tbrattspeakers's posterous

« Back to blog

Learning Audio Basics

Audio is the range of acoustic vibrations that humans can hear as sound

Humans can generally hear a frequency range from 20 Hz to 20 kHz (1 Hz is 1 cycle per second)

Loudspeakers:

"An excellent loudspeaker will reproduce all musical pitches at the same loudness and with no significant differences in delay among the component frequencies."

SPL: Sound Pressure Level: Measure of the percieved loudness of a sound

3 Way Speaker: Uses a woofer, a midrange, and a tweeter. Divide audio energy into the system into 3 different frequency components, lows, mids, and highs

How a Speaker works:

Working parts of a dynamic speaker:

- Cone and its suspension

- Voice Coil

- Magnet

How it works:

"When an electric current flows through a wire, it sets up a magnetic field around that wire, and for a coiled wire the field is increased. If the coil of wire is located in an external magnetic field, provided by a magnet, the field of the coil interacts with that of the magnet to apply force to the coil. If the current is an alternating current, the field around the coil builds up and collapses in response to the frequencies of the current. In a speaker, this changing field interacts with the constand field of the magnet, causing the coil to move in response to the current. As the voice coil moves, it moves the cone, which creates pressure waves in the air near the cone. These pressure waves are heard as sound."

Sound Basics

All sound begins with a vibration. Vibrations set the air in motion. Every sound system is made up of three basic components, signal input, signal transfer and/or processing, and signal output. All of these components involve conversion points where energy is converted into another form of energy. With a sound system, the energy is generally converted from acoustical energy to electrical energy, and eventually back to acoustical energy. This is called transduction. All sound travels in waves. A sound wave is a chain of vibrating molecules. Energy waves must be transfered through matter, but it is only the energy that moves, not the matter. The molecules pass on the energy from one to another. A wave consists of a rise and fall of energy. Particles recieve the vibrations, and collide with other particles. After colliding, due to elasticity and inertia, the particles move back the same distance in the opposite direction; this is called rarefraction. The entire process creates a wave graph that looks like the sine graph. The amplitude is the height and depth of a sound wave. Sounds of higher amplitude are louder, compressing the air molecules more than those of lower amplitudes, softer sounds, do. Wavelength=Speed of sound/Frequency. Frequency is how many cycles pass a given point in one second. Generally, the higher the frequency of the sound waves, the higher the pitch.