The audiogram records the softest level of sound a person detects at each frequency, according to specific test criteria. These detectable amounts of sound are known as the person’s hearing thresholds. In a hearing test, the audiologist will most likely try to obtain thresholds for a number of different frequencies in each ear, often using various ways (air conduction and bone conduction) to deliver the sound to the ear.
Look at the blank audiogram graph below. Along the top of the the graph the numbers vary from 125 to 8000. These numbers reference frequencies, or different pitches of sounds.
The frequency of the sound refers back to the frequency of vibration from the sound source. The faster the pace of vibration, the higher the frequency from the sound. Sound frequency is usually measured in Hertz (Hz). A 250 Hertz (250Hz) tone seems like a deep, low-pitched horn. A little, tinkling bell features a high-pitch sound, probably measuring around 3,000 to 4,000 Hz.
Normal, healthy, young human ears can hear frequencies only 20Hz and as high as 20,000Hz. However, audiologists test hearing inside the range 250Hz to 8000Hz because a lot of the sounds of speech appear in this frequency range.
The intensity (loudness) of any sound is measured in decibels (dB). The decibel scale is shown on the side of the เครื่องช่วยฟัง. Audiologists need to use a variety of decibel scales, depending on how the sound is measured. For hearing tests, sound is generally measured in decibels of Hearing Level (dB HL). This decibel scale reflects the sensitivity in the normally-hearing human ear.
The softest sounds that young adults with normal hearing can detect in ideal listening conditions, is between zero and 20 ( – 20) dB HL, over the frequency range.
Conversational speech measured from one metre away is about 50 dB HL, though a few of the speech sounds will likely be around 35 to 40 dB HL.
Conversational speech measured from four metres away will likely be quieter, about 35 dB HL, with all the softer speech sounds only measuring around 20 dB HL.
Really loud rock concerts can measure 110 to 120 dB HL. Many individuals find sounds over 100 dB HL unpleasantly loud. The incidence of hearing loss increases since we age. Over half the populace aged between 60 and 70 use a hearing problems. This increases to greater than 70 percent of the over 70, and 80 percent of these older than 80.
Hearing loss among veterans
War veterans will probably are afflicted by hearing problems because of damage from noise exposure in their service. Hearing is definitely the second most typical medical problem reported by Australian war veterans and war widows, with 55 percent reporting hearing loss as a current medical problem.
What exactly is masking?
Throughout a hearing test, sound being delivered to one ear can sometimes be heard from the opposite ear. Normally, this is only a problem if there is a change in hearing levels between the two ears. Masking involves fpmaic a special noise into one ear while testing another ear. Audiologists use masking to find out which ear (cochlea) is hearing the test sound.
Sound heard in a room reaches both ears at very similar levels. When very young children are tested with sounds played away from a loudspeaker, the sound is assumed to get heard through the “better ear”, irrespective of which ear is nearest the loudspeaker.
Sound delivered by headphones or insert earphones is less likely to be cross-heard. Masking is usually only needed if there is a huge difference in hearing levels in between the ears. Sound delivered with a bone conductor is easily cross-heard from the opposite ear. Masking is frequently needed for bone conduction testing.