The audiogram records the softest level of sound a person detects at each frequency, based on specific test criteria. These detectable amounts of sound are known as the person’s hearing thresholds. During a hearing test, the audiologist will most likely attempt to obtain thresholds for a number of different frequencies in each ear, often using different methods (air conduction and bone conduction) to offer the sound to the ear.
Consider the blank audiogram graph below. Along the top of the the graph the numbers range from 125 to 8000. These numbers make reference to frequencies, or different pitches of sounds.
The regularity of a sound means the frequency of vibration of the sound source. The faster the pace of vibration, the higher the frequency of the sound. Sound frequency is normally measured in Hertz (Hz). A 250 Hertz (250Hz) tone looks like a deep, low-pitched horn. A small, tinkling bell includes a high-pitch sound, probably measuring around 3,000 to 4,000 Hz.
Normal, healthy, young human ears can hear frequencies as little as 20Hz and as much as 20,000Hz. However, audiologists test hearing within the range 250Hz to 8000Hz because a lot of the sounds of speech happen in this frequency range.
The intensity (loudness) of any sound is measured in decibels (dB). The decibel scale is shown down the side in the เครื่องช่วยฟังดิจิตอล. Audiologists need to use many different decibel scales, for the way 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 younger people with normal hearing can detect in ideal listening conditions, is between zero and 20 ( – 20) dB HL, across the frequency range.
Conversational speech measured in one metre away is around 50 dB HL, though a few of the speech sounds will 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. Lots of people find sounds over 100 dB HL unpleasantly loud. The incidence of hearing difficulties increases while we grow older. Over half the population aged between 60 and 70 possess a hearing loss. This increases to a lot more than 70 percent of those over 70, and 80 percent of the older than 80.
Hearing problems among veterans
War veterans will probably have problems with hearing problems due to damage from noise exposure in their service. Hearing is definitely the second most frequent medical condition reported by Australian war veterans and war widows, with 55 percent reporting hearing problems being a current condition.
Precisely what is masking?
During a hearing test, sound being shipped to one ear can often be heard through the opposite ear. This is usually only a problem if there is a change in hearing levels in between the two ears. Masking involves fpmaic an exclusive noise into one ear while testing the other 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 kids are tested with sounds played out of a loudspeaker, the sound is assumed to become heard by the “better ear”, no matter which ear is nearest the loudspeaker.
Sound delivered by headphones or insert earphones is less likely to be cross-heard. Masking is generally only needed if you have a big difference in hearing levels between the ears. Sound delivered by a bone conductor is easily cross-heard from the opposite ear. Masking is frequently required for bone conduction testing.