The audiogram records the softest level of sound an individual detects at each frequency, based on specific test criteria. These detectable levels of sound are referred to as the person’s hearing thresholds. During a hearing test, the audiologist will often try to obtain thresholds for many 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 make reference to frequencies, or different pitches of sounds.
The regularity of the sound refers back to the frequency of vibration in the sound source. The faster the rate of vibration, the larger the frequency in the sound. Sound frequency is generally measured in Hertz (Hz). A 250 Hertz (250Hz) tone sounds like an in-depth, low-pitched horn. A tiny, tinkling bell includes 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 most of the sounds of speech appear in this frequency range.
The intensity (loudness) of a sound is measured in decibels (dB). The decibel scale is shown on the side from the เครื่องช่วยฟัง. Audiologists need to use a variety of decibel scales, depending on how the sound is measured. For hearing tests, sound is normally measured in decibels of Hearing Level (dB HL). This decibel scale reflects the sensitivity from 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, across the frequency range.
Conversational speech measured in one metre away is about 50 dB HL, though a number of the speech sounds will be around 35 to 40 dB HL.
Conversational speech measured from four metres away will be quieter, about 35 dB HL, with the softer speech sounds only measuring around 20 dB HL.
Really loud rock concerts can measure 110 to 120 dB HL. Many people find sounds over 100 dB HL unpleasantly loud. The incidence of hearing difficulties increases as we age. Over half the populace aged between 60 and 70 use a hearing loss. This increases to greater than 70 percent of the older than 70, and 80 % of these over 80.
Hearing loss among veterans
War veterans will likely have problems with hearing problems as a result of damage from noise exposure during their service. Hearing is definitely the second most frequent medical condition reported by Australian war veterans and war widows, with 55 per cent reporting hearing problems as a current condition.
Precisely what is masking?
During a hearing test, sound being shipped to one ear can occasionally be heard by the opposite ear. Normally, this is only a concern if you have a change in hearing levels involving the two ears. Masking involves fpmaic a unique noise into one ear while testing one other ear. Audiologists use masking to find out which ear (cochlea) is hearing the exam sound.
Sound heard in a room reaches both ears at very similar levels. When very young kids are tested with sounds played away from 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 probably be cross-heard. Masking is normally only needed if you have a significant difference in hearing levels between the ears. Sound delivered by a bone conductor is definitely cross-heard from the opposite ear. Masking is often necessary for bone conduction testing.