CSD 494 Chapter 2


a graphic representation of hearing thresholds as a function of stimulus frequency.


an instrument for measuring hearing sensitivity for a range of frequencies.


the level at which sound can be detected only 50% of the time.

air conduction

refers to when sound travels through the air into the external auditory canal and stimulation progress through the middle ear, inner ear, and to the brain.

insert earphone

is an earphone whose receiver is attacched to the tube that leads to an expansive cuff. It can be inserted into the external auditory canal.

bone conduction

refers to the transmission of sound through the bones in the body, particularly the skull. Measured through a vibrator placed on the mastoid.

air-bone gap

is the difference between air- and bone-conduction thresholds; a difference may indicate a conductive component in the hearing loss.

sound level

is the intensity of sound expressed in decibels.


is the number of regularly repeated events in a given unit of time; ususally measured in cycles per second and expressed in Hertz (Hz).

Pure-tone Average (PTA)

is often used to assign a label to indicate the degree of hearing loss.

PTAs: Normal? Mild? Moderate? Moderate to severe? Severe? Profound?

Normal: 25 dB HL or better in adults or 20 dB HL or better in childrenMild: 26 - 40 dB HL.Moderate: 41 - 55 dB HL.Moderate to Severe: 56 - 70 dB HL.Severe: 71 - 90 dB HL.Profound: poorer than 90 dB HL


The audiological examination usually includes speech testing in addition to the audiogram. Results will indicate how hearing loss affects a patient's ability to detect and recognize speech and the level of sound necessary for comfortable listening.

Speech reception threshold (SRT)

is the lowest presentation level for spondee words at which 50% can be identified correctly.


are two-syllable words spoken with equal stress on each syllable.

speech discrimination score

a term that is not used very often anymore, refers to the percentage of monosyllabic words presented and can be identified correctly.

most comfortable loudness (MCL)

is the level at which sound is most comfortable for a listener.

uncomfortable loudness level (UCL)

the level at which sound becomes increasingly uncomfortably loud for the listener.

dynamic range

is the difference in decibels between a person's threshold for just being able to detect speech and the person's threshold for uncomfortable listening.

loudspeaker azimuth

is the position of the loudspeaker relative to the listener, measured in angular degrees in the horizontal plane.


converts electrical energy into sound.

sound field testing

determines hearing sensitivity or speech recognition ability by presenting signals in a sound field through a loudspeaker.

Dead air space

are unventilated air spaces.


to determine need for amplificationto compare performance with listening aid and without it -- to gain patient's confidence.to compare different listening devices.to demonstrate diminished speech recognitionto demo the benefits of visual speech info.to obtain info about envirnment-related listening issuesto assess performance longitudinallyto determine need for auditory or speechreading trainingto determine placement within a training curriculumto evaluate the appropriateness of educational placementto determine if expected benefit has been achieved

communication mode

it the means used by the sender to share information with a receiver and may include speech, sign, writing, hand gestures, or any other system of shared symbols.


is the smallest class of speech sounds in a language.

nonsense syllables

are syllables of speech that have no meaning.

speech features

are categorical properties of phonemes; a phoneme can be described as a bundle of speech features.

information transmission analysis

is a statistical procedure that analyzes the transmission of "speech features". If "eepee" and "eetee" are confused then the patient gets credit for the "voicing", but not the "place".

multidimensional scaling

statistical approach where data points are represented in a geometric space: two phonemes that are similar will be placed near one-another.

cluster analysis

A statistical approach that attempts to organize data into groups or clusters: b,d and g would cluster together.