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A typical top-end speaker, driven by a typical 100watt power amplifier, cannot produce peak levels much above 105 dB SPL at 1 m (which translates roughly to 105 dB at the listening position from a pair of speakers in a typical listening room). Achieving truly realistic reproduction requires speakers capable of much higher levels than this ...
The measure of the low frequency (many tens of Hz) noise contributed by the turntable of an analogue playback system. It is caused by imperfect bearings, uneven motor windings, vibrations in driving bands in some turntables, room vibrations (e.g., from traffic) that is transmitted by the turntable mounting and so to the phono cartridge.
Dynamic range is a measure of how small you can measure a signal relative to the maximum input signal the device can measure. Expressed in decibels, the dynamic range is 20 log (Vmax/Vmin). For example, a device with an input range of ±10 V and a dynamic range of 110 dB will be able to measure a signal as small as 10 μV.
In the simplest form, subtract the height of the voice-coil winding from the height of the magnetic gap, take the absolute value and divide by 2. This technique was suggested by JBL 's Mark Gander in a 1981 AES paper, [ 23 ] as an indicator of a loudspeaker motor's linear range.
Required for measuring the acoustics in buildings is a signal generator that provides pink or white noise through an amplifier and omnidirectional speakers. In fact, the omnidirectional speaker, or sound source, should provide an equal dispersion of sound throughout the room. To achieve accurate measurements, sound should radiate evenly.
Room modes are the collection of resonances that exist in a room when the room is excited by an acoustic source such as a loudspeaker. Most rooms have their fundamental resonances in the 20 Hz to 200 Hz region, each frequency being related to one or more of the room's dimensions or a divisor thereof. These resonances affect the low-frequency ...
A digital thermometer reading an ambient temperature of 36.4°C (97°F) in an unventilated room during a heat wave; a high indoor temperature can cause heat exhaustion or heat stroke in a person. The World Health Organization in 1987 found that comfortable indoor temperatures of 18–24 °C (64–75 °F) were not associated with health risks ...
In air at ambient temperature, z 0 = 410 Pa·s/m, hence the reference value I 0 = 1 pW/m 2. [7] In an anechoic chamber which approximates a free field (no reflection) with a single source, measurements in the far field in SPL can be considered to be equal to measurements in SIL. This fact is exploited to measure sound power in anechoic conditions.