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Pure-tone audiometry is the main hearing test used to identify hearing threshold levels of an individual, enabling determination of the degree, type and configuration of a hearing loss [1] [2] and thus providing a basis for diagnosis and management.
The intensities displayed on the audiogram appear as linear 10 dBHL steps. However, decibels are a logarithimic scale, so that successive 10 dB increments represent greater increases in loudness. For humans, normal hearing is between −10 dB(HL) and 15 dB(HL), [2] [3] although 0 dB from 250 Hz to 8 kHz is deemed to be 'average' normal hearing.
The ear's shape also allows the sound to be heard more accurately. Many breeds often have upright and curved ears, which direct and amplify sounds. As dogs hear higher frequency sounds than humans, they have a different acoustic perception of the world. [24] Sounds that seem loud to humans often emit high-frequency tones that can scare away dogs.
An audio frequency or audible frequency (AF) is a periodic vibration whose frequency is audible to the average human. The SI unit of frequency is the hertz (Hz). It is the property of sound that most determines pitch. [1] The generally accepted standard hearing range for humans is 20 to 20,000 Hz.
There is also high frequency Pure Tone Audiometry covering the frequency range above 8000 Hz to 16,000 Hz. Threshold equalizing noise (TEN) test; Masking level difference (MLD) test; Psychoacoustic (or psychophysical) tuning curve test; Speech audiometry is a diagnostic hearing test designed to test word or speech recognition. It has become a ...
The frequency range often specified for audio components is between 20 Hz to 20 kHz, which broadly reflects the human hearing range. Well-designed solid-state amplifiers and CD players may have a frequency response that varies by only 0.2 dB between 20 Hz to 20 kHz. [4]
The first research on the topic of how the ear hears different frequencies at different levels was conducted by Fletcher and Munson in 1933. Until recently, it was common to see the term Fletcher–Munson used to refer to equal-loudness contours generally, even though a re-determination was carried out by Robinson and Dadson in 1956, which became the basis for an ISO 226 standard.
The sound level generated is 94 dB, which corresponds to a root-mean-square sound pressure of 1 pascal and is at a frequency of 1 kHz where all the frequency weightings have the same sensitivity. For a complete sound level meter check, periodic testing outlined in IEC61672.3-2013 should be carried out.