Audiometric Test Procedures 101 This information is meant to help you better understand the various test procedures as well as some of the terms you might see on an audiometric report. By Larry Medwetsky individual could, in fact, exhibit nor- In the previous issue of Hearing mal hearing acuity across these three Loss Magazine, I provided an over- Anyone who has ever had their frequencies, yet, exhibit a significant view concerning hearing threshold hearing tested should know how hearing loss in the higher frequencies results as recorded on the audiogram to read the audiogram, but that’s (3000-8000 Hz). Thus, it is important and an explanation of the pure-tone easier said than done. Hopefully, to examine the SRT in the context of audiogram. In this article, I will after reading this article you will the other audiometric test findings. describe various test procedures have a greater understanding of the Speech Awareness Threshold that are typically administered in principles discussed and use your (SAT): an audiometric evaluation and what knowledge going forward—be it in Compound words are pre- information the tests provide. reviewing hearing test results you sented, the goal being to determine already have or when discussing your the softest level one can detect the Audiometric Test Procedures results at your next hearing test. presence of words. This test is often Pure-tone Audiometry: Tones of used when an individual’s hearing loss different frequencies are presented; the is so great that the person is unable goal is to find the softest sound level relatively flat hearing losses, and the to recognize/repeat the words, yet is which one can hear (threshold) the average of 500 and 1000 Hz for those aware that words have been presented. different tones. This test is typically with significantly sloping hearing Similar to the SRT, a person could administered in one of two ways: air- losses (i.e., the individual’s hearing present with an SAT value within the conduction audiometry—involving thresholds drop sharply with increas- normal range, yet exhibit significant the use of head/ear phones; and, bone- ing frequency). hearing difficulty. conduction audiometry—involving Speech Reception Thresholds For example, an individual might the placement of a vibrating device on often serve as a reference for the au- have a hearing threshold of 15dB HL a person’s skull. diologist in determining presentation at 250 Hz and reveal an SAT of 15dB By comparing the results from levels for other speech tests and as a HL, but for frequencies 500 to 8000 both procedures, one can determine if reliability check concerning the con- Hz exhibit a significant hearing loss. there is a conductive component pres- gruency of pure-tone test results and ent (some form of barrier interfering the SRT; that is, if the SRT and pure- Word Recognition Score (WRS): with the transmission of sound from tone averages are within 10 decibels of Single syllable words are presented at the outer/middle ear to the inner ear). each other, audiologists can state with one or more listening levels: everyday In addition to any inner ear hearing loss certainty that the results agree with conversational level (approximately that might be present, the presence of each other. 50 dB HL); and, comfortable listen- a conductive component would result An SRT is considered to be ing (MCL) level. For most individuals in air-conduction thresholds over and normal if it falls in the range of -10 with a hearing loss the MCL is louder above the bone-conduction thresholds. to 25dB HL (Hearing Level). Even than the everyday conversational level though an individual might obtain a Determinations of word recogni- Speech Reception Threshold value within this normal range, this tion scores typically entail the presen- (SRT): Compound words (words does not always mean that he has tation of 25 or 50 words to each ear comprised of two smaller words, such completely normal hearing acuity. For separately and calculating the percent as cow-boy) are presented, the goal example, it is possible that the individ- of words correctly repeated. This test being to find the softest sound level ual’s thresholds in one ear are 15dB, can be administered either in quiet at which one can hear and repeat ap- 25dB, and 35dB HL at 500, 1000 Hz, (without any competing noise) or proximately one-half of the compound and 2000 Hz respectively. The average in the presence of noise. Speech words correctly. The SRT decibel level of these thresholds is 25dB HL (nor- testing in noise can consist of different typically obtained approximates the mal range), yet the individual presents types of noise, such as a shower noise average of 500, 1000 and 2000 Hz with a mild degree of hearing loss at or the noise of multiple people talking tonal thresholds for individuals with 2000 Hz. It is also possible that an in the background. The noise can 16 Hearing Loss Magazine also be presented at different levels one purchases hearing aids, results turn, provides information regard- relative to the level of the speech stimu- from this test are used to set the hear- ing the condition of the middle ear lus being presented to the listener. The ing aids’ maximum loudness levels so (such as the possibility of middle ear scores that are obtained can provide that loud sounds are not amplified by fluid being present, perforation of the the audiologist with key information, the hearing aids to a degree that they eardrum, etc.). including how well the individual: are intolerable. (1) can hear in quiet at an everyday Ear Canal Volume (ECV): This re- conversational level or if an individual Outer/Middle Ear Tests fers essentially to the volume of the ear has a relatively significant hearing loss Otoscopy: This entails the use of an canal in front of the tympanic mem- at his or her most comfortable listening instrument consisting of a magnifying brane and is derived through the use level; and, (2) can hear in the presence lens and a light for examining the ex- of tympanometry. ECV varies in size, of background noise. ternal canal and tympanic membrane being approximately double in size for For many individuals with hear- (eardrum). This visualization allows adults as compared to young children. ing loss, the audiologist might admin- the audiologist to determine if ear Ear canal volume can be affected by a ister this test at both everyday conver- wax is blocking the ear canal or other number of conditions. For example, if sational level and MCL. This allows for foreign material is present, and, if so, there is a TM perforation, ECV will a comparison of performance at both its extent; and if there is a possibil- be very large since it will also include levels and provides an indication as ity of some form of outer/middle ear the middle ear space behind the TM. to whether hearing aids are likely to pathology. On the other hand, if there is much be beneficial (i.e., if the individual wax, then the ECV will likely be does significantly better at the louder, Tympanometry: The audiologist reduced in size. MCL level). places a device with a rubber tip into the person’s ear canal which creates a Acoustic Reflex Testing:This test Loudness Discomfort Level (LDL): gradual change in the ear’s air pres- might be done subsequent to tympa- The LDL is the loudest level one can sure. The results indicate how well the nometry with the rubber tip still in the tolerate various sounds without the tympanic membrane (eardrum) moves ear canal. When loud sounds are pre- sound being uncomfortably loud. If relative to normative values, and in continued on page 18 Like HearingLossAssociation on Facebook September/October 2014 17 Audiometric cont. from page 17 R (right) and L (left) at both 500 and single syllable words at his or her most 3,000 Hz.These represent the tonal comfortable listening level (MCL) sented a small muscle in the middle ear Loudness Discomfort Level (LDL) since everyday conversation level usually contracts. This muscle contrac- values at these frequencies. For this (50dB HL) would be too soft or tion is called the acoustic reflex (or the individual, the LDL values occur inaudible. In this case, the listener’s middle ear muscle reflex). The purpose at levels that an audiologist would reported MCL in both ears was 80dB is to provide the audiologist with valu- typically expect for this degree/type HL. Interestingly, this intensity level able information regarding the health of hearing loss. is similar to what a normal hearing in- of the middle and inner ears, as well as Overall, the range between dividual would experience if a person other structures like the auditory nerve thresholds and LDL, though somewhat yelled at a distance of six inches. and parts of the brainstem. reduced when compared to those with Upon obtaining an individual’s normal hearing (more so at 3000 Hz), MCLs, 25 or 50 single-syllable word Case Example is sufficient enough for a hearing aid’s lists are presented. In this case, the To help you integrate the informa- circuitry/accompanying algorithms to client was presented with 50 words tion that I have presented here, I amplify most speech sounds without to each ear, one ear at a time and was have crafted audiometric findings significant difficulty, at least in the able to obtain scores of 80 percent and for an imaginary case; the findings range extending from 250 to 4000 Hz. 84 percent in the right and left ears, are displayed in the graphic on page respectively.