(Audio Terms) test

Sound waves can be simple or complex. (Propagation) is the production or movement of something. Wave propagation is just a complex way of describing how sound waves move in the directions that they do. (Waveform) is a visual realization of sound waves, generally represented by a graph. These waveforms have different shapes and lengths including an s-shaped wave (the sine wave), square waves, triangle waves, sawtooth waves, rectangle waves, and even more complex shapes. When many simple waves create a complex wave, they are called (partials). More in depth, (overtones) are triggered when a fundamental pitch is sounded. (Harmonics) are other tones that occur when a pitch is heard because their frequencies double, and when they are doubled we hear the octave. (Wavelength) is measured in feet. A (sine wave) is a simple sound wave, generating a monotone. Waves travel at a (velocity) of approximately 1,130 ft/sec. (Wavelength = V/f) is the equation for calculating a waves length in feet. (Frequencies), synonymous with pitch, are measured in cycles per second and are represented as (hertz (Hz)). The (fletcher-munson curve) is a graphical representation of how we hear frequencies and how sensitive we as humans are to certain frequencies. Low end frequencies around 60hz are less audible to us than mid range frequencies around 1,000Hz. A (cycle) is one complete revolution of a sound wave from its positive state to its negative state, then back to 0. (Sound pressure waves) are the movement of sound waves through the air. Vibrations in the air are cause a change in air pressure. The sound pressure waves are measured by a microphone in air or a hydrophone in the water. Sound pressure waves are then transduced into electrical waves by the diaphragm of a microphone. (SPL or sound pressure level is a measurement of sound pressure in (decibels (dB)). Decibels are a measurement of the amplitude of frequencies. On the x – y axis, y represents dB, and x represents frequency. Amplitude is a measurement of how loud a frequency is. Frequencies have (harmonic content), which means that they are sonically attracted to one another. The higher the amplitude, the louder the sound is going to be. According to the laws of pressure, when pressure is doubled it will increase by 6dB. As the speed of sound changes, rarefaction occurs. (Compression) is the physical act of sound waves being squeezed into a certain space. Compression of sound increase as sound travels closer to the ear. (Rarefaction) happens when a sound changes environments, and is the actual bending of sound waves. This will change how sound is perceived by the ear. (Phasing) is when sound waves come in contact with one another. When sound waves cross at the same points, they are in (phase). If the signals cross each other at different points on the 0 line, they are considered to be out of phase, also called (phase shifting). When a signal is out of phase it may start sounding thinner and washy. (Acoustics) are the different characteristic qualities of sound in space. Many variables include but aren’t limited to: (reflections) of sound, which are sound waves that have bounced off of surfaces at various angles, known as (angles or incidence/reflection), and when waveforms come in contact with one another, it can create (standing waves) which are measured as a difference in air pressure, not to be confused with phase which occurs before reflections. (Flutter slap echo) is when a sound bounces off of many walls before reaching the transducer. After standing waves comes (room modes) which are disturbances in low end frequencies. Bass traps in the corner can minimize bouncing off of the back wall. (Acoustic isolation) is removing all the acoustics and sound characteristics of a room by insulating with walls of concrete, and layers of professional sound foam, creating a “dead” room sound. (Vocal booths) are a way of acoustically isolating a singer to capture the closest possible sound, and a dry sound as well, with little acoustics. (Reverb), or reverberation, is the tail end of a sound that you hear in the room after its release (explained later). If you yell in a bathroom, after you stop what you are hearing is reverb. If you do the same thing outdoors the woods, chances are you will not hear much of a reverb because the sound did not have surfaces to bounce off of. (Diffraction) of sound waves happens when the wave travels around a corner or down a hall, or through a doorway. (Diffusers) are devices made of wood or Styrofoam that deflect waves in a mathematical process that will keep them in phase and allow their cycles to complete. Every sound wave has an attack, decay, sustain and release creating a sound (envelope). The (attack) is the start of a transient, or sound, until it peaks in amplitude. The (decay) starts when the signal descends from its peak, and settles into the (sustain) portion of the envelope. This is where the sound wave has a smooth, gradual amplitude decrease. The (release) is the point when the signal comes back to 0dB. (Timbre) is the same as the quality of a sound. How a snare drum sounds versus how a bass or piano sounds are differences in timbre. (Beats) are the organization of sound in real time, on a grid in an aurally pleasing rhythmic fashion. (Frequency balance) is the attenuation and amplification in frequencies, also known as equalization. To attenuate a frequency means dip certain frequencies. An example of (direct sound) would be listening to headphones. Sound is only a couple of inches away from the eardrum, and sound is perceived obviously, directly. (Panning) refers to the stereo image, and hearing audio from the right or left perspective. Pan to the right or left to hear the right side of sound picked up by the microphone. (Near field monitors) are speakers that are placed near the producer, and (far field monitors) are placed significantly farther away. This allows the sound to develop more fully because it has more distance to travel to the ears.