. Words such as spatial, three-dimensional, and 3D are trending in the audio world these days.

These words I really started to hear. As the name suggests, it is a technology that allows you to hear music in three dimensions, but words alone don't make sense. But when you listen to it, it's so different that you can tell that it's clearly different from what you've heard before! I would say that you can feel the depth, top and bottom, front and back, rather than the surface of the sound.

…But does stereophonic sound really contribute to sound quality? Is it okay to express that the music that I always listen to has high sound quality because it has stereophonic sound?

This article is about thinking about that point, and in conclusion, it is a story that one evaluation axis that is different from the conventional linear (straight) high-quality sound competition has been born. Just like digital cameras and televisions, the competition for higher pixels has hit a ceiling.

What is Stereophonic Sound?

I first learned about stereophonic sound around 2010 on Nico Nico Douga. There was a music video that used a technology called "holophonics," and when I listened to the sound through headphones, it felt like the back of my brain was being stroked, and I remember being deeply moved. It's a technique that Pink Floyd also used.

Holophonics itself is one of the trademarks of 3D sound technology. There are many similar technologies related to stereophonic sound, for example, the familiar binaural recording of ASMR is also stereophonic, the 3D audio of "Fortnite", and the movie sound Dolby Atmos. Each definition is different, but it is wrapped in stereophonic sound. There are also different methods such as surround sound, spatial sound, and binaural.

The history of stereophonic sound can be traced back to the advent of stereophonic recording in 1931, but it may be interesting to unravel the world's first two-channel sound system, which was unveiled at the Opera House in 1881. However, in the modern sense of "multi-channel stereoscopic audio experience", there are not many environments where ordinary people can listen. That's what you can enjoy in home theaters and movie theaters with many speakers. Even in the 2010s, I think that what was uploaded to the net was accepted as a part of technical evaluation, or as amazing content. However, in recent years this has changed.

Soundbar for example. There are many soundbars that can reproduce Dolby Atmos, an audio format often used in movies. It is also called virtual 3D surround in the sense that it reproduces surround sound with multiple speakers. JBL, SONOS, Sennheiser and others have also released soundbars that support virtual 3D surround. Especially the three-dimensional effect of Sennheiser was amazing.

Surround headphones and earphones have been around for some time. It may be technically easier to create a sound that delivers sound directly to the ear than a speaker that emits space (head-related transfer function, impulse response, etc.). There are a lot of 7.1ch gaming headphones out there, and AirPods MAX, where faith is tested.

Let's talk: Does the shape and furniture of the room change the way you hear?

The sound emitted from the speakers is reflected off the walls and ceiling of the room, or absorbed by the fabric and furniture. In this case, the correct sound cannot be heard, so room acoustics measurements are used to measure how the room reverberates and compensate the speakers. If there is unnecessary resonance or the bass is attenuated, the sound will be uneven. These techniques are common in music production and home theater, but they also find applications in stereophony. In other words, it uses the echoes of the room to make the sound appear three-dimensional.

By using reflexes, you can hear sounds behind and above you. How much sound wave is reflected, how far is the distance to the wall, the measured wave is picked up by the microphone, analyzed, and tuned so that it intersects well at the listening position. You're so smart!

Was it intentional?

Stereophonic sound is indeed a "startling" technology. But is it okay to evaluate stereoscopic sound as high-quality sound? Aren't you just excited by unfamiliar stimuli? Or is it okay to rank three-dimensional sound > two-dimensional sound?

When evaluating headphones and earphones, terms such as sound field, resolution, presence, localization, and graininess are often used. It is also said that a good playback device can tell the position of the sound. If you listen to the orchestra, the violin is in the foreground, the wind instruments are slightly in the back, and the bass sounds from the right through the entire hall.

In the case of an orchestra, we sometimes record the actual concert with a microphone hung from the ceiling of the hall. In this case, the playback side is required to "how can it be heard in the same way as in a hall (pseudo-experience)". The microphones in the hall not only record the sound of the performers, but also the reverberation and reverberations of the entire hall, which leads to a unique live feeling. Famous concert halls have wonderful reverberations, and some DAWs (music production software) reproduce the reverberations of specific halls. When recording, I set up a banging mic, so it's a lot of recording in space.

In other words, in the case of orchestral sound sources, they are recorded in 3D, so listening to them in 3D is more like that.

What about general pop and electronic music? For example, in a 3-piece band, you have a guitar, drums, bass, and track, and the sound recorded on line for each part doesn't include spatial reverberations (assuming you don't use spatial effects). In many cases, each instrument is recorded for each part and adjusted during mixdown, but it is easier to adjust the sound if it is recorded on line rather than with a mic, as there are no unwanted reverberations. Even if you want a spatial reverberation, it is difficult to achieve the desired reverberation because the reverberation varies greatly depending on the shape of the room. If it's a home record, it's even more so.

In the mix, the expression of depth and three-dimensionality is a very important element. Sound with reverb, sense of distance with compression, sense of separation with EQ, and so on. The sound source is completed through endless mixing work, but the sense of space created in this way is, so to speak, virtual.

I vaguely remember that Mr. Yukihiro Takahashi of YMO said something along the lines of, ``Recent sound sources are too beautiful. I'm sorry if I made a mistake. For example, when recording a guitar performance, if you record it with a microphone, the resonance of the wall and other instruments will overlap. It's noise, but it's also groove. Some software sound sources can even adjust this kind of fog.

If you record with a microphone, it is a three-dimensional sound source that records the time and space of the instrument playing, and it has the meaning of returning the sound source to three-dimensional space. You can also enjoy the sound unique to the studio. But isn't there something wrong with reviving sound sources that weren't originally recorded in spatial units as stereophonic sound? That's what I think.

Take a 3D movie analogy. You can watch images that pop out of the screen by wearing special glasses. However, for that reason, the production side needs to shoot on the premise of a stereoscopic movie (there are movies that have been converted from 2D to 3D, but it is not possible to shoot parallax). If a movie that was filmed normally were to be made three-dimensional by the movie theater, wouldn't that be a different experience than what the filmmaker intended?

Let's talk: where is the right sound?

In music production, mixdown is the process of combining separately recorded tracks such as guitars, vocals, and bass into one. Mixing is a terrifyingly deep process with no right answer. There are several reasons.

・Preferences differ depending on the creator

・In the end, the way you hear will change depending on the device you listen to

・After all, there is no optimal solution

Professionals have to consider the delivery date and playback environment, but for amateurs, it's a never-ending journey. In the past, there was a time when I tried mixing at Tamori Club. It is the mix that comes out clearly. And the painstakingly crafted mixes are different depending on whether you listen to them on AirPods or JBL speakers. Ultimately, I will check with various playback devices, but even then I can't completely control what the listener hears. If it's a modern reference, AirPods would be the greatest common divisor.

Are non-stereoscopic images inferior?

3D movies and stereoscopic photographs have been tried since the 19th century. I feel that the admiration of wanting to face creations on the three-dimensional axis that we humans live in continues to today's VR space. On the other hand, three-dimensionalization and three-dimensionalization in listening to music is a story, but there is also a method to create a three-dimensional effect by arranging sound sources in a virtual space during mixing and creating a sense of front and back and up and down from the position where the sound is produced. Yes (also called object-based, such as sound sources for Dolby Atmos).

Currently, most sound sources are not mixes with stereophonic sound. This is where Sony's 360 Reality Audio is revolutionary. From the time of production, the position, distance, angle, etc. of the sound source are arranged in space, making it a format that makes it easy to convert even past sound sources into 360 Reality Audio. (requires multitrack or stem data). Apple's spatial audio, on the other hand... what's the logic? Object-based if you apply Dolby Atmos technology?

No matter what method you use, if the service side and the speaker side are compatible, they will play the sound source with stereophonic sound. As I mentioned in the mix example, whether or not it matches the production intention is difficult in the first place, so it should be ignored unless you are a person who is extremely focused on the principle of original sound. let me try.

What I think is "What about that?" Isn't the difference there not about the superiority or inferiority of the score, but a form change difference? Both V2 Assault and V2 Buster are good, and big toro and medium toro are different depending on whether you like fat in the first place. Isn't that kind of horizontal difference the stereophonic sound?

But when stereo and surround came along, mono didn't die, right? The warm, straight sound you hear from a monaural radio-cassette player isn't inferior to a speaker with a sense of presence. If it's the same theory, why would you dare to detune a photo with a crisp resolution to make it look like a film!?

I want to say that it is wrong to judge the presence or absence of a three-dimensional effect like the amount of resolution. Ultimately, the resolution of digital sound sources approaches that of real acoustics, but it's clear from the fact that Famicom music is still loved that low-bitrate sound sources and music aren't bad.

Stereophonic sound is like a 'fourth taste'?

This time, when I was thinking about stereophonic sound, I was wondering if there was anything similar, and I thought it might be similar to Koransei from the cooking manga "Iron Pot Jean". ,and. Huang, a Chinese culinary genius, had the talent to control the 4th element, texture, in addition to the 3 major elements of cooking: five tastes, aromas, and aesthetics. He's mastered the fourth factor, so he can't win. With such super reasoning, I cornered the main character Jean.

In other words, we created an evaluation axis that had never existed before. If texture = 3D sound, the competition for high-quality sound, which used to be based on bit rate and sampling frequency, has changed to a new evaluation axis called 3D sound, which has changed the way audio products compete. It has changed.

Just as Jang devised a unique texture after seeing Huang's food that manipulates the texture, manufacturers such as Apple and Sony have created a new auditory experience called stereophonic sound, and other manufacturers have also created their own. It is beginning to surprise users with its unique stereophonic sound. Stereophonic sound, which is currently minor, may become mainstream if users want it. I've already mentioned that the term stereophonic sound is complicated, but that's probably why it's called spatial audio, 360, or 3D surround. That's really confusing though.

If you think about it, it's true that the challenge of realistic resolution performance has hit a plateau in any genre, where high sound quality is as close to acoustic as possible. Earphones that are close to 30,000 yen all have good sound, and rather than having them choose according to their sound preferences, I feel that it would be better to be told that stereophonic sound can be used in a different way. There is no doubt that stereophonic listening is a new experience, and considering the current world that emphasizes individual experiences, it may be an evolution that has come about as much as possible.

However, it's a rigid fundamentalist thought that makes me shudder at the scheme that sounds can be heard three-dimensionally = high sound quality... But when I listened to Sony's "SRS-RA3000" at a mass retailer, I was surprised by the difference... No, the difference is not whether it's easy to listen to or not, and I want to review the need for 3D rendering depending on what kind of content I listen to. , hmmm...

What do you guys think of stereophonic sound?