## 2 Materials and Methods
### Data Analysis
#### 2.3.3 Semi-Automated RFF Estimation
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Feature Name** & **Abbr.** & **Signals** & **Definition** & **Hypothesized Trend** \\ \hline Autocorrelation & ACO & Raw and Filtered Microphone & ACO is a comparison of a segment of a voice signal to a delayed copy of itself as a function of the delay [40; 41; 42]. & V \(>\) UV \\ \hline Mean Cepstral Peak & CPP & Raw and Filtered Microphone & CCP reflects the distribution of energy at harmonically related frequencies [43] and is calculated as the magnitude of the peak with the highest amplitude in the cepstrum (i.e., Fourier transform of power spectrum). & V \(>\) UV \\ \hline Average Pitch Strength & APS & Pitch Strength Contour & Pitch strength is calculated using Auditory-SWIPE\({}^{\prime}\)[25] by correlating a voice signal with a sawtooth waveform constructed across a range of possible \(f_{o}\) values; the \(f_{o}\) value that elicits the greatest correlation is considered the \(f_{o}\) of the signal, and the degree of this correlation is the pitch strength. APS is then calculated as the average pitch strength of the window. & V \(>\) UV \\ \hline Average Voice\(f_{o}\) & A\(f_{o}\) & \(f_{o}\) Contour & A\(f_{o}\) was calculated in the current study using the Auditory-SWIPE\({}^{\prime}\) algorithm (described above in APS). & V \(>\) UV \\ \hline Cross-Correlation & XCO & Raw and Filtered Microphone & XCO is a comparison of a sequence signal with a different segment of the signal [44; 45; 42]. & V \(>\) UV \\ \hline Low-to-High Ratio of Spectral Energy & LHR & Raw and Filtered Microphone & LHR is calculated by comparing spectral energy above and below a specified frequency. Using a cut-off frequency of 4 kHz [43; 46], the LHR may distinguish harmonic energy of the /i/ from high-frequency aspiration and friction noise (>2-3 kHz) of the /f/. & V \(>\) UV \\ \hline Median Pitch Strength & MPS & Pitch Strength Contour & MPS was included as an alternative to APS. & V \(>\) UV \\ \hline Median Voice\(f_{o}\) & M\(f_{o}\) & \(f_{o}\) Contour & M\(f_{o}\) was included as an alternative to A\(f_{o}\). & V \(>\) UV \\ \hline Normalized & NXCO & Raw and Filtered Microphone & NXCO was included as an alternative to & V \(>\) UV \\ Cross-Correlation & NXCO & Raw and Filtered Microphone & XCO, in which the amplitude of the compared windows is normalized to remove differences in signal amplitude. & V \(>\) UV \\ \hline Normalized & & & \\ Peak-to-Peak & PTP & Raw and Filtered Microphone & PTP is the range of the amplitude of a windowed voice signal. & V \(>\) UV \\ Amplitude & & & \\ \hline Number of Zero & NZC & Raw and Filtered Microphone & NZC refers to the number of sign changes & V \(<\) UV \\ \hline \hline Short-Time Energy & STE & Raw and Filtered Microphone & STE is the energy of a short voice segment [41; 47; 48]. & V \(>\) UV \\ \hline Short-Time Log & SLE & Raw and Filtered Microphone & SLE was included as an alternative to STE, and is calculated as the logarithm of the energy of a short voice segment. & V \(>\) UV \\ \hline Short-Time & STM & Raw and Filtered Microphone & STM is the magnitude of a short voice segment [41; 47; 48]. & V \(>\) UV \\ \hline Signal-to-Noise & SNR & Raw and Filtered Microphone & SNR is an estimate of the power of a signal compared to that of a segment of noise. & V \(>\) UV \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Acoustic measures for classifying voiced and unvoiced speech segments, with abbreviations (Abbr), the signal used to calculate the feature, feature definition, and proposed hypotheses surrounding feature trends in voiced (V) vs. unvoiced (UV) segments. Rows that are shaded orange indicate that the acoustic feature was included in aRFF-AP algorithm. Feature Set Reduction  
The 31-feature set was first examined to remove features that did not sufficiently capture the transition between voiced and unvoiced segments. The sliding window process in step 6 of the aRFF-AP algorithm was simulated to estimate each feature over time, ranging from the midpoint of the voiceless consonant and into the vowel.