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International standards organizations (ISO, [2] ANSI [3] and ASA) recognize the need to objectify judgements on the amount of ambient noise in enclosed spaces, and provide us with definitions for various noise curves. [4] The ANSI/ASA S12.2-2008 standard, for example, recommends an NC value of 25-35 for schools and 15-18 for concert halls. [5]
Psychoacoustic tuning curves can be measured using the notched-noise method. This form of measurement can take a considerable amount of time and can take around 30 minutes to find each masked threshold. [10] In the notched-noise method the subject is presented with a notched noise as the masker and a sinusoid (pure tone) as the signal.
Noise curve; Noise dosimeter; Noise map; ... Sound Level Label Examples; Sound level meter; Sound limiter; Sound power; Sound pressure; Speech interference level ...
Pre-emphasis is commonly used in telecommunications, digital audio recording, record cutting, in FM broadcasting transmissions, and in displaying the spectrograms of speech signals. One example of this is the RIAA equalization curve on 33 rpm and 45 rpm vinyl records. Another is the Dolby noise-reduction system as used with magnetic tape.
Noise that has a frequency spectrum of predominantly zero power level over all frequencies except for a few narrow bands or spikes. Note: An example of black noise in a facsimile transmission system is the spectrum that might be obtained when scanning a black area in which there are a few random white spots. Thus, in the time domain, a few ...
Simultaneous masking occurs when a sound is made inaudible by a noise or unwanted sound of the same duration as the original sound. [2] For example, a powerful spike at 1 kHz will tend to mask out a lower-level tone at 1.1 kHz. Also, two sine tones at 440 and 450 Hz can be perceived clearly when separated.
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For example, aging typically leads to hearing thresholds which get poorer as test frequencies get higher. [10] Noise induced hearing loss is typically characterized by a "notch" in the audiogram, with the poorest threshold occurring between 3000 and 6000 Hz (most often 4000 Hz) and better thresholds at lower and higher frequencies. [11]