![]() ![]() The fidelity of a column can be no better than that of the individual speakers. The advantage of a column is its simplicity and being visually unobtrusive. Their intended application is for announcements and background music. Often seen in churches, shopping centres, travel terminals, gymnasiums etc. The majority of traditional column systems consist of a vertical row of small speakers. A natural horizontal line source of sound energy is a motor way or a beach. In reality, large line array systems approach this on a limited scale. Sound energy only decreases by 1/2 per double the distance (-3dB/2D). In theory an infinite vertical line source of sound energy can only disperse horizontally. Sound energy dispersing from a point source decreases by 1/4 per double the distance. The explanation below is basic and will be expanded in greater detail when the other chapters in this education site are completed. To understand how sound disperses from a system requires us to think of Frequency as its wavelength. It is often generalised as 344 meters per second or 1ft / milli-second. ![]() Velocity of sound is dependant on temperature, atmospheric pressure and humidity. This reduces intelligibility and limits the overall high frequency energy. Wavelength distances between adjacent boxes and speaker stacks generate intense lobe and comb filter distortion, throughout the music spectrum. Inter-modulation compounds as the power increases (inter-cluttering within the music). Speaker systems set up in clusters for high power cause compromises that restrict fidelity and linear dynamic power handling (sound quality changing in reference to power). (b) 2 15in speakers, four 8in speakers and hi-frequency horn. Each cabinet can be compacted with variations of. This enables practical economic management. The numbers of cabinets is varied to suit the application. Large Clusters For large auditoriums, speaker cabinets are stacked in convex clusters, or vertical lines above the audience. Grouping many speakers together to achieve power is always a compromise that reduces fidelity, regardless of the arrangement the speaker are grouped in, or marketing hype. Theoretically, sound from a single point gives better fidelity. A group of 4in speakers do not sound like a 15in speaker.ī. Also a section of violins do not sound like a cello. Increasing the size of a speaker or musical instrument does not necessarily make it louder, but shifts its efficiency lower in the musical range. Natural frequency of the air-filled tube.A. To see the effect of helium on voice quality, calculate the ratio of the nth natural frequency of the helium-filled tube to the $nth$ The quality of the voice depends on the harmonic frequencies generated by the tube larger frequencies lead to higher-pitched voices. To see why this occurs, assume for simplicity that the voice is generated by the vocal cords vibrating above a gas-filled cylindrical tube that is open only at one end. Helium, however, has the effect of giving the voice a high-pitched quality, like that of Donald Duck’s voice. This danger is for divers to breathe a mixture containing only helium and oxygen. Divers working in underwater chambers at great depths must deal with the danger of nitrogen narcosis (the “bends”), in which nitrogen dissolves into the blood at toxic levels. ![]()
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