Theory of Sound

 PART A                                                  

• What is sound?

Sound waves are the source of sound. When it passes via a medium and reaches the ear, it could be heard. All sounds are created by molecular vibrations. When a person strikes a drum or a cymbal, for instance, the object vibrates. Air molecular moves as a result of these vibrations. Sound waves go outward from their source. The eardrum vibrates once the vibrating air molecules are in contact of the ears. The ear bones vibrate in the same way that the object that generated the sound waves vibrated.

 

How sound is measured?

They are measured in frequency and decibels.

·       Frequency

The pace at which current changes direction every second is known as frequency. It's measured in hertz (Hz), which is an international unit of measurement that equals one cycle every second.

·    Hertz is a term used to describe a (Hz). A hertz is a unit of measurement that equals one cycle per second.

·       An entire wave of alternating current or voltage is referred to as a cycle.

·       A period is the amount of time it takes to create one complete cycle of a waveform.

·       The number of sound vibrations per second is measured by frequency.

A normal ear can hear a broad range of frequencies, measured in hertz (Hz), ranging from very low (20 Hz) to very high (20,000 Hz).

Humans all undergo presbycusis, or age-related hearing loss, as people get older. It's caused by the natural aging of the cells in our ears, which makes hearing higher frequencies more difficult.

While hearing loss is a natural part of growing older, wearing hearing protection when exposed to high decibel sounds can help to protect people hearing.

·       Decibels

The decibel, or dB, is a unit of measurement for sound intensity. Because the human ear is so sensitive, the decibel scale is a little strange. Everything from the fingertip barely brushing across the skin to a noisy jet engine can be heard by human ears. The sound of a jet engine is around 1,000,000,000,000 times stronger than the smallest audible sound in terms of power.

The smallest audible sound, almost absolute quiet, is 0 dB on the decibel scale. 10 dB is the difference between a sound that is 10 times stronger and a sound that is 10 times less powerful. 20 dB is a sound that is 100 times louder than almost absolute silence. 30 dB is a sound 1,000 times louder than almost absolute silence.

Common sound that people have heard and their decibels:

1. ·       Near total silence is 0 dB
2. ·       A whisper is 15 dB
3. ·       Normal conversation is 60 dB
4. ·       A lawnmower is 90 dB
5. ·       A car horn is 110 dB
6. ·       A rock concert or a jet engine is 120 dB
7. ·       A gunshot or firecracker is 140 dB

All of the above ratings were taken while standing in close proximity to the sound.

 

What is waveform?

A waveform is a representation of an audio signal or recording in the form of an image. It depicts the amplitude changes over a period of time. The amplitude of the signal is measured on the y-axis (vertically), while time is measured on the x-axis (horizontally).

Waveforms are displayed in most audio recording tools to provide the user a visual representation of what has been recorded. The audio was probably quite soft if the waveform is very low and not pronounced. If the waveform almost completely covers the image, the recording was either too "hot" or the settings were set too high. Changes in a waveform can also be used to determine when specific elements of a recording occur. When there is only a vocalist singing, the waveform may be minimal, but when drums and guitar are added, the waveform might grow considerably larger. This visual depiction allows audio producers to pinpoint specific sections of a song without having to listen to it.

 

• Types of waveforms

-       Sine

The fundamental waveform is what it's known. This is due to the fact that it is unadulterated: there are no “side effects” sounds. The only frequency people hear when playing a 440Hz sine wave is 440Hz.

Harmonics are the frequencies that appear as a side effect of a waveform. Certain waveforms produce harmonics, which are additional frequencies.

On actual analogue hardware synths, sine waves are less common. The fundamental reason is that they can't be filtered because they don't contain any harmonics, therefore attempting to filter them has the same effect as attempting to lessen their loudness.

 

-       Triangle

It has a similar appearance to the sine, but without the curviness. Instead, straight lines form triangle-like forms when they intersect. This makes the sound "brighter" than the sine wave, but thinner than the ones that come after.

Because of the harmonics, they don't sound as distorted as sine ones. The harmonics of triangle waves are unusual. They have the root note, the 3rd harmonic, the 5th harmonic, the 7th harmonic, and so on. As they travel further away from the fundamental frequency, the harmonics become smaller.

 

-       Square

Among the common periodic waveforms, the square waveform is likely the most severe. The harmonics are identical to those of the triangle waveform: Each “abnormal” harmonic (3rd, 5th, 7th, etc). The distinction is that square wave harmonics do not roll away as quickly as triangle waveform harmonics. 

 

-       Sawtooth

There's also the sawtooth. This waveform, which is named after saw blades, combines the linear ascent of the triangle waveform with the abrupt drop of the square waveform. It has a lot of harmonics since it includes even and odd notes.

When they run a bow across a violin's string, the contact between the two items causes the string to slip and catch, causing the string to vibrate in a sawtooth-like pattern.

 

PART B

Diegetic and non-diegetic sound

Diegetic and non-diegetic sound are the two types of audios that can be found in video games. Although there is some overlap between the two categories, non-diegetic sound mainly refers to the music, background ambience, and narrative commentary in video games.

Diegetic sound is the term used to describe the sound effects, background ambience, and character conversation in video games. Diegetic sound is any sound that comes from a source within the video game's universe. This is a sound that people would hear if they were within the game's universe.

 

Examples of diegetic sound;

1)     In Super Mario, Mario jumps and an iconic sound effect that followed the jump.

2)     In a racing game, pressing the acceleration button produces the sound of a car revving up.

3)     When a non-player character (NPC) speaks to the player, the player hears a voice actor's recording.

It's worth noting that diegetic sounds also can occur off-screen, where the sound source isn't apparent. The sound is implied here.

Even if the weapons and explosives are out of sight of the player, the sound of distant gunfire and explosions may be heard in the background of an FPS game.

 

A sound whose source is not visible on-screen or suggested to be present within the game's universe is known as non-diegetic sound. Non-diegetic sound is heard just by the player and is not part of the in-game world.

A narrator's commentary, an original soundtrack (OST), or SFX added for dramatic impact are examples of non-diegetic sounds.

 

Example of Non-diegetic sound:

1)     The player in Grand Theft Auto is flung from a car and dies, resulting in the sound effect "wasted."

2)     As attackers approach the player in Space Invaders, the background music speeds up.

In Halo 3's final mission, a portion of the OST plays in the background to heighten the tension as the Master Chief flees the Ring.