======Sound Localization======


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**Materials: **{{$demo.materials_description}}\\
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**Safety: **{{$demo.safety_description}}\\
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**Alternative titles:** Sound from Left or Right?  
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====Summary====                   
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====Procedure====  
  - Build the apparatus in advance: attach a straight, hard plastic tube to a narrow wooden block with three eyelet screws (one centered), align a ruler with the center, and connect each stethoscope earpiece to the tube ends using short lengths of flexible tubing.  
  - Pair students and review how to wear the stethoscope earpieces comfortably and hygienically.  
  - Have Student A face away from the block and place the earpieces in their ears; Student B stands behind and uses a pencil/pen to tap the hard tube at random spots along the ruler.  
  - Instruct Student A to call out “left” or “right” after each tap; Student B records position and response on the worksheet.  
  - Continue with 15–20 trials, including several taps near the center mark.  
  - Switch roles and repeat the test so both students collect data.  
  - Ask students to analyze where judgments were correct vs. incorrect and identify any region near the center where direction was hard to tell.  
  - Discuss how interaural time differences (arrival-time lags) and interaural level differences (loudness) inform the brain about sound direction, and why ambiguity occurs when the source is centered.



====Links==== 
Sound Localisation Experiment (similar concept to demonstration)- Dr Rajesh Verma Psychology: 
{{youtube>QpR-mjowZd8?}}\\

📄 Sound from Left or Right? - ncwit.org: [[https://www.teachengineering.org/activities/view/umo_ourbodies_lesson02_activity4]]\\


====Variations====
  * Repeat trials with eyes closed vs. open (facing away) to confirm vision is not providing cues.  
  * Tap with different materials (eraser, fingernail, wooden dowel) to compare how frequency content affects localization.  
  * Move the earpieces slightly forward/backward (keeping them safe and comfortable) to see if fit changes judgments.  
  * Add background noise at a low level to explore how noise affects localization accuracy.  
  * Extend the tube length and mark more positions to test whether greater spacing improves left/right discrimination.



====Safety Precautions====
  * Clean and sanitize earpieces between users; provide disposable covers if available.  
  * Instruct students to insert earpieces gently and never force them; stop immediately if discomfort occurs.  
  * Tapping should be light—do not strike near faces or ears and avoid loud impacts that could cause discomfort.  
  * Teachers should handle hot glue and cutting of tubing during setup to prevent burns or cuts.  
  * Keep the work area clear so students facing away from the setup do not trip.




====Questions to Consider====
  * Why do two ears help us tell where a sound comes from? (The brain compares tiny differences in arrival time and loudness between ears—interaural time and level differences—to infer direction.)  
  * Why is it difficult to decide left vs. right when the tap is at the center? (Both ears receive nearly the same time and level information, creating ambiguity.)  
  * How would unilateral hearing loss affect this activity? (Localization would be much worse because comparisons between ears are reduced or impossible.)  
  * Which frequencies are easier to localize and why? (High frequencies are easier via level differences due to head shadowing; low frequencies rely more on time differences.)  
  * How is this principle used in engineering? (Microphone arrays and signal-processing systems mimic binaural cues to localize sound sources.)