Aural Rehab Quiz #2

Speech Intelligibility Index (SII)

Proportion of the long-term average speech signal (LTASS) that is audible; calculated automatically on an SPL-o-gram.

Speechmap/ SPL-o-gram

Graph that shows unaided and aided audibility of speech signals in a child's ear canal; used to verify if hearing aid output meets prescriptive targets.

Long-Term Average Speech Spectrum (LTASS)

Average level of speech energy over time in quiet; shown as the gray shaded area on a speechmap.

Hearing Aid Output

The sound pressure level produced by the hearing aid in the ear canal; different from hearing aid gain (output - input).

Fitting Formula

A prescription for hearing aid gain at each frequency; considers hearing loss type, age, and ear canal acoustics. DSL v5.0 Child is commonly used in North America, NAL-NL2 in Australia.

Verification Procedures

Objective and behavioral measures completed by audiologists to confirm devices (HA, CI, BC HA) are working as expected.

Hearing Aid Verification

Objective measure to determine if features work appropriately, ensure speech audibility, and support functional assessment.

Electroacoustic Verification Procedures

Evaluate audibility of different inputs based on the gain provided by the hearing aid.

Speech Awareness Threshold (SAT)

Softest level at which a child detects speech stimuli.

Speech Recognition Threshold (SRT)

Lowest level at which a child can repeat or identify words/pictures correctly.

Speech Recognition Testing Definition

Child repeats or identifies words/phonemes/sentences, tested unaided and aided, in quiet and noise.

Speech in Noise Testing

Child repeats target words or sentences while background noise is present.

Test Box Measures

Objective testing using an SPL-o-gram; shows whether hearing aid output meets prescriptive targets across frequencies.

RECD (Real-Ear to Coupler Difference)

Used with unaided SPL-o-grams to personalize hearing aid verification for children.

Uncomfortable Listening Levels (UCLs)

Maximum levels of sound that should not be exceeded by hearing aid output.

Cochlear Implant Verification

Uses pure tones (250-8000 Hz) and speech recognition testing when developmentally appropriate.

Bone Conduction Hearing Aid Verification

Uses pure tones (500-4000 Hz), speech perception testing when appropriate, and test box verification.

Gain

The difference between hearing aid output and input.

Clinical Relevance of Verification

Ensures clarity of speech signal, demonstrates benefit from amplification, and supports spoken language outcomes.

Green line in speechmap

Soft speech input (about 55 dB SPL).

Magenta/Pink line in speechmap

Average conversational speech level (about 65 dB SPL).

Turquoise line in speechmap

Maximum power output of the hearing aid with loud input (around 90 dB SPL).

Speech banana (LTASS) below threshold markers

Parts of speech are inaudible, which may impact speech perception and language outcomes.

Hearing aid output exceeds UCL markers

The device is producing uncomfortably loud or unsafe levels for the listener.

College-aged listeners' thresholds are used a reference for?

0dB. Because their hearing thresholds are considered average.

Low SII value (e.g., .26)

Only a small proportion of the speech signal is audible, meaning limited access to speech sounds.

Higher SII value (e.g., .70+)

Most of the speech signal is audible, supporting better speech perception.

SPL-o-gram usefulness for parents, SLPs, and TODHH

It visually demonstrates what portion of speech the child can hear, making results easier to interpret and guide therapy/teaching.

Aided thresholds (red circles) close to prescriptive targets

The hearing aid is providing appropriate audibility across frequencies.