Physics of Sound and Decibels

Sound propagates through air by creating fluctuations in air pressure caused by compression and rarefaction of air molecules.

The inverse square law describes how sound intensity decreases as the distance from the source increases. The intensity is inversely proportional to the square of the distance.

The decibel (dB) is a logarithmic unit used to measure the relative difference in intensity between two sounds. It's commonly used to measure sound pressure levels (dB SPL).

The human ear's sensitivity to sound is not linear, it's logarithmic: It's more sensitive to quieter sounds than louder ones.

The time difference between sound arriving at each ear helps us determine the direction of the sound source.

Wavelength is calculated by dividing the speed of sound by the frequency of the sound wave.

The human ear is a complex organ with a three-part structure (outer, middle, and inner ear) that transforms sound waves into nerve impulses that the brain interprets.

The process of converting sound waves into electrical signals in the ear, and then from electrical signals back to sound waves in a speaker, is called transduction.

The outer part of the ear, shaped like a funnel, that collects sound waves and directs them towards the ear canal.

A thin membrane that vibrates in response to sound waves, transferring the vibrations to the ossicles.

Three tiny bones in the middle ear - the malleus (hammer), incus (anvil), and stapes (stirrup) - that amplify and transmit vibrations from the eardrum to the inner ear.

A coiled, fluid-filled tube in the inner ear that converts sound vibrations into electrical signals that the brain interprets as sound.

Tiny hair-like cells located in the cochlea that are responsible for detecting different frequencies of sound. They convert mechanical vibrations into electrical signals.

A type of microphone commonly used for live events and rehearsals due to its rugged construction and ability to handle high sound pressure levels (SPL). It features a heavy diaphragm and coil that respond well to loud sounds and physical shock, making it ideal for recording instruments like drums, guitar amps, and even gunshots and explosions. Dynamic mics are relatively inexpensive and do not require phantom power.

A sensitive microphone that uses a thin, lightweight membrane to pick up sound. It typically requires phantom power for operation, making it suitable for recording recordings where high SPL is not a concern like vocals, acoustic instruments, and instruments that require a delicate and detailed sound capture.

The oldest type of microphone characterized by a thin, flexible metallic ribbon that vibrates in response to sound waves. This vibration induces an electrical signal in the ribbon, producing an audio output. They are often used in recording applications where a warmer, more natural sound is desired, like recording acoustic instruments and strings. They are also known for their wide frequency response and can provide a vintage, analog-like sound.

The process of converting changes in air pressure from a sound wave into electrical signals that can be processed and amplified. Different microphone types use different transduction methods. Dynamic mics rely on electromagnetic induction, condenser mics utilize electrostatic principles, and ribbon mics use electromagnetic induction.

The length of time it takes the persisting sound of reverb/reflections to decrease by 60dB below the original impulse level.

The initial reflections that bounce off surrounding walls, revealing the spatial characteristics of a room.

The time delay between the direct sound and the first early reflection. It contributes to the sense of space and depth.

When sound waves bounce between multiple surfaces, eventually reaching our ears. This creates a continuous stream of late reflections.

A method of creating artificial reverberation using a digital audio signal processing technique.

A type of digital reverb that simulates the sound of a real space by using a recorded impulse response.

A series of storage capacitors that carry the audio signal in sequence, creating a delay effect.

A device that creates delay by recording a signal to tape, playing it back, and then overwriting the recording with a new signal creating a feedback loop.

The ability to record multiple, independent tracks of audio simultaneously, allowing for layering and editing of sounds, greatly expanding creative possibilities in music production.

A process that creates a magnetic pattern on the tape representing sound waves, enabling playback.

A type of digital audio encoding that's used to capture and store audio information as discrete samples of the waveform.

A device that converts analog signals (like from a microphone) into digital signals (that a computer can understand) and vice versa. It's the bridge between your analog audio world and your digital recording world.

A method where audio is recorded linearly on a tape, played back in the same order, similar to a cassette.

A type of storage device that uses flash memory chips to store data. It has no moving parts, resulting in faster read and write speeds compared to traditional hard disk drives.

A type of audio recording where the sound waves are directly captured and stored onto a medium like magnetic tape.

A type of audio recording where the soundwave is converted into a series of numbers before being stored on a digital medium like a hard drive.

A type of audio processing tool that allows you to modify specific frequencies within an audio signal. It uses filters to either boost or cut frequencies.

A type of EQ that provides full control over the entire frequency range. This includes adjusting the level, frequency, and width (Q factor) of each band.

A type of EQ that gives more limited control than a fully parametric EQ. Typically, only mid-range frequencies have adjustable width (Q factor). Low and high frequencies have fixed or predefined shelving filters.

The difference between the loudest and quietest parts of a sound. Basically, how much the volume of a signal varies.

An audio processing tool that controls the dynamic range of a signal. It reduces the volume of loud peaks while increasing the volume of quiet parts.