# A Biologically Inspired Sound Localisation System Using a Silicon Cochlea Pair
## 3 Experiment and Evaluation
### Results and Comparisons
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{**System**} & \multirow{2}{*}{**Mic**} & \multirow{2}{*}{**Cues**} & \multirow{2}{*}{**Stimulus**} & \multicolumn{2}{c}{**Accuracy**} & \multirow{2}{*}{**Approach**} \\ \cline{5-5}  & & & & **0-45\({}^{\circ}\)/45-90\({}^{\circ}\)** & & \\ \hline
[17] & 2 & ITD & Periodic clicks & N/A & Two silicon cochlear models and the Jeffress model on chip \\ \hline
[21] & 2 & ITD &
\begin{tabular}{c} Sine tones, white \\ noises, and vowels \\ \end{tabular} & N/A & Instantaneous cross correlation with two silicon cochlear models on chip \\ \hline
[23] & 2 & ITD & N/A & N/A &
\begin{tabular}{c} Propose FPGA implementation of the \\ cochlear model, LIF neuron model and \\ WTA network \\ \end{tabular} \\ \hline
[20] & 4 & \begin{tabular}{c} IPD, IED, IID, \\ Spectral cues \\ \end{tabular} & Impulse & \
\begin{tabular}{c} 5\({}^{\circ}\) RMS error \\ (azimuth and elevation) \\ \end{tabular} &
\begin{tabular}{c} Three-chip system; One for onset \\ detection, one for BPF bank and IED/IID \\ cue extraction, and one for \\ cross-correlation, IPD \\ \end{tabular} \\ \hline
[22] & 2 & ITD & (50–300 Hz) sounds & \(3^{\circ}/12^{\circ}\) RMS error & Two silicon cochleae, zero-crossing \\ \hline
[63] & 4 & ITD & \textless{}300 Hz & \(3^{\circ}/8^{\circ}\) RMS error & Digital delay line on chip \\ \hline
[26] & 2 & ITD & \
\begin{tabular}{c} FM Noise, \\ Alarm Bell \\ \end{tabular} &
\begin{tabular}{c} FM Noise \({}^{\star}\) RMS error \\ 9.27\({}^{\circ}\)/12.48\({}^{\circ}\) \\ Alarm Bell \({}^{\star}\) 42.7\({}^{\circ}\)/54.76\({}^{\circ}\) \\ \end{tabular} & Delay line and CONP on FPGA \\ \hline
[64] & 2 & IID & Pure tones & \
\begin{tabular}{c} 1.09\({}^{\circ}\)/0.70\({}^{\circ}\) \\ RMS error \\ \end{tabular} &
\begin{tabular}{c} Event-based cochleae, IID, \\ “head” movement \\ \end{tabular} \\ \hline
[27] & 2 & ITD & \
\begin{tabular}{c} Noise, \\ Sine tones \\ \end{tabular} &
\begin{tabular}{c} 2.7\({}^{\circ}\)/5.5\({}^{\circ}\) RMS error \\ \end{tabular} & Two silicon cochleae (AER-EAR) \\ \hline
**This work** & **2** & **ITD(IPD)** & \begin{tabular}{c} **Spoken digits in** \\ **office** \\ \end{tabular} & \
\begin{tabular}{c} **2.82\({}^{\circ}\)/4.26\({}^{\circ}\) RMS error** \\ **On 1.32\({}^{\circ}\)/2.93\({}^{\circ}\)** \\ **unsigned average error** \\ \end{tabular} &
\begin{tabular}{c} **CAR pair** \\ **CNN** \\ \end{tabular} \\ \hline
**Human**[62] & \begin{tabular}{c} **2** \\ **ears** \\ \end{tabular} & \begin{tabular}{c} **Binaural** \\ **processing** \\ \end{tabular} & \begin{tabular}{c} **Broadband sound** \\ **sources** \\ \end{tabular} & \
\begin{tabular}{c} **4.03\({}^{\circ}\)/7.03\({}^{\circ}\) azimuth ** ** \\ **unsigned average error** \\ \end{tabular} &
\begin{tabular}{c} **Brief (150 ms) sound presented in front** \\ **of 6 subjects in a free field** \\ \end{tabular} \\ \hline \hline \end{tabular}   
* The RMS error is converted from the recognition rates in Reference [26]. **The unsigned average error is converted from TABLE I in References [65,66] at 5\({}^{\circ}\) elevation. **