Types of Measures in Speech-Language Pathology

Study Notes

Nominal measures: categories that are not relative to each other, e.g. "male" vs. "female"
Ordinal scales: attributes or categories ranked relative to each other, e.g. "mild", "moderate", and "severe" ratings
Interval scales: equal increments, e.g. a value of 50 is greater than 40 to the same degree that 60 is greater than 50
Ratio scales: have a true zero value, e.g. age, height, and weight

Precision: includes calibration, accuracy, and reliability
Calibration: process of converting voltage output into a reference standard measurement
Reliability: consistency of measurement, e.g. 5% error
Bias: systematic error, e.g. if the measure usually differs from the reference in one direction

Signal transducers: devices that change one form of energy into another, e.g. microphones, strain gauges, and pressure sensors
Active transducers: do not require a power source, e.g. thermocouple
Passive transducers: require a power source, e.g. photocell

Amplification: increasing the strength of the signal
Filtering: selecting specific frequencies or removing noise
Digitization: converting analog signals into digital format
Anti-aliasing filtering: filtering before a signal sampler to restrict bandwidth

Electricity: movement of charged particles
Current: flow of charged particles, measured in amperes (amps)
Personal safety: avoiding electrical shock, e.g. putting one hand in your pocket

Electrical safety: avoiding electrical shock, using valid ground contact
Infection control: minimizing risk of spreading infection, e.g. handwashing, sterilizing

Preamplification: enhancing signal changes prior to recording
Differential amplification: amplifying difference between electrical field changes

Digitization: digital sampling of an analog voltage signal
Sampling rate: dependent on type of signal, e.g. slow movement signals, voice, speech

Acoustic recording and analysis
Aerodynamic measurement
Laryngeal imaging
Electroglottography (EGG)
Laryngeal electromyography (LEMG)### Acoustic Analysis of Voice
Fundamental Frequency (Fo): measures the period of an acoustic waveform using the peak-picking method.
Frequency Range (Fo Range): measures the highest and lowest pitch a patient can produce.

Vocal Intensity: the acoustic correlate of vocal loudness, referenced to sound pressure level (SPL) and measured on a logarithmic decibel (dB) scale.
Intensity Measures: can be derived from various instruments, including Sound Level Meters, Acoustic Analysis Programs, and Aerodynamic Measurement Devices.
Habitual Intensity and Intensity Range (max and min): useful clinically.

Voice Range Profile: a plot of vowel production at minimum and maximum intensity (dB range) across minimum and maximum frequency (Hz and musical note range).
Phonetogram: a tool that provides a thorough description of a patient's physiologic limits of frequency and intensity.
Physiologic Frequency Range of Phonation: a tool that provides a thorough description of a patient's physiologic limits of frequency and intensity.

Jitter: cycle-to-cycle variability in frequency (a.k.a. frequency perturbation, pitch perturbation), measured from sustained vowel productions or "extracted" vowels from connected speech.
Shimmer: cycle-to-cycle variability in amplitude (a.k.a. amplitude perturbation), measured from sustained vowel productions or "extracted" vowels from connected speech.
Calculation: requires a quasi-periodic signal for reliable/valid perturbation analysis (i.e., Type I signal).
Jitter Purpose: measures frequency stability in sustained vowels.
Jitter Procedure: can be measured when recording sustained vowel(s) for MPT.
Jitter Norms: adults have a certain range of jitter values.