How to perform the A§E Sound Localization Test?

Modified on Thu, 25 Apr at 3:48 PM

Audiqueen contains two localization tests: (1) Azimuth localization and (2) ILD localization.

The azimuth localization is a typical localization test with 5 or 7 loudspeakers. This test requires the SoundC hardware.
The ILD localization test only requires 2 loudspeakers. It assesses the localization acuity based on high-frequency interaural level differences and is mainly useful to evaluate cochlear implant recipients.

Azimuth Localization

The azimuth localization is based on stimuli presented through multiple loudspeakers of SoundC (currently 5 or 7 speakers). Several stimuli are available:

A 1/3 octave narrow-band noise with 4 kHz centre frequency
Speech-Shaped Noise
LPF noise: low pass filtered noise with cut-off frequency = 400 Hz (see also white paper)
HPF noise: high pass filtered noise with cut-off frequency = 3000 Hz (see also white paper)

A§E azimuth localisation results. The sound was presented from 7 loudspeakers
and the listener had to point to the speaker he/she perceived to be the source.

After selecting a stimulus, it is presented randomly through one of the seven speakers. Each stimulus has a duration of 3 seconds and is presented five times. Intensity roving within a range of ± 2.5 dB is applied randomly.

Supported apparatus for Localization tests are: Amplifier & Speakers and SoundC (currently 5 or 7 speakers).

Procedure

Select A§E Azimuth Localization in the ribbon and click on New Measurement
Select SoundC from the drop-down list
In the Training mode, click on one of the speakers to send the stimulus to that speaker.
In the Test mode, Audiqueen plays a stimulus and the listener should point to the speaker he/she feels the sound is coming from. Click on this speaker icon to enter the response.
After the last presentation, Audiqueen plots an XY graph showing the median responses as a function of the real sources.

It also calculates the RMS value as a measure of the error compared to the normal line.

The RMS is calculated as the root mean square for all speakers of (the median response – the normal response)

Where

R_S = the median response for Speaker S
N = the number of speakers
norm = the normal value for Speaker S

ILD localization

The A§E ILD localization test is based on a narrow-band noise centred at 4000 Hz which is presented through two loudspeakers with different intensities to create an interaural loudness difference. This is used to assess the localization capacity as an indication of the central integration of binaural input.

Procedure

See this page to set up your hardware correctly (very important!).

Select A§E ILD Localization in the ribbon and click on New Measurement
Select the machine from the drop-down list
Use the controls to select binaural as the test ear and the conduction and the presentation level
In the Training mode, you can click on one of the speakers to present sound coming from that direction.
In the Test mode, Audiqueen presents the stimulus with different ILDs (randomly), to simulate different sound sources and the patient should point to one of the (sham) speakers that he/she thinks is the real source.
After the last presentation, Audiqueen calculates 2 values: (1) the variance of the responses, as an indication of the reliability of the patient's responses; and (2) the RMS value as a measure of the error compared to the normal line.
The variance is calculated as the average of the absolute value of every (score - the corresponding median score)